Small-scale Oilseed Processing Guide
Dr. Douglas Schaufler Russell Schaufler Research Associate Research Assistant
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This guide has been developed by Penn State University Coopera ve Extension in the Department of Agricultural and Biological Engineering. It is intended to present the most effec ve and broadly accepted prac ces for small‐scale oilseed processing in the Northeast. As of the publica on of this document, the prac ces discussed within are current and up to date. This guide is a joint produc‐ on between Penn State and the University of Vermont. This guide will be made available in PDF form through various websites.
i Small-scale Oilseed Processing Guide
Dr. Douglas Schaufler Research Associate
Russell Schaufler Research Assistant
ii Copyright ©2013 by Penn State University Penn State Extension provides prac cal educa on you can trust. We help people, businesses, and communi es solve problems, develop skills, and build a be er future.
The Pennsylvania State University is commi ed to the policy that all persons shall have equal access to pro‐ grams, facili es, admission, and employment without regard to personal characteris cs not related to ability, performance, or qualifica ons as determined by University policy or by state or federal authori es. It is the policy of the University to maintain an academic and work environment free of discrimina on, including har‐ assment. The Pennsylvania State University prohibits discrimina on and harassment against any person be‐ cause of age, ancestry, color, disability or handicap, gene c informa on, na onal origin, race, religious creed, sex, sexual orienta on, gender iden ty, or veteran status and retalia on due to the repor ng of discrimina‐ on or harassment. Discrimina on, harassment, or retalia on against faculty, staff, or students will not be tolerated at The Pennsylvania State University. Direct all inquiries regarding the nondiscrimina on policy to the Affirma ve Ac on Director, The Pennsylvania State University, 328 Boucke Building, University Park, PA 16802‐5901; Tel 814‐865‐4700/V, 814‐863‐0471/TTY.
Published November 27, 2013
Acknowledgements We would like to acknowledge the growers and oil processors in the Northeast who provided insight into their oilseed processing opera ons.
This guide was funded with generous help from:
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Oilseed Processing in the Northeast Oilseed crops present an opportunity for farmers in the Northeastern U.S. to diversify their opera ons and provide a crop typically grown in the Midwestern and Great Plains regions. Many of the crops are adaptable and have been grown in the Northeast; some for a number of years and others only recently. The University of Vermont publica on, “Oilseed Produc on in the Northeast; A Guide for Growers of Sunflower and Canola,” provides informa on on the ag‐ ronomic aspects of these oilseed crops. This publica on extends this informa on into processing and other considera‐ ons for expanding into a small‐scale oil extrac on industry.
Oilseed crops provide oils with many uses. Oil from many of the crops can be used directly as fuel in vehicles modified to use as straight vegetable oil, or indirectly as fuel when the oil is first transesterified into biodiesel. Some producers have set up systems where the vegetable oil is first used for culinary use, as in a deep fat fryer, then picked up and pro‐ cessed into biodiesel. In this way the oil is used for both food and fuel, sa sfying both sides of the food vs. fuel debate. As food systems seek ways of becoming regionalized, vegetable oil produc on may become a part of this way of think‐ ing and ac ng.
The majority of the experience leading to this publica on has been from the produc on of canola and sunflower oils, as these are oilseed crops and oils that are produced in quan ty for culinary use. While soybean oil is the predominant oil in the United States, those seeking an alterna ve crop are more likely to look at crops like canola or sunflowers. The University of Vermont and Vermont farmers have been growing and producing oils for a number of years. Penn State first started growing canola as a petroleum diesel fuel replacement and later became interested in the produc on of edible oils. Both universi es have collaborated with farmers and processors to learn what has worked for them in the produc on of edible oils, and this guide is a culmina on of those experiences.
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v Table of Contents
Introductory Materials 1.1 Overview of Small Scale Oilseed Processing 1 1.2 The Regional Picture 5
Oilseed Processing Guide 2.1 Processing Edible Oils 7 2.2 Cleaning and Storage 12 2.3 Oilseed Presses 17 2.4 Oil Filtra on 24 2.5 Processing Regula ons 31 2.6 Evalua on of Six Commercially Available Designs 35
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the seed to be used for processing is tube; the screw spins and pulls the 1.1 Overview of placed in the grain silo, where it is seed from the bo om of the silo Small Scale Oilseed stored. Grain silos are kept under upwards to be fed into the press. A specific condi ons for storage, such as belt conveyor also may be used to
Pressing certain humidity levels; these vary convey the seed. from seed to seed. Since the oilseed Introduc on At the top of the auger, the seeds are press, crucial to the opera on, can run Small‐scale oilseed processing released. As the seed leaves the 24 hours a day, 7 days a week, the involves many steps. Despite being auger, a magnet inside the discharge storage unit can be used to store seed simpler than the commercial collects ferrous metal debris from the for many days of oilseed processing. equivalent, there are a number of seed (Figure 1.1.1). Examples of this important steps that must be taken to Auger debris are screws that have fallen make the system effec ve. From the loose in the machinery, metal filings When the seed is needed for grain silo, where the seed is stored, to from the elevator itself, and other processing, it must be moved to the the finished product, this sec on metal shards which have escaped the expeller press for oil extrac on. The covers the process that the small‐ seed cleaning process. majority of the oilseed processing scale producer may employ when procedure uses gravity as the feeding From the auger, the seed falls into a processing oil from oilseed. system. However, at some point the cone that contain high and low Grain Silo seeds must be move upwards to the switches. These switches sense when press. One way this is done is by using the funnel is full or empty beyond a A er being harvested and cleaned, an auger. An auger is a screw inside a certain point, and turns the auger on
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forward, where it is crushed, extracted depends on the press squeezing the oil back into the barrel, se ngs. Expeller presses usually have where it drips from a series of small adjustable p diameters and a holes and is collected. The crushed variable speed drive. seed is compacted and extruded Pressed Oil Tank through the press head, where it is also collected. The oil which is pressed in the expeller press comes out in a steady drip or The extruded pulp, known as meal, small stream, and is collected for has a variety of uses. Meal is further processing. Depending on the commonly used as feed for livestock, opera on in ques on, the collec on as it is high in protein. It can also be container could be anything from a used as pellets in stoves, which burn jug, a 55‐gallon drum, to something the meal at high temperature for more complex, such as an oil tank hea ng both homes and other designed for oil storage. buildings. The meal can also be used as organic fer lizer. Figure 1.1.1: Ferrous metal debris The most effec ve system collects the oil in a sealed tank. In this case, the oil collected by the magnet located be- Due to its oil content, meal must be going from the press to the tank fore the press. used fairly soon a er it is collected should be covered to prevent outside and off when necessary to keep the because the oil in the meal will go contaminants from entering the oil. cone full. In this way, the seed feeding rancid over me. The expeller press into the press does not need to be does not remove all of the oil from The tank should be built from a monitored, as the switch will prevent the meal; the amount which is smooth material which will resist the feeding system from overflowing. A third “overflow” switch should be used as a safety switch in case the high level switch fails. Oilseed Press
From the funnel containing the high and low switches, the seed is fed into the hopper on the expeller press (Figure 1.1.2). The press is a crucial part of the system, as it extracts the oil from the seed. An expeller press is composed of several components. From the hopper, the seed is fed into the barrel, in which a screw slowly turns. The screw pulls the seed Figure 1.1.2: Small expeller press for extrac ng oil from seed.
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corrosion by the oil. Stainless steel suspended in a s rred tank. The foots used are screw‐type pumps, which and food‐grade plas cs are the most are then completely removed in the create the flow using a slowly turning common materials. Materials such as next process. Either way is effec ve screw. Centrifugal pumps are not copper and aluminum are not and o en a combina on of the two is effec ve, as the oil moving to the desirable. used. The oil that has been extracted at this The Pump point will contain small bits of debris In order to enter the final stages, the that escaped the press, called the oil must be moved from the oil foots. Foots are suspended in the oil, storage tank to the filter, which will and are o en removed. Different finish cleaning the oil. The diaphragm methods are used for removal of the pump is an effec ve pump design for foots. One method involves se ling this process (Figure 1.1.3). Diaphragm the oil in the tank, allowing the foots pumps work in the same way as the to fall to the bo om of the tank. human heart, moving the oil through Some processing systems use a a series of chambers through valves. second method of keeping the foots Other pumps which are commonly
Figure 1.1.4: An example of a car- tridge filter, one common type of filter used in oil filtra on. filter must be kept at a constant pressure with very low flow. Pumps are either electrically operated or powered with compressed air. Filter
The pump from the previous step delivers the oil from the oil storage tank into the filter, the next component in the process. There are a number of different types of filters such as the cartridge filter shown in Figure 1.1.4. A common design used in food and other processing industries is the filter press. Figure 1.1.3: A small diaphragm pump. A pump pushes the oil through a
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pressurized filter made of a cloth Once filtered, the clean oil is pumped packaged as the final product, or mesh. The filtering agent is usually into a clean oil tank. This tank is moved on for further processing. diatomaceous earth, a fine powder similar to the pressed oil tank, except Most small‐scale processors will consis ng of ground up diatoms. To it is now only a storage unit. It must bo le the oil at this point. place the agent into the filter, the be sealed, like the pressed oil tank, to Summary diatomaceous earth is mixed with preserve the oil inside. Even when clean oil and pumped through the cleaned, the oil contains oxidants The oilseed processing system is a filter press, deposi ng the agent on which will cause the oil to go rancid complex and carefully managed the meshes. The oil to be filtered is a er a period of me of exposure to procedure. From the storage of the pushed through, capturing any foots air. For this reason, it is best kept seed, to the extrac on of the oil and inside the filter press in the form of sealed from oxygen. further cleaning and storage, it is “press cake”. important to maintain and In some cases, an inert gas such as understand the system. The filter press must be cleaned out nitrogen is pumped into the tank, to when full, removing the cake. The blanket the oil and keep the oil fresh. clothes are not cleaned with every In other instances, holding a vacuum filtering, and last through many in the tank performs the same filterings. func on. Clean Oil Tank The oil at this point is ready to be
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the meal. Meal is the remains of the seed a er the oil is extracted. Meal is 1.2 The Regional The Seed extruded from the p of the expeller The star ng point of the regional press, and collected, to be used as Picture oilseed system is the fields. Farmers feed for ca le and other livestock. The may grow canola or other oilseed meal is high in protein and other Introduc on crops as an alterna ve crop, or as a nutrients, and makes an excellent addi on to the feed ra on. In a regional food system, oilseed cover crop. The harvested seed is growth and processing forms a cyclical stored in bins and moved on to the The extracted oil is collected and system. Features of the system are next step of the process, the oilseed contained, where it branches out into u lized in mul ple ways, as discussed press. two uses. here. This system is one example of A er the cleaning process the oilseed The Uses of Extracted Oil what can be done using oilseeds in a press presses the seed, crea ng two regional se ng. products. The first of these products is Oil extracted from the seed has two
An example of a tractor run off of a com- bina on of diesel and straight vegetable oil.
