Oilseed Fact Sheet: Processing Edible Oils

can be regionally grown and pro- constuents interact readily with cessed. Sunflower, canola, flax, oxygen in the air or other compo- safflower and other oilseed crops nents in the oil to oxidize and form have been successfully grown in the products associated with rancidi- the Northeast. ty. Other of these minor components are an-oxidants, working to keep In a typical edible oil processing components from reacng with air to plant oil is extracted from the form the compounds seed first using mechanical ex- associated with tracon (expeller press) fol- rancidity. The lowed by chemical extracon following table (hexane extracon). By using shows some of both methods less than 1% of the the minor com- oil is le in the meal that is pro- ponents and duced. The majority of this meal is their effect on sold for use in animal feed raons. oxidaon. An- oxidants resist oxi- Introducon Components of Edible Oil daon so help to preserve the quality of the oil; pro-oxidants promote oxi- Edible oils used in the Northeastern Many components are found in a daon so do not help to preserve the United States are primarily sourced typical vegetable oil (Figure 1). This oil. from the Midwestern US and Canada. figure shows what is in canola oil;

Oils used for salad dressing as well as other edible oils have varying per- An-oxidants: resist rancidity those used for cooking uses such as centages of the same constuents.  Tocopherols (vitamin E) deep fat frying and pan frying are all Components listed as minor com-  Carotenoids called edible oils. With an interest in prise less than 1% of canola oil, yet Pro-oxidants: aid rancidity locally and regionally produced these parts play a large part in deter-  Water foods, oils are another food type that mining the stability, therefore shelf life, of the oil. Many of these minor  Transion metals (iron, copper)  Polar lipids  Chlorophyll

In general it is difficult to find a pro- cess that will remove the pro- oxidants without also removing the naturally occurring an-oxidants. Looking at a label of commercially prepared oil oen shows that aer processing an an-oxidant has been added to the processed oil to replace compounds that were removed dur- ing processing.

Figure 1: Components of canola oil Oilseed Fact Sheet: Processing Edible Oils

Commercial Edible Oil Figure 2: Commercial Processing Edible Oilseed Processing The commercial edible oil processing system is usually different from that performed by small-scale edible oil producers. There are steps involved which the small-scale producer would not necessarily need or want to employ with their product. Figure 2 shows a simplified diagram of com- mercial oilseed processing.

Seed is planted and harvested as with