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1.2.1). The tractors that Comple ng the Cycle harvest the canola seed As with the oil originally collected for from the fields are fuel, the refined biodiesel is used in designed to use SVO as local equipment. This decreases the fuel. This creates a cycle amount of petroleum fuels needed in which the product from the outside, increasing feeds back into the sustainability within the region. system that created the product. Summary
The oil which is From the plan ng of the oilseed and extracted as food oil is harves ng, to the various uses of the Figure 1.2.1: An example of a tractor run off of a used in the fryers in the oil extracted from the seed, to the combina on of diesel fuel and straight vegetable prepara on of food. The final return of the oil to the origin of oil fuels. system does not stop at the system, a region’s oilseed process this point. The oil which has been op ons for use. Some of the oil is forms a cycle. Everything that goes used for frying and cooking is further refined and bo led for use as into the system is returned, from collected as waste vegetable oil, and edible oil, while a por on is prepared providing cooking oil to restaurants refined in a biodiesel reactor. This for use as engine fuel. A number of and meal to ca le and other livestock, converts the oil into biodiesel, a form machines can be run on straight to the refining of used oil into of biofuel which can be used in many vegetable oil (SVO), through the use biodiesel. diesel engines without modifica on. of modified diesel engines (Figure
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cons tuents interact readily with In general it is difficult to find a 2.1 Processing oxygen in the air or other components process that will Edible Oils in the oil to oxidize and form the remove the pro‐ products associated with rancidity. oxidants without Introduc on Other of these minor components are also removing an ‐oxidants, working to keep the naturally Edible oils used in the Northeastern components from reac ng with air to occurring an ‐ United States are primarily sourced form the compounds associated with oxidants. Looking from the Midwestern US and Canada. rancidity. The following list shows at a label of Oils used for salad dressing as well as some of the minor components and commercially prepared those used for cooking uses such as their effect on oxida on. An ‐ oil o en shows that a er processing deep fat frying and pan frying are all oxidants resist oxida on so help to an an ‐oxidant has been added to the called edible oils. With an interest in preserve the quality of the oil; pro‐ processed oil to replace compounds locally and regionally produced foods, oxidants promote oxida on so do not that were removed during processing. oils are another food type that can be help to preserve the oil. regionally grown and processed. Commercial Edible Oil Sunflower, canola, flax, safflower and An ‐oxidants: resist rancidity Processing other oilseed crops have been Tocopherols (vitamin E) successfully grown in the Northeast. The commercial edible oil processing Carotenoids system is usually different from that In a typical edible oil processing plant performed by small‐scale edible oil oil is extracted from the seed first Pro‐oxidants: aid rancidity producers. There are steps involved using mechanical extrac on (expeller Water which the small‐scale producer would press) followed by chemical extrac on Transi on metals (iron, copper) not necessarily need or want to (hexane extrac on). By using both employ with their product. Figure methods less than 1% of the oil is le Polar lipids 2.1.2 shows a simplified diagram of in the meal that is produced. The Chlorophyll commercial oilseed processing. majority of this meal is sold for use in animal feed ra ons. Components of Edible Oil Many components are found in a typical vegetable oil (Figure 2.1.1). This figure shows what is in canola oil; other edible oils have varying percentages of the same cons tuents. Components listed as minor comprise less than 1% of canola oil, yet these parts play a large part in determining the stability, therefore shelf life, of the oil. Many of these minor Figure 2.1.1: Components of canola oil.
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In this typical method, seed is planted Figure 2.1.2: Commercial and harvested as with any other crop. Edible Oilseed Processing This is followed by the cleaning process, which removes unwanted materials such as soil and other seeds from the harvest. In some cases, it is preferable to shell the seed, removing hulls for a be er quality final product.
At this point, if the seed is large, the seed is crushed or broken up into smaller pieces. These uniform pieces are then condi oned by hea ng before being pressed for oil. The two products of this process are the raw pressed oil and the press cake, which is the compressed dry material of the seed. The raw oil is filtered before moving on to the final steps. The press cake, however, is flaked and broken down for addi onal oil extrac on. The is packaged and sold. This en re also an important objec ve. Oil flakes are ground up and mixed with a process contains several procedures pressed at this temperature below 49 solvent, o en hexane, to produce a which the small‐scale producer may C (120 °F) is known as “cold‐pressed” slurry, which is heated. During not need or desire for their final oil and is desired for alleged hea ng, the hexane evaporates, and product. increased nutri onal proper es. Cold‐ is collected for further use. While pressed oil is also important if the oil Cold Pressed Oils being heated, the meal releases the is to be used directly as engine fuel remaining oil, which is mixed with a Small‐scale pressing using expeller because an oil pressed at a lower small amount of hexane that did not presses results in more oil being le temperature carries lower levels of evaporate. The meal is then taken for in the meal than results from phosphorous. High levels of other uses, such as a por on of the chemical processing. Typically, the oil phosphorous in the oil can be feed for ca le. The oil and hexane in the meal from small‐scale pressing harmful to a diesel engine and is one mixture is dis lled, and the hexane is in the range of 8—15%. Commercial of the compounds with a maximum removed and collected. processing leaves less than 1% oil in limit set in the standard for vegetable The remaining oil and the oil from the the meal. While extrac ng the most oil used as engine fuel. oil as possible from the seed is one ini al pressing process are bleached RBD Oils using bleaching clay, and deodorized , goal, o en producing oil at a Edible oils purchased in stores (Figure leaving the oil in its final state which temperature less than 49 C (120 °F) is
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2.1.3) are known as “RBD” oils. These processed retain flavors and smells are oils that have been Refined, common to the original oilseed. For Bleached and Deodorized. Each of example, sunflower oil that is these steps is used to create a final oil minimally processed retains a that is consistent in taste, color and characteris c sunflower flavor and stability. As a result, these oils are will pass this on to the salad dressing generally tasteless, odorless, and or foods fried in this oil. colorless regardless of the original For deep fat frying, RBD oils are oilseed type or quality. While this is designed to stand up longer to the long term high heat demanded in these applica ons. Processing of edible oils is o en broken into the three RBD categories: refining, bleaching and deodorizing. Each of these steps used in large Figure 2.1.4: A bag of bleaching clay. scale processing may be duplicated and will o en se le out or be on a smaller scale. Some are more removed by filtra on. There is a small difficult to implement on a small amount of water in edible oils, so scale, and may not be jus fied water is present to dissolve the depending on the market for the end hydratable compounds. Refer to product. Sec on 2.4 for more informa on on Refining filtering edible oils. A simple acid wash of the raw Refining of oils may include pressed oil will cause many of the neutraliza on of fa y acids, removal hydratable compounds to se le out of phospholipids (a compound of the water and become par cles containing phosphorous), and that can be se led, centrifuged or filtering of the oil. Other processes filtered from the remaining oil. Citric Figure 2.1.3: A bo le of RBD oil from may also be carried out to create a acid is o en chosen as the acid for a local grocery store. more stable oil for subsequent this opera on. In one process, the oil processing. On a small scale, is heated to 80 °C (176 °F). The oil is the intent of the processing, a locally removing hydratable and non‐ then mixed in a solu on of 2% citric produced oil may not need to meet hydratable phospholipids is one goal, acid, 98% oil. The acid is composed of the same expecta ons as the mass‐ while removing par culates through a solu on of 30% acid with 70% marketed oils. filtra on is a second objec ve. water. This total mixture is kept at Hydratable compounds are ones that Small‐scale pressed oils that have not 80° C (176 °F) for up to 15 minutes, will dissolve in water. Non‐hydratable been processed or are minimally then rapidly cooled, se led, and compounds will not dissolve in water,
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States. It may be either natural clay or ac vated with an acid wash. Ac vated clay will a ract and hold more compounds than natural clay. Natural clay is used for bleaching of cer fied organic oils. Deodorizing
When pressed, oils contain a variety of components. These include vitamins, fa y acids, protein fragments, traces of pes cides, and Figure 2.1.5: Two different types of bleaching clay. Shown on the le is a sample occasionally heavy metals, as well as that is mixed with the oil, heated, and put through a filter press. On the right is a many other materials. The majority of coarser sample that is used as a filter itself, which the oil is passed through. In both cases, the unwanted components in the oil are bonded with the clay, removing them. separated via centrifuge. Commercial undesirable characteris cs such as off opera ons may include addi onal flavor or dark color quickly. Bleaching processes in the refining stage. allows the oil to be used for a longer period of me before these Bleaching undesirable characteris cs occur. Oils have a characteris c color when To accomplish bleaching, the oil is ini ally pressed. When present on a mixed with the required amount of grocery store shelf, vegetable oils bleaching clay (Figures 2.1.4 and from different seeds have the same 2.1.5). This mixture is heated to a high nearly colorless appearance. These temperature [90 °C (194 °F) to 110 °C oils have been bleached to remove (230 °F)] in the absence of oxygen the minor cons tuents that cause the (air) and mixed. The undesirable (and color. Other components, some of desirable) compounds in the oil a ach them desirable, are also removed themselves to the bleaching clay during bleaching. par cles. Filtering or centrifuging Bleaching removes the oil removes the clay par cles and the components that increase the rate of compounds a ached to the clay, oxida on. When oil is used at high resul ng in an oil that has the temperatures, for example when pan colorant compounds removed (Figure Figure 2.1.6: Bleached canola oil (le ) frying or deep‐fat frying, oxida on is 2.1.6). Bleaching clay is a type of clay and unbleached canola oil (right) are very accelerated and the oil may develop dug primarily in the southern United different in color due to the natural color- ants removed during bleaching.
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these either enhance or detract from Edible oil contains a variety of Bleaching clays the flavor and smell of the oil. components and features, which all Oil‐dry corpora on play a part in its refinement and The process of deodorizing removes quali es. When commercially h p://pure‐flo.com/products.html all of these components from the oil, processed, edible oil is colorless, leaving it flavorless and odorless, Introduc on to Fats and Oils odorless, and flavorless, with few of essen ally the same as other oils Technology: Second Edi on. AOCS its original quali es. which are deodorized. This process Press, 2000. involves steaming the oil, which The small‐scale edible oil processing Ar cle discussing degumming and vaporizes the unwanted components setup contains many of the same acid washes and separates them from the desired features but may leave out steps used Acta Chimica Slavaca Vol. 1, No. 1, material. For the small‐scale or local in commercial processing, such as 2008, 321‐328 producer, this process may not be bleaching and deodorizing. This allows desired. Deodorizing removes flavor the oil to retain its original flavor, Northeast Oilseed Informa on and odors which are o en prized in odor, and coloring. These are o en University of Vermont: oils, enhancing the flavor of the foods desired traits in locally grown or small www.uvm.edu/extension/cropsoil/ they are used to prepare. Also, this ‐scale oils, as they enhance the foods oilseeds process requires addi onal equipment the oil is used to prepare. which can be costly to purchase, Resources maintain, and operate. Note: This is not an exhaus ve Vegetable oil processing equipment Summary resource list nor do any of the oilseed Tinytech (www. nytechindia.com) project partners endorse any of the
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the quality of the seed and preserve 2.2 Cleaning and that quality through to the finished Storage oil. Reasons for storing oilseeds Introduc on Oil stored as seed does not turn An oilseed press may be the heart of rancid, so seed is not pressed un‐ an oilseed pressing opera on, but the l oil is needed quality and cleanliness of the seed available for pressing plays a large Oilseed presses are rela vely slow part in the ability of the press to per‐ compared to harvest speed; seeds form its job. This sec on focuses on need to be stored un l pressed the storage and cleaning of oilseeds Different crops come in at differ‐ that will be pressed for edible oil or ent harvest mes; one crop may Figure 2.2.2: Typical seed cleaner fuel. Oilseeds include seeds like cano‐ need to be stored while a previ‐ la, sunflower, soybeans, pennycress ous crop is pressed trash contained in the stored pile may or other seeds that contain a large be a star ng point for molds and enough quan ty of oil to warrant the Reasons for cleaning oilseeds hea ng. Usually me does not permit oil extrac on. Weed seeds present at harvest cleaning all of the seeds before stor‐ age, as harves ng and drying equip‐ Oilseeds are stored (Figure 2.2.1) for a may interfere with the extrac on ment commonly can process more period of me before finding their of oil in the press volume than cleaning equipment. The way to the oilseed press. To assure Weed seeds may add unwanted seed harves ng opera on plays a quality oil from the press the seeds taste or chemicals to the pressed large part in the cleaning effort need‐ going into the press need to be free oil ed following harvest. Taking the me from foreign objects, weed seed, Dirty seed will wear press & han‐ to be certain the combine is har‐ molds, and other contaminants. dling components more quickly ves ng the cleanest seed possible is Cleaning and storing the oilseeds cor‐ than clean seed me well spent. rectly following harvest will preserve Stones or other objects picked up Seed cleaning is o en combined with at harvest or during handling will filling bins directly before pressing. As damage pressing equipment seed is moved from the storage bin to the pressing bin a step in between Oilseed Cleaning can include cleaning. Oilseeds should be cleaned either be‐ Seed cleaners can be purchased new fore or following storage and before or used. Seed cleaners have not reaching the press. If a large quan ty changed drama cally over the years, of foreign material (weed seeds, seed and the cleaners of the 1930’s look pods, chaff) is present, seeds should Figure 2.2.1: Oilseed stored for im- remarkably similar to cleaners built be cleaned before storage as the mediate processing. today. Typical seed cleaners are
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allocated to enclose belt and chain drives, moving components, and oth‐ er hazards before using the equip‐ ment. Rewiring of an older cleaner will probably be required.
A USDA publica on, “Mechanical Seed Cleaning and Handling” de‐ scribes seed cleaning equipment and recommended seed screen sizes. Alt‐ hough an older publica on (1968), many useful tables and descrip ons can be found in this manual. Re‐ sources such as this are listed at the end of this sec on.
Figure 2.2.3: An older, but s ll func onal, version of a seed cleaner. When A seed cleaner will remove off size purchasing an older cleaner, resources should be expended to cover belt and density seeds and materials, but drives and other hazards. will not remove all dust and dirt from seeds. Another component called a dust remover will remove unwanted shown in Figures 2.2.2 and 2.2.3. are approximately the same size as dust from seeds. This is a component the desired seed. Seed cleaners use gravity separa on used by only a few oilseed press oper‐ (screens) and air separa on (fans) to A last cleaning step blows air through ators. Those who use it believe that separate seeds and unwanted materi‐ the sized seed and separates the light‐ the life of presses, augers and other al by size and density. Seed screens, er par cles, typically weed seed, from components will be extended because sized correctly, can eliminate seed the heavier, desired seed. Winnowing of the lower abrasiveness of the both larger and smaller than the de‐ such as this is commonly used to sep‐ cleaned seed passing through the sired seed. Running seed first over a arate the wheat from the chaff during press. screen sized correctly for the desired grain harvest. seed allows seed the correct size and Farmers have purchased both new smaller to fall through the screen, and used seed cleaners through deal‐ keeping gravel and larger seed out of ers or at private sales and auc ons. the desired mixture. Though the method of cleaning seed Flowing and shaking this mixture over has not changed enormously over the a screen sized slightly smaller than years, the enclosure of belt and chain the desired seed size screens out the drives and other components has smaller seeds, typically weed seeds. greatly increased the safety of newer Seeds remaining are the desired size, machines. If an older machine is pur‐ but may s ll contain weed seeds that chased me and money should be Figure 2.2.4: Typical grain bin
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Moisture Content of Stored How is Moisture Content This seed will need to be dried if it is Oilseeds Measured? to be stored and will not press well at this moisture content. Oilseeds that will be stored (Figure Moisture content may be measured 2.2.4) need to be kept at a moisture with the use of a handheld or bench Drying Seed content that does not encourage mounted moisture meter (Figure Most oilseeds harvested will need to hea ng within the seed pile or the 2.2.5), or calculated using the follow‐ be dried to some extent for both stor‐ growth of molds, bacteria or fungi. ing method. If available, the use of age and pressing. Even when mois‐ Growth of mold or bacteria may make the moisture meter is much quicker. ture content of the seed is acceptable the oil pressed from these seeds unfit When no moisture meter is available, for storage, most seeds do not press for human consump on. The oil may following these steps will provide an well in the oilseed press unless their s ll be tolerable for processing into accurate moisture content of the seed moisture content is about 7 – 9 %. biofuel, but the handling of moldy or stock. Table 2.2.6 shows ideal moisture con‐ dusty seed presents an airborne res‐ Weigh out an amount of seed and tents for pressing of various oilseeds. piratory hazard. If the seed is to be record the weight (call this weight Table 2.2.6: Ideal oilseed moisture con‐ sold, contaminated seed will have a W1) tent for pressing lower economic value than good seed. Place in an open container in an Moisture Content Crop oven at 100 C (212 F) for about 1 (%) hour, s rring occasionally Camelina 7‐9% Remove from oven and let cool Canola 7‐9% Weigh seed again (W2). Soybean 9‐11% The difference in the weight be‐ Sunflower 7‐9% tween W1 and W2 is the weight of the water that has been re‐ O en this drying is done before stor‐ moved. age so handling of the seed is mini‐ mized. When dried before storage, To find the moisture content in seed may be moved directly from the percent (%): storage bin, through a cleaning pro‐ Figure 2.2.5: Grain moisture tester. W1W2 cess, into the oilseed press. MC(%) 100 W1 As with grain, seeds may be dried A general rule of thumb recognizes Example: Weigh out 140 grams with ambient air or with heated air. 10% m.c. (moisture content) as being (5.0 oz.) of seed (W1). A er re‐ The choice is dependent on the quan‐ the high end for long term storage. moval from oven seed weighs 120 ty of seed to be dried and the equip‐ Storing seeds with lower than 10% grams (4.2 oz.)(W2). ment available. Ambient air is the more economical choice if the quan ‐ m.c. should produce good results. 140120 MC(%) 10014.3% ty to be dried is not too great and the 140 me is available to do the drying. If
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harves ng a large quan ty, hot air contac ng a distributor, so that you drying may be necessary because the know what ques ons to ask for the seed must be moved through the dry‐ crops you are interested in storing ing apparatus more quickly to make and drying. room for more of the harvest. There are many variables that affect Air drying consists of allowing the bin drying, such as depth of seed in grain to be in contact with outside air. the bin, diameter and motor size of For a small amount of seed, this can drying fan, diameter (size) of seeds, be accomplished by placing the seed ini al moisture content and desired in a thin layer outside on a dry day. moisture content. Bin floor perfora‐ Larger quan es require a blower on diameter can make a difference Figure 2.2.8: Mold in canola resul ng mechanism to force air through the in how a given bin will perform with from condensate formed as temperature lowered. seed. This can be done in either a different seeds. Oilseeds are o en grain bin or with grain aerators small in size, and will fall through the proper moisture content for storage, (Figure 2.2.7) screwed into the grain floor perfora ons of a typical grain they con nue to respire and respond stored in a large tote, small bin or bin. Canola, for example, will fall to temperature and moisture condi‐ small wagon. through a grain bin floor used for dry‐ ons in the storage container. As tem‐ ing corn, soybeans or wheat. Farmers Bin and dryer sizing, either forced am‐ peratures cool, condensa on may have used weed blocking cloth or bur‐ bient air or forced heated air, should form on bin or container surfaces or lap fastened over the floor so that be done in conjunc on with knowl‐ within the grain itself. These moist these larger diameter perforated edgeable grain bin distributors. Coop‐ areas are prime loca ons for molds to floors may s ll be used to dry the era ve extension service offices have start growth. For this reason, as out‐ smaller grains. Replacing the grain bin publica ons on these systems that side temperatures cool in the fall the floor with a floor specifically made for can provide informa on in advance of grain and container should be small seeds is another op on. checked each week for condensa on, Storage and when moisture is found the grain should be aerated to reduce the tem‐ Long term storage of oilseeds allows perature of the grain and remove the seeds to be harvested, stored and moisture so no more condensa on pressed for oil as the oil is needed. occurs. When the grain has cooled to Stored grains that are at proper mois‐ winter temperatures the periods be‐ ture content for storage need to be tween checks may be lengthened. monitored as temperatures and out‐ Problems with moisture occur when side moisture affect the storage condi‐ outside temperatures are dropping in ons and quality of the grain. Not pay‐ the fall and winter, not as tempera‐ ing a en on to storage can result in tures increase in the spring. Figure 2.2.7: Grain aerator showing seeds that are not fit for pressing into (le ) the aerator head and screw-in good quality oil (Figure 2.2.8). air tube and (right) the aerator head. A er seeds have been dried to the 15
Summary (Oilseed cleaner company) 2011. h p://www1.agric.gov.ab.ca/ $department/deptdocs.nsf/all/ Proper seed storage and cleaning of Mechanical Seed Cleaning and Han‐ crop1301 seed before pressing are two of the dling, Agriculture Handbook No. 354: steps affec ng the final product. Care Northeast Oilseed Informa on h p://naldc.nal.usda.gov/download/ throughout the en re process of CAT87208718/PDF University of Vermont: growing, harves ng, storing, and www.uvm.edu/extension/cropsoil/ pressing is necessary to ensure a oilseeds sa sfactory product. Selec ng Fans and Determining Air‐ flow for Crop Drying, Cooling, and Resources Storage. University of Minnesota. Note: This is not an exhaus ve re- Seed Cleaning 1999. source list nor do any of the oilseed h p://www.extension.umn.edu/ project partners endorse any of the A.T. Ferrell, Clipper Cleaners distribu on/cropsystems/dc5716.html products or companies on this list. It is 785 South Decker Drive intended as a resource and star ng Blu on, IN 46714 Storage of Canola, Alberta Agriculture point for those interested in small- phone: 800‐248‐8318 and Rural Development. Revised scale oilseed processing. h p://a errell.com/clipper
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2.3 Oilseed Presses Introduc on
An oilseed press (Figure 2.3.1) is the heart of an oilseed pressing opera on. This sec on focuses on small oilseed presses used for edible oil produc on or for producing oil for fuel or biodiesel produc on. Oilseed presses separate oilseeds such as sunflowers, canola, and soybeans into oil and Figure 2.3.2: Expeller Press (screw press) diagram. oilseed meal. Pumpkin or grape seeds and brazil nuts are examples of pan frying applica ons, or in deep fat press oil from a wide variety of seeds materials that are less known and can frying. Soybean oil (usually called and nuts. Some presses offer more be pressed for their oil in these “vegetable oil”), corn oil, sunflower flexibility than others, so examine machines. oil, canola oil, peanut oil, and carefully the claims of the press Oil from the press is raw oil, and is safflower oil are common examples of manufacturer before purchasing a used either as a food product or as an these edible oils. This large range of press for a par cular purpose. If industrial product. Food products oils points to the flexibility necessary possible, conversa ons with others include raw oil in dressings or alone, in an oilseed press if it is to be used to who have used a par cular press will be valuable. Vegetable oils typically found in the marketplace are RBD oils. This means that the oils have been Refined, Bleached and Deodorized a er the ini al removal from the oilseed. Sec on 2.1, Processing Edible Oils, describes these terms and the procedures that may be used for each process. For a small oil producer, some of these processes may be useful to incorporate into the oil processing line and others may be outside the scope of the opera on. Oilseed Presses
Available small oilseed presses are of two major types; screw or expeller Figure 2.3.1: Oilseed press. 17 presses (Figure 2.3.2) or reducing work best will be determined. Much through the press. The moisture in the screw/cage presses. Many presses are of this work is on a trial and error seed es up the oil and does not allow manufactured overseas while at least basis, and when proper se ngs are the oil and meal to separate as it one is now available from a United determined they should be recorded should. States manufacturer. Informa on so they are saved for reference and as All seeds have moisture contents at about many of the presses used in the a star ng point for the next harvest. which they press best. A general rule Northeastern United States is being Moisture Content of Seed to start from is that the ideal moisture collected and will be available as a for pressing is in the 7‐8% range. separate informa onal bulle n. For an oilseed press to operate Experience shows canola presses best properly, the incoming seed must be in the 6‐8% moisture content range, Oil Produc on clean and of the proper moisture with other oilseeds requiring similar content. Seed cleaning and storage Oilseed presses vary in size and the moisture contents. If the moisture informa on is provided in Sec on 2.2: amount of oil extracted varies content of the seed being pressed Cleaning and Storage. between seed types (Figure 2.3.3). As drops too low the temperature of the a result, the capacity of an oil seed Generally 10% is used as a rule of press head increases when pressing press is o en given in the weight of thumb for the moisture content at and will make it difficult to stay under seeds that can be processed per hour. which to store grain and seeds. While the 120F (50C) temperature limit for Depending on the material processed, the seed will store well at this cold pressed oil if that is important to the expected oil output will vary moisture content, it most likely will the opera on. Lower moisture greatly. For canola, about 1/3 of the not press well. Seed that is too moist content seeds result in higher press seed weight going into the press will will produce meal that is gummy and temperatures and a lower yield of oil. will not produce oil as it passes be produced in oil, while the Moisture content is o en the culprit if remaining 2/3 will be meal. Other seeds will give different oil and meal ra os.
Presses of these types are typically rated in the 3 kg (6.6 lb) to 100 kg (220 lb) of input material per hour range. Requirements for Effec ve Oilseed Pressing
Informa on provided in this sec on has been gathered from experience and discussions with numerous oil producers and providers of oilseed presses. As experience is gained with Figure 2.3.3: Examples of oilseeds including (from le to right) camelina, a par cular press the se ngs that soybeans, and canola.
18 pressing is difficult. On one occasion, manufacturer delivered the news that or taste desired in the finished oil. It is bags of canola at 7% moisture content the press barrel needed to be heated difficult to produce high quality edible to be pressed were placed on the to about 93° C (200° F) for pressing to oils when star ng with low quality floor of the pressing area. When work correctly with this high oil seed. pressing me came a week later, the content nut. Without this informa on Likewise, seed that contains mold seed would not press. A er numerous a great deal of me was used from too much moisture during failed a empts at ge ng the press unproduc vely as various lower harvest or storage (Figure 2.3.4) will started with this seed, the moisture temperatures, speeds and p sizes have a no ceable odor and may content was tested again and had were unsuccessfully tried. contain toxins that carry through into dropped to 4%. Unknowingly the seed Seed Quality the pressed oil. had been stored directly under a hea ng vent and had dried Seed quality is also important, as seed Pressing Temperature considerably by heated air blowing harvested either before or a er When reading the ingredients on across the bags. op mal ripeness can impart unwanted food, have you noted how vegetable flavor or chemical characteris cs to For informa on on moisture contents oils are listed? Some mes oil is listed the oil produced from that seed. for pressing, consult someone familiar as “expeller pressed” or “cold‐ When green (not fully ripened) seed is with press opera on. O en an email pressed”. Expeller pressed oil means pressed for oil, the smell it produces or phone call to the press that the oil is extracted from the seed when pressed is not the same as the manufacturer will help in ge ng by a press as described in this sec on. smell of ripe seed being pressed. Oil started on a new type of seed. When Cold pressed adds an addi onal produced from green seed will not an opportunity to press Brazil nuts requirement that the oil is extracted have the characteris cs such as smell was presented, an email to the at a temperature of less than 49° C (120° F). Many people believe that the oil produced at a lower temperature have be er health characteris cs. Addi onally, cold pressed oils have a lower phosphorous level which is required if using the oil as straight vegetable oil (SVO) fuel in an internal combus on engine. Press Se ngs
Manufacturers produce presses that have characteris cs that can be changed to accommodate different sizes, shapes or types of seeds or nuts. Not all manufacturers accommodate Figure 2.3.4: Properly stored seed (le ) as compared to moldy canola seed all of the following se ng changes, (right). but most allow at least some of the
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se ngs. Remember that the press should be shut off and the power disconnected before changing the se ngs. For screw type presses:
distance between end cap (press head) and screw end
speed of press
p size (diameter of hole through which meal is expelled)
type of screw (distance between and depth of auger flights)
Considering each of these characteris cs in more detail provides Figure 2.3.5: Example of a press head. the effects of each se ng. Because each se ng can have an impact on overall on the oil/meal mixture. Too adjustment is made it can usually be other se ngs it takes me, record much back pressure, though, and the le for the dura on of the pressing of keeping and pa ence to find the press will no longer allow the meal to that seed. It is not a se ng that needs acceptable se ng for each type of pass through, effec vely blocking the to be altered con nuously. meal flow and stopping the flow of seed, or even each batch within a type Turning the press head out to increase material through the press. Too large of seed. It is for this reason that clearance looks like an easy process, a distance and the meal will pass opera ng a press is more of an art and usually it is. If the machine has through easily, leaving a large amount than a science. Changes in moisture been run for a long period of me, or of oil in the meal. Finding the correct content or other characteris cs may the hea ng element has been used on se ng is a balance between the meal also require changes to press se ngs the barrel and head while pressing passing reliably through the press and for acceptable oil recovery. then turning the press head may be extrac ng the maximum amount of oil difficult. Turning the press head in can Distance Between Press Head while doing so. be a trying proposi on because meal and Screw End On one type of press, this se ng is is already packed into the space The clearance between the end of the changed by turning the pressing head between the end of the screw and the screw and the press head itself (Figure in or out. As the head is turned, the press head. Reducing this clearance 2.3.5) is one common adjustment, threading either increases or means squeezing this material ghter, though not an adjustment available decreases the clearance between the and that’s not always easy to do. on all presses. As this clearance is end of the screw and the press head. Removing the press head and clearing made smaller, the force needed to Even a small adjustment (1/16 of a the material may be the only way to push the seeds through the press turn) can change the press from being relieve this pressure enough to be increases, crea ng a greater pressure produc ve to being plugged. Once an able to turn the press head in.
20 diameter may be the only variable present to change the oil extrac on rate, as there may not be a way to change the press head to screw end clearance or the screw speed.
Tip diameters that have been used successfully are presented in Table 2.3.7.
Table 2.3.7: Tip Diameters
Feedstock Tip Diameter
Brazil nuts 5 mm Figure 2.3.6: Effect of speed on oil produc on. Camelina 7 mm Speed of Press speed increases, the temperature of Canola 5, 6, 7 mm the oil and meal moving through the Many presses have a variable speed machine also increases. Temperature Flax 7 mm drive. This may be an electronically and efficiency of oil extrac on need to variable speed drive, a variable pitch Sunflower be balanced against overall oil 5, 7 mm drive, or another type of drive that produc on to decide on a screw (Hulls off) allows the pressing screw(s) to be speed. Sunflower driven at varying speeds. 10 mm Tip Diameter (Hulls on) Turning the screw(s) faster will put more feedstock through the press Tips are available in varying diameters Remember that every batch of seed in a set amount of me and increase for each press. Many presses come and every machine are slightly the oil produc on rate (gallon or liters with a range of p diameters to allow different, so these diameters are a per hour). This sounds like a great pressing of different feedstocks. place to start but may not be the best idea, but there are downsides to Typically ps are available from ~ 5 sizes for your feedstock and running the machine faster (Figure mm to ~ 15 mm diameter. Press p condi ons. Experiment with different 2.3.6). As the screws turn faster, more diameter is one factor that greatly p diameters un l the oil extrac on material is moving through the press influences the amount of “back rate is acceptable. Also realize that as and this provides less me for the oil pressure” on the meal/oil moving new ps become worn in, they to migrate out and be separated from through the press. Too large a become smoother and produce less the meal. As a result, the slower the diameter p and the feedstock is not “back pressure” on the meal passing press is run the higher the extrac on held back adequately and flows freely through. rate for oil; the less oil is le in the from the press with li le oil Reducing screw/cage presses use a meal. If cold pressing of the oil is a extrac on. Too small a p and the p different technique for pressing the oil requirement, then a slower speed is plugs, effec vely ending that pressing than the expeller screw presses. o en necessary e becaus as screw session. On smaller presses, p Opera onal requirements are similar, 21
set the press head to screw end clearance if a change is needed. Different clearances can be noted by coun ng the number of threads showing or by measuring this distance.
Most oilseeds that will be pressed require that the press be ini ally heated to a temperature of ~120 F (60 C). Typically this is done with hea ng bands that cover each press head of the press and a controller. Some heat band controllers thermosta cally control the heat of the heat band, while other heat bands are simply on or off. Typically about 10 Figure 2.3.8: It is important to wait un l the press has stopped releasing minutes are needed to get the meal and oil before shu ng off the screws. A hea ng band is shown on the press head up to the preheat le barrel. temperature. This can be measured with a thermometer but adjustments are made by possible need for addi onal inserted into a hole in the press ghtening (reducing) the distances components to handle the range of head or more simply with an between the bars to increase the back products you are considering pressing. infrared thermometer aimed at pressure and increase oil extrac on. Star ng the Press the press head. Some presses do Type of Screw not require prehea ng. Bear in mind that every press will Manufacturers may provide screws have slightly different requirements Start the press and select the with different pitches (distance for star ng and stopping. Steps below desired drive speed. between high points of the screw) or are for one par cular type of press, Once the press head is at the depths to be er handle the variety of but should translate well to any press correct star ng temperature open seed shapes and types available. For with slight modifica on. the gate allowing seed to flow to example, one press manufacturer Be certain the gate allowing seed the press. Oil and meal produc on provides a screw that will handle to the press is shut. This allows is not immediate; it may take soybeans more readily than the screw the barrel and press head of the several seconds to over a minute that handles canola, camelina and press to be heated without seed to start having oil drip or flow other smaller seeds. Check with the present. from oil holes in the barrel. supplier of the press before purchase Different oilseeds contain Be certain the desired p to be certain you understand the different amounts of oil, so the oil diameter is in the press head and
22 that is produced may range from a restarted soon (within a week?) then Komet (www.ibg‐monforts.com) steady drip to a steady stream. leaving the press without removing Piteba (www.piteba.com) the barrel and cleaning is all right. The Tabypressen (www.oilpress.com) Shu ng Down the Press press will start up again with only the Tokul (www.tokultarim.com) Close the gate that allows steps outlined above. feedstock to flow to the press. Summary Vegetable oil processing equipment Wait un l the meal flow slows As the center point of the oilseed Tinytech (www. nytechindia.com) considerably or stops, and oil no conversion process, the press can be longer drips from the barrel Northeast Oilseed Informa on used to extract oil from a variety of (Figure 2.3.8). University of Vermont: seeds. The quality of the product is www.uvm.edu/extension/cropsoil/ Shut off the screws. determined by many factors, including oilseeds Turn off heaters if they have been the se ngs of the press, as well as used during pressing. moisture content and proper storage of the oilseed. Manufacturers suggest removing and cleaning the barrels and screws of the Resources Note: This is not an exhaus ve presses a er shu ng down the press. Press manufacturers (not an resource list nor do any of the oilseed Experience has shown that if the seed exhaus ve lis ng) project partners endorse any of the flow to the press is shut off and the products or companies on this list. It is press is run long enough to expel the Ag Oil Press (www.agoilpress.com) intended as a resource and star ng material in the press, this may not be Egon Keller (www.keller‐kek.de) point for those interested in small- necessary. If the press is to be Kern Kra (www.oelpresse.de) scale oilseed processing.
23 Filtering of oil can be done in different weeks; it all depends on what size 2.4 Oil Filtra on ways depending on the cleanliness of par cle is expected to be removed by Introduc on oil desired as the final product. Four se ling. Small par cles will remain in of the most common filtering suspension for a longer me than As oilseeds are pressed to separate methods are: larger par cles, so the longer the oil the oil and meal, par cles of the se les the smaller the par cles are Se ling crushed seed are also carried into the that are le in the oil. oil. While the pressing opera on can Bag filters 1 micron is equal to 1/1,000 be modified to reduce the amount of Cartridge filters of a millimeter. There are par cles in the oil, some cleaning of 25,400 microns in 1 inch. A the oil will be needed to remove these Filter press human hair measures about 11 microns thick, while red poten ally unwanted par cles. If used Se ling blood cells are 7 microns. for fuel, par cles are nuisances as they clog fuel filters and stop the flow The least expensive and simplest of fuel to the engine (Figure 2.4.1). As filtering is done by se ling the While filtering in this way is an edible oil, some operators believe par cles out of the oil. Se ling may be inexpensive and rela vely simple, it that par cles in the oil show that the done a er the oil is pressed as a does not do as complete a filtering job oil is “natural” or locally produced. separate step, or it may be on‐going as mechanical filtering. Farmers who Other edible oil producers believe that as oil is collected from the press. the product should match “store Some press operators con nually s r bought” vegetable oil and should not the oil coming from the press and do contain any par cles or sediment in not allow se ling to occur in the the container. collec on tank. When sediment is collected in the tank, at some point In oil language, the “foots” are the materials removed when cleaning the the tank must be emp ed so that the sediment can be removed. By gently oil. Oilseed meal and oil are separated agita ng the oil and keeping par cles during the pressing process, followed by separa on of oil and foots during in suspension, the tank does not accumulate this sediment and does filtra on. not require occasional cleaning. All of the sediment is removed during filtra on.
A er a period of se ling me when the oil is considered “clean” the oil is siphoned, drained, or pumped from Figure 2.4.2: 100 milliliters of canola the tank leaving the residue behind on oil collected at pressing me shows the bo om of the container (Figure about 7 milliliters of sediment a er Figure 2.4.1: Result of using SVO fuel 2.4.2 & 2.4.3). Different operators without reliable filtering: clogged 1 week of se ling at room se le oil from a few days to a few fuel filters. temperature.
24 ra ng for their filters. O en filter ra ngs are referred to as a “nominal” ra ng, meaning the filter will remove most, but not all, of the par cles over a par cular size. An “absolute” ra ng of a filter means that the filter will remove all of the par cles above a par cular size. One example is a manufacturer that rates filters as 80% efficient, meaning that a 15 micron ra ng captures at least 80% of the Figure 2.4.3: In this tank pressed oil flows slowly from le to right. The oil par cles larger than 15 microns while passes across two par ons, allowing par cles me to se le. Most of the up to 20% of those par cles will pass se ling occurs within the first par on. through the filter. Expect to pay more for a filter rated as absolute. use se ling as their only method of thickness (viscosity) of the oil Bag filter filtering and use the oil as fuel with no decreases, the par culates will drop further processing find that fuel filters more quickly to the bo om of the oil A bag filter (Figure 2.4.4 & 2.4.5) is on their equipment s ll clog earlier container. Se ling of par cles will just as it sounds, a bag of a certain than when fueling with diesel fuel. occur faster when the oil is warmed. This indicates that par cles remain in Filtering through a cartridge, bag or the se led oil and that addi onal filter press will occur more quickly filtering should be done to provide a when the oil is warmed. A clean engine fuel. As a guideline, precau onary note is, however, that engine fuel filters used in agricultural warming the oil also causes more equipment are nominally rated at rapid degrada on of the oil through 12—14 microns, so if a fuel filter is oxida on, a process that leads to oil plugging rela vely quickly it means rancidity. If the oil is warmed that par cles at least this large are s ll significantly it should be covered with suspended in the oil. an inert gas such as nitrogen to reduce the occurrence of oxida on. If the oil is used as a food product, the par culates remaining in the oil may How well does a filter work? be acceptable and add to the People are o en surprised to learn “natural” oil appeal. that a filter does not capture all of the Effect of temperature par cles larger than the ra ng of the filter as they pass through the filter. As with most processes involving oils, For example, many filter catalogs refer a warmer temperature will aid in Figure 2.4.4: Three bag filters and to a nominal ra ng or an efficiency se ling. As the oil is warmed and the housings arranged in series.
25 Bag filters are great for liquids like water which is very thin, but for thicker liquids like vegetable oil they may not be the best solu on. As the fi lter bag collects par cles from the oil, it becomes more difficult to push the oil through the filter. A pressure gauge is necessary to know when a maximum pressure has been reached, indica ng the need to change the filter bag. The used bag is discarded, and a new bag is installed. Figure 2.4.5: Bag filter without housing. People who use bag filters o en porosity material that passes fluid install a series of filters. The first filter through the bag and captures the may take out 25 micron and larger par cles inside of the bag. One of the par cles, the next filter will remove 10 simplest and not recommended forms micron par cles and the last filter removes 5 micron par cles. In this of the bag filter is a pair of old blue Figure 2.4.7: Cartridge filter with jeans with the legs ed off at the way par cle collec on is staggered clear housing used as final filter for bo om. and bags do not need to be changed fueling with straight vegetable oil. as o en. Bag filters are not Bag filters are usually used in (Figure 2.4.6) is a depth filter, conjunc on with a bag filter housing, meaning that the filtered fluid must a metal or plas c container that holds make its way through many layers of the filter. In this way the filter bag is filtering material. Along the way there given some rigidity in use. are many places for par cles to be A difference in pressure is needed to caught and held, thus cleaning the oil. move oil from inside the bag, through Like the bag filter, a cartridge filter fits the filter material, to the outside of inside a housing (Figure 2.4.7). The the bag and on to a clean oil Figure 2.4.6: End (le ) and full (right) view of wound cartridge filter. housing may be see through for container. In general, bag filters work monitoring the color of the cartridge; under rela vely low pressure. If the inexpensive, and with the discarding as the cartridge catches more pressure becomes too great on the of the bag each me it is used it will par cles it becomes darker giving an inside of the bag, par cles are forced be an expensive op on if a large idea of the life lee . Th only sure way through the bag as well as the oil amount of oil is to be cleaned. of knowing how close to the end of its being cleaned. This defeats the Cartridge filter life the cartridge is ge ng is to install purpose of filtering, so keeping the a pressure gauge to monitor the pressure within the limits suggested Where a bag filter has only one layer upstream pressure of the filter. As the by the manufacturer is a good idea. of filtering material, a cartridge filter 26 The clogging of fuel filters and oil needs to be saved each me oil is resul ng reduc on of fuel to the filtered so that it can be used in the engine was too common before some next filtering cycle. An auger type operators started using a filter press. paint mixer driven by an electric drill Following the adop on of the filter is useful for mixing the oil with the press for cleaning the oil no more fuel filtering media. This mixture must be filters were clogged, indica ng the pumped quickly into the cavi es of achievement of a higher level of the filter plates so that the media is Figure 2.4.8: Filter press; a series of filtering plates are pressed together cleanliness. deposited evenly on the faces of the by a manual screw or by hydraulic plates. If the mixture is pumped How to use a filter press pressure. slowly into the cavi es, then the filter catches more par cles, the The use of a filter press is a bit cavi es between the plates never fill pressure will rise as it becomes more mysterious at first. Once the workings to the top and media is not deposited difficult to push the oil through the of the filter press are understood, this evenly across the plate surface. For filter. Again, manufacturers will give filtra on method is the most reliable this reason, the pump on a filter press guidelines of how high the pressure is of the filtra on types. Filtra on down may seem larger than necessary. The allowed to get before changing out to 1 micron is possible on a regular pump is sized to fill the filter press the cartridge. basis. quickly, then reduces the amount of oil pumped when oil is actually being Cartridges are not serviceable and are To prepare the filter press for filtering, filtered. discarded a er use. If large amounts a mixture of clean vegetable oil and of oil are to be filtered, this will be an the filter media (a very fine material A filter press pump holds constant expensive filtra on method over me. that acts as the filter) is pumped pressure on the oil/sediment slurry quickly into the stack of plates that that is going through the filtering Filter press are pressed ghtly together. This A filter press (Figure 2.4.8) is a type of mixture of oil and media deposits the filter used in filtering liquids in food media onto the face of the cloth processing and other systems. Apple covered plates as the oil passes juice is one liquid that uses a filter through, crea ng a buildup about press for cleaning the final product. 1/16 of an inch thick on the filtering Because the rela vely inexpensive side of each plate. This media now filtering media is the only part covers the fabric and becomes the discarded a er use, it may be the filter; the plates and clothes are re‐ most inexpensive filtering system over used numerous mes while the media Figure 2.4.9: Block of foots collected the life me of the equipment. and captured par cles are discarded from between two filter press plates. when the filter is no longer passing oil A filter press is made up of a number The yellowish colored material is from the dirty side to the clean side filtering media coa ng of plates, each of which is covered (diatomaceous earth) ini ally placed (Figure 2.4.9). with a porous fabric. This cloth is on filter plate cloth while the dark covered with a thin layer of filtering To make the clean oil and filter media colored materials are the foots collected. media that becomes the actual filter. mixture, the correct quan ty of clean
27 slowly falls off as clean oil is pushed How much oil/media to use through the filter plate. When a low A rule of thumb exists to find the pressure is reached, a pressure switch amount of filter media to use. For a turns on the electric pump again and typical 1/16 inch buildup on the plates builds pressure back to the high point use ~0.15 pounds (68 grams) of DE per when the pump shuts off. This cycle square foot (0.09 sq. meter) of con nues as oil is pushed through the filtering cloth area. As an example, for media and filter plates. a press that has 12 plates with each Filtering media plate measuring 10 inches by 10 inches find the DE needed as follows. A common filtering media is diatomaceous earth (DE) (Figure 1. Each end plate has one filtering Figure 2.4.10: Air operated 2.4.12). This filtering material is used surface and all other plates have diaphragm pump on filter press. two filtering surfaces. In this example there is a single face process. As sediment builds on the plate on each end; the remaining filter plates and media, the pressure plates are double faced. This is a on the oil is raised in steps un l a total of 22 faces. maximum pressure is reached. As flow 2. Each face is 10”x10” for a total of slows at a par cular pressure, the pressure is stepped up and flow increases. Any method of holding pressure is acceptable. A common setup includes an air‐ operated diaphragm pump (Figure Figure 2.4.11: Electric screw pump for 2.4.10) that is able to quickly pump filter press. the ini al oil and media mixture into in swimming pool filters and various the plate cavi es, and then holds food processing applica ons like the pressure as oil is pushed through the cleaning of apple juice. In food media. A source of compressed air is processing terms it is considered needed if this type of pump is used. GRAS (Generally Regarded As Safe) for Another setup uses an electrically filtering. Some processors add other driven screw pump (Figure 2.4.11) agents to the DE to capture specific with a pressure switch and par cles that they want to remove accumulator. The pump runs and from the oil as it passes through the builds pressure in the accumulator to filter. a high point, then a pressure switch Figure 2.4.12: 50 pound bag of diatomaceous earth (DE). For this turns the pump off. Pressure in the vendor designa on FW-14 works accumulator and oil being filtered well for filtering vegetable oil.
28 100 square inches. 22 faces x 100 sq. inches/ face is a total of 2,200 sq. inches for the press. 3. There are 144 sq. inches per sq. foot. 2,200 sq. inches/144 sq. inches/sq. . = 15.3 sq. on this press. 4. 15.3 sq. . x 0.15 lb DE per sq. . = 2.3 lb of DE for this press. How much oil to use is determined by the volume of oil held by the press. O en this is provided by the press manufacturer in the specifica ons. Slightly more volume of clean oil should be mixed with the required Figure 2.4.13: A cloth from a filter press, with residue from filtering. The resi- amount of diatomaceous earth. This due contains both filtering media and foots. mixture of clean oil and DE is circulated quickly through the filter oil will pass through the filter. This is the maximum for filtering as press un l all of the DE is deposited called blinding the filter and will occur suggested by the manufacturer. in seconds if filtering vegetable oil on the press plates. At this point Some mes while filtering the filtering without the use of filter media. incoming oil is switched to the oil to media stops allowing oil through be cleaned. It is important to not let When cloths become blinded they before the cavity fills with foots. pressure drop to zero inside the filter may be washed gently with a pressure Adding and mixing in a small amount press when switching from one source washer. Vigorous pressure washing of DE to the bulk oil being filtered of oil to another. If pressure drops will result in enlarging the holes increases the length of me that inside the filter press it is possible for present in the cloths and will render filtering occurs. The addi onal DE the filtering media that has been the cloths unusable. Filter press cloths keeps pathways open through the deposited on the cloths to slough off taken good care of will last a number foots as they build on the filter cloths, and drop to the bo om of the filter of years. allowing more oil to be filtered before press cavity. cleaning. The amount of media to add Extending the filtering me Why use filter media is found by trial and error as it Adding filtering media to the bulk of depends on the amount and size of If used alone, cloths (Figure 2.4.13) the oil being processed before it the foots in the oil. used in the filter press will only act as passes through the filter press Summary a surface filter. As foots are deposited increases the amount of me that the directly on these cloths, the foots filter press operates before cleaning. Filtra on of the pressed oil is quickly fill the available filtering spots. Ideally, the cavity between press necessary if used as fuel, and Once these holes are filled, no more plates fills just as the pressure reaches desirable for improved appearance if
29 used as edible oil. Se ling is a good equipment (h p:// www.uvm.edu/extension/cropsoil/ first step in filtra on, but does not www.metchem.com/index.htm) oilseeds provide a cleanliness standard needed Wesco used processing equipment for fuel use. Filter presses have been (h p://www.wescoequip.com/ found to be the most reliable method usedfilterpress.html) of cleaning oils. Nebraska screw press (h p:// www.nebraskascrewpress.com/ Resources index.html) Note: This is not an exhaus ve Filter Press Sources resource list nor do any of the oilseed Ag Oil Press (www.agoilpress.com) Vegetable oil processing equipment project partners endorse any of the Egon Keller (www.keller‐kek.de) Tinytech (www. nytechindia.com) products or companies on this list. It is Kern Kra (www.oelpresse.de) intended as a resource and star ng Northeast Oilseed Informa on Komet (www.ibg‐monforts.com) point for those interested in small- Met‐Chem used processing University of Vermont: scale oilseed processing.
30 problems which may end in fines or which are easy to clean, and should be 2.5 Processing other legal consequences. kept clean and in good condi on. Any surfaces in contact with the product Regula ons This sec on details the different should be smooth as well, and aspects of cleanliness in the Introduc on resistant to decay from normal workplace when it comes to the processing and cleaning procedures. Are you considering producing edible processing of edible oils, such as: oils for public consump on as a small‐ To prevent accidents involving glass Workplace surfaces scale oilseed processor? The main objects, it is important to protect any focus of this sec on is to present the Personal cleanliness and all glass objects such as windows, regula ons and requirements in terms Permi ed construc on materials ligh ng, and bo les. Replace as many of safety and sanita on for small‐scale of these objects as possible with Produc on Area producers who would like to process Processing Room Legend edible oils from oilseed. Requirements (1) Door with screen to prevent pests
Reasons for Cleanliness When determining the best loca on (2) Sink for hand washing for the produc on area , size is an There are many reasons why the (3) Spill kit for dealing with spills important factor. The produc on area regula ons currently in place are should be big enough to have plenty (4) Disposable gloves and hairnets important. Since the oils produced are of space for the equipment and Fly paper away from processing for general consump on, they need to (5) materials. It should also be spacious equipment meet the expecta ons of food enough to allow for ease of cleaning (6) Cracks caulked and sealed produc on found in any food industry. resul ng in a sanitary opera on. Pipes smooth and made of washable Diseases and harmful materials, if not (7) Equipment and material placement material protected against, can contaminate should be unobstructed and allow for the product and endanger the health (8) Bo les labeled properly safe movement around the area. of customers. As well as giving an Counter made of appropriate (9) opera on a bad name in the industry, The floors, ceilings, and walls should materials be constructed of smooth surfaces this can also cause a variety of legal (10) Floor smooth and clean
The Processing Room
31 sha er‐proof materials. This would running warm water for that purpose. cleanliness protocol. include materials such as It is important that the restroom be Personnel involved in the polycarbonate, lexan, or tempered constantly stocked with disposable manufacturing of the product, or glass. hand towels, hand soap, and toilet supervising its produc on, need to be paper. Any restroom should contain a It is important that fixtures in the properly trained to perform their sign which details the proper hand produc on area also do not tasks safely and with food safety washing methods, and serves as a contaminate the product. This means prac ces in mind. Personnel involved reminder to wash hands a er every installing fixtures such as ligh ng, in contact with the raw or finished contact with unsanitary materials. ducts and pipes so that condensa on doesn’t drip onto the product at any Equipment and Handling stage of its produc on. On the same The equipment in the processing area note, ligh ng and ven la on should in contact with the product, such as be adequate, keeping the workplace processing, holding, transferring, and well lit with a good airflow. filling equipment should be designed Drainage and Sewage for their intended purpose, and should be of the proper quality and It is important that the water supply materials to prevent corrosion. and drainage systems are of sufficient Preferred materials include PVC quality to allow ease of cleaning and piping, polished stainless steel, and sanita on. It is required that the other food grade plas cs. Materials produc on area contain a hand‐ not recommended are copper, brass, washing sink (Figure 2.5.1) near the and galvanized metals. entrance, with water of between 100 and 120 degrees Fahrenheit. Floor All surfaces, including pipe interiors drains and sewage systems should and work surfaces in contact with the also be adequate for sanitary product should be smooth, to prevent Figure 2.5.1: An example of a hand opera on and proper cleaning of the buildup and promote cleaning. They washing sink with proper signs re- facility and equipment. Promo on of should also be free of dirt, and be minding workers to wash hands a er good personal cleanliness in the accessible to cleaning. Cleaning and contact with any contaminants. employees is also important. Floor sanita on should be done on a regular drains may also be a good idea in case basis. product must follow certain oil is spilled and begins to pool. Such regula ons regarding clothing. These Employee Regula ons drains should lead to appropriate are: drainage areas. When ensuring that the processing Personnel must remove jewelry area meets sanita on standards, it is Restrooms are an important feature before coming into contact with not just the facility that must meet which should be within a reasonable the product, as jewelry can fall standards. Anyone coming into distance of the produc on area. They into and contaminate it contact with the product or the raw should contain a sink used only for materials needs to maintain a level of Clothing must be appropriate to hand washing, and should have 32 ‐ups. Bags and containers must be closed when not in use, and kept away from exposure to heat, cold, light and moisture which might damage or decompose them. Chemical Containment and Regula ons
The facility used in processing of oilseeds into food products may require a number of chemicals to aid in produc on and sanita on. These include such materials as: Figure 2.5.2: This is an example of a dispenser for hair and beard nets, which Cleaning compounds allows ease of access and promotes cleanliness in the workplace. Lubricants maintain cleanliness and prevent contaminants. Pes cides contamina on Food, drink, and tobacco products Fuels Hair nets (Figure 2.5.2) must be must be prohibited from the Sani zing compounds worn on long hair and facial hair, processing area. No smoking is to be Other chemicals as needed to prevent it from falling into the allowed in the processing area, and product ea ng and drinking is to be done in These materials are considered toxic appropriate areas away from the when working with food, and should Torso hair must be appropriately product and raw materials. be stored separately from the covered– shirts must be bu oned processing area. Their storage area or closed all the way Raw Material Handling should be secure, and be labeled Lab coats are a preferable and The materials used in processing and properly. Chemicals inside this area sanitary outer wear to consider when packaging of the product, such as the should be properly labeled and stored working with the product, as they oilseed and the bo les the product safely, in their appropriate containers. provide coverage and prevent will be stored in, must be stored Any cleaning agents must be used as contamina on. properly prior to and a er use. They their labels describe; only sani zers Not only must personnel wear the must be stored above the ground, approved by the EPA are allowed for appropriate clothing, but they must away from pests, excess moisture, and use in the processing area, and must also maintain a level of personal contaminants. Contaminants include be used according to their labels. hygiene expected in a food processing microorganisms and chemicals, as Regula on Administra on environment. Personnel must well as dirt and other unwanted properly wash hands before each substances. Regula ons for food safety and processing are found under Title 21 of shi , a er using the restroom, and Raw materials must also be properly the Federal Code. A link to the code is any me they come into contact with labeled and separated, to prevent mix 33 found in the references sec on of this that the poten al small‐ me food oil Distribu on” (Look for sec on. These regula ons are in turn producer can set up a clean, safe, and agriculture.state.pa.us link) administered and supplemented by func onal workspace. US Drug and Food Administra on state legisla on, usually under the Resources Code of Federal Regula ons Title 21: state department of agriculture, or department of health. Penn State food science food h p://www.accessdata.fda.gov/ entrepreneur site: scripts/cdrh/cfdocs/cfcfr/ To apply for a license to process oil for CFRSearch.cfm?CFRPart=110 general consump on in Pennsylvania, h p://extension.psu.edu/food/ use the link to the Pennsylvania entrepreneurs/star ng‐a‐business Vermont Department of Health Department of Agriculture (PDA) Regula ons for Food Service Penn State University Creamery Good found in the references sec on. Establishments: Manufacturing Prac ces (to use as a Summary reference): h p://healthvermont.gov/ regs/03food_estab.pdf The safety of food produc on is h p://creamery.psu.edu/plant/dairy‐ important, not just for mee ng plant‐food‐safety‐plans/Creamery‐ regula ons, but for producing a GMPs.pdf/view Note: This is not a comprehensive list quality product which sells well and PA Department of Agriculture of resources on food processing brings customers back. When licensing page (for applying to get a regula ons. For more informa on, considering the facility in which the oil license): contact your regional sanitarian. In will be produced, many things ma er, Pennsylvania, this person is found Search Engine: “PA Wholesale Food such as equipment, space, sanita on, through the state Department of Processing, Manufacturing and and worker cleanliness. This sec on Agriculture. reviews these important factors, so
34 2.6 Small-Scale Oilseed Presses: An Evaluation of Six Commercially-Available Designs Chris Callahan1 and Hannah Harwood1 Heather Darby,1 Doug Schaufler,2 Ryan Elias2
1 University of Vermont Extension, Burlington, Vermont 2 Pennsylvania State University, State College, Pennsylvania As part of a project on adding value nents (Figure 1). In “cold-pressing,” to farm operations with food-grade the seed goes into a central hopper of oils, the University of Vermont Ex- the press and is moved through one tension and Pennsylvania State Ex- or more screws, crushed against a tension teamed up to evaluate the nozzle and screens to extract oil design and operation of several small without heating the seed above a -scale oilseed presses. While there is temperature of 120°F. Oil and meal a great deal of interest in the produc- are separated. tion of oilseeds, many questions arise Presses vary in the number and about post-harvesting processing, breadth of adjustment each needs and many of these concerns revolve and is capable of. Some presses have around the efficiency, affordability, multiple nozzles, with differing di- and best practices of an oilseed Figure 2. Nozzles vary on different ameter holes for differing crops press, which is the heart of the oilseed press designs. (Figure 2). Some have collars that oilseed production system. are heated to a given temperature structions and customer service can Most commercially-available oilseed before operation. vary greatly. Many of the presses are presses have the same basic compo- Unfortunately, manufacturers’ in- made overseas, and it can be difficult to get guidance in installing, wiring, and operating a press, either due to language barriers or geographical distance. In addition, the operational guidelines for different crops can vary. Here in the Northeast, where many growers are producing more than one type of oilseed crop, there is an interest in the type of press that can handle different crops, and in establishing some guidelines for commonly-used oilseed crops. This report aims to guide both estab- lished oilseed processors in best management practices and collabora- tive experiences and also aid new or prospective processors in decision- Figure 1. Standard components of a small-scale oilseed press. making processes.
35 Methods duct objective evaluations of six dif- RULES OF THUMB ferent press designs (Figure 3). The Researchers visited oilseed pro- team evaluated the AgOil M70, Kel- - Start with clean seed. cessing facilities across the Northeast ler KEK P0020, KernKraft 40, Komet - Test and take note of moisture to interview press operators and con- CA59G3, Oil Prince, and Täby 70 (this will vary by crop and press). presses (Table 1). - Take note of seed temperature. At each press location, the same seed - Make small adjustments as you was used to conduct a controlled ex- go, rather than big changes. periment. Sunflower seed (var: ‘Syngenta 3480’) was harvested in basic setup but was at a faster speed 2012 in Alburgh, VT; canola seed (adjusted Hz/RPM) to demonstrate a (var: ‘5535 CL’) was harvested in higher pressing capacity. Finally, 2012 in Brandon, VT; and soybeans each machine was run at a lower (var: ‘Boyd’) were harvested in 2012 speed (adjusted Hz/RPM) with the in Charlotte, VT. intent of yielding more oil. Quantita- Each press evaluation began with tive and anecdotal data from each normal operation, using the individu- method (and sometimes trials at ad- al operator’s preferred tuning of the ditional speeds) were noted. Each Figure 3. Researchers and farmers machine. The second method of op- method was repeated for each of the work together on press evaluations. eration for each press used the same three oilseed crops when possible.
Table 1. Specifications for six presses evaluated during the course of this study. (lbs seed/24 hrs) (lbsseed/24 capacity Estimated year + cost purchase Approximate source Power load Rated speed Adjustable head / barrel Heated available screws Multiple diameter nozzle Adjustable screw and head between gap Adjustable set of Ease
PRESS -
up
$8,500 1.5 kW / AgOil M70 700 240v X X X Simple (2012) 2.0 HP
$8,300 2.2 kW / Keller KEK P0020 1056 230v X X Simple (2010) 3.0 HP $15,000 3.0 kW / KernKraft 40 1200 220v X X X X X Finicky (2010) 4.0 HP $8,000 1.1 kW / Komet CA59G3 260 115v AC X X X Simple (2008) 1.5 HP Oil Prince $6,000 2.2 kW / 1800 220v X X X X X Finicky (KernKraft 20F) (2012) 3.0 HP $7,000 2.2 kW / Täby 70 1500 220-240v X X X X Moderate (2005) 3.0 HP
36 Press 1. AgOil M70 Roger Rainville of Borderview Re- MANUFACTURER search Farm in Alburgh, VT pur- CONTACT INFORMATION chased an AgOil in late 2012. The cold screw press is made in the [made in U.S.A.] United States, one of many deciding www.agoilpress.com factors for Rainville, who was inter- ested in readily-available parts and service. AgOil Mondovi, WI The AgOil has a simple design, with Figure 5. The AgOil M70 comes (877) 645-7737 a single screw and an in-line Varia- with three different sized nozzles: [email protected] ble Frequency Drive (VFD) mount- 220, 250, and 280. ed on the gear box (Figure 4). With relatively few adjustments to be seed flow into the press, observing others to achieve the maximum effi- made, the press is simple to get run- cleanliness and any potential mal- ciency for a given crop or condition ning according to Rainville, and can functions. A “blast gate” stops seed (Figure 5). be used to easily switch between flow when necessary. As used at crops without stopping to adjust. Borderview, after the band heater AgOil indicates that oil extraction has brought the temperature to ap- efficiency on the M70 is 82-90% of The press itself takes up very little proximately 120°F, the heater is re- the oil content in the seed. Trial re- space, with dimensions of approxi- moved and the machine’s motor is sults from this study show an aver- mately 10”x10”x39”. A clear feed turned on. A central screw inside the age of 24.2% net oil extraction hopper allows processors to watch barrel forces seed against the crush across three crops (canola yielded plate and retainer. Meal is extruded 24.6% oil, soybean averaged 5.7% in the form of oil, and sunflower averaged 38.6% crude pellets, oil). and oil drips from the crush Rainville has been satisfied with the barrel’s holes. AgOil so far, though it has a lower capacity than his other presses. A variable Press capacity averaged 697 lbs in speed controller 24 hours over multiple crops and allows opera- speed settings. tors to adjust the speed of the The press came with very minimal machine and setup instructions, so initial installa- allow for the tion was cumbersome according to extraction of Rainville. However, customer ser- more oil. There vice since then has been mostly reli- are three differ- able with this American-made oil ent nozzles that press. The company also provides come standard “crush tests,” in which a sample of with the press; the grower’s particular crop can be Figure 4. AgOil 70 press at 40 RPM, pressing soybeans. they can be shipped to the facility for testing. swapped out for
37 Press 2. Keller KEK P0020
The German-designed Keller KEK P0020, which is approximately 51”x12”x27”, is simple, with very few adjustments (Figure 6). Only the screw speed and the distance or gap between the head and the collar leave room for fine-tuning, making the press streamlined and effective.
Operator Lloyd Byers in Liverpool, PA, purchased the press for $8300 in 2010, with freight included and an installation cost of about $600. Byers reports that the Keller is easy to set up for pressing, and requires very little supervision once running. When the press is running for long periods of time, he checks a few times a day to make sure seed flow Figure 6. The Keller press has a single barrel and drive. and press operation are optimal, but can generally leave it unattended begin. Byers generally operates the the day of the press evaluation, nei- with a large quantity of seed to press at approximately 32 RPMs, ther soybeans nor canola could be press. and uses the number of visible pressed through the mill. Byers has threads between the screw end and pressed canola with great success in Unlike many other small-scale press- the nozzle as a reference for setting the past, but difficulties with soy- es, the Keller requires no “pre- the gap. Oil is extracted through the beans remain a problem. Customer heating” with band heaters to start. crush barrel, and the meal produced service, however, has been prompt Operators simply turn on the motor, is in a “flake” form (Figure 7). Byers and thorough. load the hopper with seed, and looks for flakes about the size and shape of potato chips to indicate that DISTRIBUTOR the press is operating as it should. CONTACT INFORMATION The consistency and speed of the meal is the most reliable indicator of problems with press operation. Man- [made in Germany] ufacturers promise that the use of “hard-wearing” steel reduces costly www.keller-kek.de maintenance and repair issues. Distributor in the U.S.: In this trial, the average mass oil Elwyn Beck fraction for sunflowers was 40.7%, Figure 7. This was the only press Sioux Falls, South Dakota and capacity averaged 130 lbs in 24 evaluated in this study that produces (605) 354-1323 hours. Byers has used the Keller meal in the form of flakes, rather mainly for sunflower seed, and on than pellets.
38 Press 3. KernKraft 40
The KernKraft 40 (KK40), owned and operated by Roger Rainville at Borderview Research Farm in Al- burgh, VT, is a workhorse design with high capacity and little supervi- sion required (Figure 8). Rainville’s model was purchased in 2010 and has been used to press over 60 tons of seed since then. A large hopper built into the press allows for smooth flow of seed into the two screw chambers. There is a slide closure between the hopper and screw to stop seed flow if necessary.
DISTRIBUTOR CONTACT INFORMATION
Figure 8. KernKraft 40 at Borderview Research Farm in Alburgh, VT. [made in Germany] in the other before operation. When Eric Hamilton at Circle Energy has Distributor in the U.S.: the screw becomes scuffed, polishing been integral in the setup, mainte- it will help draw more seed through nance, and operation of Rainville’s Circle Energy the barrel and increase overall flow KK40. Hamilton has been easily ac- Dodgeville, Wisconsin (Figure 9). cessible by phone or email and has helped troubleshoot and work Eric Hamilton, (608) 574-7449 The KK40 has twin barrels, which through problems with the press, increases the capacity of the press [email protected] even traveling to Vermont to help set overall. In 2013 trials, average ca- it up initially. pacity for varying crops and settings Many adjustments are possible with was 1033 lbs in 24 hours. Average the KK40: operators can modify oil mass fraction was 24.8% over- screw speed, nozzle/die size, the dis- all (23.8% for canola, 8.2% for tance between the screw end and the soybeans, and 38.0% for sunflow- nozzle, and the heat of the barrel ers). (with removable band heaters). There are also two available screw types In research trials and based small (hard/deep groove or soft/shallow batches, the dual barrels and mul- groove). The soft seed screw comes tiple possible adjustments some- with the purchase of the press; the times led to frustration. Often, one hard seed screw (useful for soybean, barrel would become clogged and flax, and other crops) must be pur- backed up while the other would Figure 9. Scuffed screws (left) need to be chased separately. A small “key” is continue extracting oil and meal polished (right) to increase press efficacy. removed from one screw and placed effectively.
39 Press 4. Komet CA59G3
This has been determined through experience with the press on differ- ent crops. Another indicator of smooth operation is the temperature of the oil being extracted; when it gets too hot, it may be because a blockage inside the crush barrel is creating friction. Once the press is running well, there is little fine- tuning or supervision required. After the seed has been run through com- pletely, the nozzle is removed from the press and cleaned thoroughly.
Though Penn State University never received installation and operation manuals from the manufacturer, Figure 10. The Komet CA59G3 is small but reliable. email response from customer ser- The Komet CA59G3 is made by the 5 mm nozzle for both sunflower vice has been prompt and thorough. IBG Monforts in Germany. It is an and canola. Because the press is a The Komet press is used at Penn electrically-driven model that is European model, all units are metric, State University for small batches of small in size (approximately including bolts and threads. Opera- seed, processing approximately 500 26”x22”x23”) and capacity (Figure tors can adjust the speed of the lbs of seed per year. “This has been 10). The Komet is a typical screw- drive. a real reliable, real consistent ma- type press, with a screw bringing chine,” asserts Schaufler. The press seed through the shaft to press oil During pressing, Schaufler looks for has actually been used to demon- out of it. a reasonable output when pressing to strate oilseed processing at farm be sure the mill is operating well. shows and outreach events, being The Komet is pre-heated to approxi- sent to various locations with little mately 130°F with a removable band DISTRIBUTOR more than a one-page instruction heater prior to pressing (for approxi- CONTACT INFORMATION manual on its operation. mately 10 minutes). Operators can adjust the screw speed; agricultural [made in Germany] The advertised capacity of the mill is engineer Doug Schaufler at Penn www.oekotec.ibg-monforts.de/ 3- 5 kg of seed per hour, which State University generally begins would equal up to 260 lbs of seed in pressing at approximately 55-60 Distributor in the U.S.: 24 hours. Though the Komet was RPMs. unable to be used for soybeans dur- Nebraska Screw Press ing these trials, the average oil mass While there is no adjustment in the Lyons, Nebraska fraction for canola was 34.4%, and gap between the tip of the nozzle sunflower seed averaged 45.1% oil. and the screw, there are multiple (402) 307-0280 The average capacity for these two nozzles, with varying diameters for crops, across speed setting, was 193 specific crops, though Schaufler uses [email protected] lbs in 24 hours.
40 Press 5. Oil Prince (KernKraft 20F) The Oil Prince, as it is sometimes of dripping oil indicates effective DISTRIBUTOR called, is another name for the Kern- operation. CONTACT INFORMATION Kraft 20F (Figure 11). This is a When the press slows down, Bou- smaller, single-screw KernKraft cher adjusts the sliding gate to mini- model with similar adjustability and mize seed flow until the machine [made in Germany] operation to the KK40 (page 5). works well again. Operators find that The Oil Prince has adjustable screw the press clogs less frequently when Distributor in the U.S.: speed, nozzle diameter, and two run at a lower speed. Clean seed go- available screw types (for hard seed ing into the hopper makes for more Circle Energy and soft seed). A sliding gate be- trouble-free pressing, and the built-in Dodgeville, Wisconsin tween the hopper and the screw al- magnet on the seed hopper prevents lows operators to control seed flow metal from entering the mill. Eric Hamilton, (608) 574-7449 at the throat of the press. Operators Average capacity of the press was [email protected] John Hutton and Meghan Boucher at calculated at 928 lbs per 24 hours. Coppal House Farm in Lee, NH heat Sunflower averaged 38.3% oil mass sometimes be a moving target. the collar with removable band heat- fraction during the trial, and canola ers and then add seed. For them, 2-3 This press, relatively new to its oper- averaged 26.6% across speed set- rows of holes in the crush barrel full ators, has a learning curve. During tings. On the day of the process of troubleshooting, the the press trial, oper- team also discovered a fracture in the ators could not press collar which may have been linked to soybeans effective- a prior issue with a ball bearing be- ly, despite an all- ing passed through the machine; this day attempt at data damage may have been preventing collection. The effective pressing of soybeans. problem could have While it runs extremely well and is been in the moisture reliable with canola and sunflower, level of the soy- other crops may take some adjust- beans; the Oil ment. Prince at Coppal House Farm has not yet been used to successfully press soy (Figure 12). Eric Hamilton at Circle Energy in WI, when called to troubleshoot this soybean problem, suggested adjust- ments and modifica- tions, but said that press operation can Figure 12. Close-up of collar head Figure 11. Oil Prince at Coppal House Farm in Lee, NH. and nozzle with too-hot soy meal.
41 Press 6. Täby 70 John Williamson runs State Line the plate, then back- Biofuels in North Bennington, VT ing off to leave a gap and relies mainly on a Täby model of approximately 2 70 oil press as the center of his oper- mm between the head ation (Figure 13). John has pressed and the screw. numerous crops (including sunflow- er, soybeans, canola, camelina, flax, In 2013 trials, the cranbe, safflower, mustard, and pen- average mass oil frac- nycress) with the Täby, which re- tion was 25.3% quires minimal adjustments and has (25.8% for canola, proven reliable over the last eight 7.5% for soy, and years. 38.3% for sunflower). The average capacity The Täby 70 was designed specifi- was 934 lbs per 24 cally for small-scale use, and to ex- hours. tract oil from a wide range of crops. A 2.2 kW motor drives the press, As with other press- Figure 13. Täby 70 oil press with custom-made oil pan. forcing seed through the crush barrel es, only clean seed at (or “press tube”) and nozzle. The the proper moisture should be Täby 70 is the language barrier. press has a thermostat and speed pressed, in order to extrude the max- Manufactured in Sweden, Täby control built into it (Figure 14), so imum amount of oil possible. The presses come with an instruction that the drive shaft rotates at variable Täby’s seed hopper has a built-in manual (installation instructions, speeds (maximum speed is 80 Hz or magnet to prevent any metal from safety warnings, and technical ad- 149 RPM). Operating instructions flowing into the press. A heater con- vice on troubleshooting and mainte- stress the importance of tightening trol on the gear housing stops the nance) in broken English and cus- the press collar all the way against press from running if the collar tem- tomer service can be delayed with peratures exceed 302°F. minimal domestic support.
Maintenance requirements are DISTRIBUTOR minimal with this machine. CONTACT INFORMATION Approximately every 10,000 operating hours, the gear oil should be changed. The spiral [made in Sweden] seed screw can become worn www.oilpress.com over time, and Täby suggests shipping the screw in for repair (re-hardening), rather than pur- Distributor in the U.S.: chasing a new one. Using only Magic Mill clean seed reduces and slows Upper Saddle River, NJ the wearing-out of multiple parts. (201) 785-8840 [email protected] Figure 14. Side-mounted control panel. One stumbling block with the
42 General Findings During the course of these evalua- pounds of seed in a 24-hour period Table 3. Capacity (lbs per 24 hr) based tions we assessed individual presses (Table 3). Not all crops were run at on press and crop, 2013 study data. and observed general trends in re- all screw speeds. Those selected gards to pressing capacity and net oil were based on operator insight and yield relative to speed, as well as whether or not seed could actually be quality characteristics of oil. pressed at the given speed.
As expected, the faster the press is Press Setup run, the more seed that is run through it. The press is, after all, a pump with It should be noted that these results the movement of material through it represent data from a single nozzle dictated by the speed of the screw and screw setup of each press for that pushes the material through. each specific crop (Table 2). However, the measured capacities vary notably by oilseed crop.
Table 2. Nozzle and screw type setup by press, 2013 evaluations.
N/A – The Keller press has only one option for press nozzle setup. Failed test – The evaluation team was unable to successfully press soybeans on these presses during this evaluation. Press Capacity Oil Mass Fraction or Yield A common consideration among A less intuitive finding of these eval- oilseed press purchasers is the capac- uations was the relationship between ity of the press, or how many tons it oil mass fraction and press speed. Oil can press in a day. In our evaluations mass fraction is the measured pro- we explored operation of the presses portion of oil in the test sample com- at different speeds (measured as ac- pared to the meal once the seed is tual screw RPM) and measured the pressed. It is often simplified or used amount of seed pressed in a given as an indicator of oil yield. amount of time. These data are sum- marized with capacity listed as
43 Table 4. Oil mass fraction (%) based Press evaluations revealed a maxi- on press and crop, 2013 study data. mum of oil mass fraction in most cases when the press was run more slowly than the default speed (Table 4; see boldface figures). The conclu- sion is that if an operator is interested in extracting as much oil as possible from a given seed, a slower press speed may be preferable. This is es- pecially true if the press is underuti- lized on an annual basis (i.e. over- sized for the current operation.)
Figure 15. Oil samples shipped to Penn Phosphorus Levels in Oil State University for quality testing. Phosphorus is used as an indicator of gum content in oils. Gums accelerate Fine-Tuning and Troubleshooting oxidation and therefore reduce shelf life due to rancidity. Gums can also A learning curve is to be expected, impede effective production of bio- especially when working with differ- diesel by disrupting the transesterifi- ent crops and conditions. With all cation process most often used to presses, there is a certain amount of make fuel from oil. In our press eval- troubleshooting and fine-tuning that uations we subsampled oil and tested each operator will undoubtedly go for equivalent phosphorus level us- through. ing AOCS Official Method 12-55 For example, when seed flow slows (Figure 15). down, as it will invariably do at times, identifying and resolving the Interestingly, phosphorus in oil is blockage is crucial to prevent caking minimized at lower speeds (Figure and overheating. Each operator in- 16). In some cases, it can be reduced volved in this project seemed to have by a factor of 3.7 by simply adjusting strategies for overcoming routine press speed. problems like this. One press manu-
Figure 16. Effect of pressing rate on phosphorus levels in oil by crop, 2013 data.
44 facturer suggests mounting a thermo- Table 5. General moisture recommendations and extraction rates by crop. stat and/or flow capacity controller to detect problems and automatically Ideal Pressing Average Extraction shut down the machine. Most agreed Moisture (%) Rate (%) that the press should be stopped, cleaned out, and started again in order Canola 6-9 25-30 to identify, and hopefully fix, the problem. Occasionally, turning up the Soybeans 8-12 8-12 speed of the motor can help clear a blockage. Sunflower 8-12 35-40
All operators mentioned the im- portance of taking time to learn the Additional resources: quirks (and strengths) of a particular press. Keeping detailed notes about Schaufler, D. 2013. Oilseed Fact Sheet: Oilseed Presses. Penn State Univ., the temperature, moisture, and cleanli- State College, PA. Available at http://www.uvm.edu/extension/cropsoil/ ness of seed going into the press, as wp-content/uploads/Oilseed-Presses.pdf well as press settings and calculated throughput, will help growers estab- Callahan, C., H. Harwood, L. Madden. 2014. Small-Scale Oilseed Presses. lish local operating procedures. It is University of Vermont Extension, Pennsylvania State Extension. our hope that this report gives pro- YouTube. http://youtu.be/4bfkb_FOn3w (accessed 27 Feb. 2014). spective oilseed processors an ad- vantage in getting started. A YouTube video complements this report and provides more information (see addi- For more information on oilseed production and processing, please visit tional resources at right). http://www.uvm.edu/extension/cropsoil/oilseeds
Acknowledgements
This research project was funded by Northeast SARE Grant 11-309 “Adding Value to Oilseed Crops by Producing Food Quality Oils.” UVM Extension and Penn State Extension would like to thank the following farmers for the willing participation in this project: Roger Rainville at Borderview Research Farm in Alburgh, VT; John Williamson at State Line Biofuels in North Bennington, VT; John Hutton and Meghan Boucher at Coppal House Farm in Lee, NH; and Lloyd Byers in Liverpool, PA. Without the time and shared experience of these press operators, this project would not have been possible.
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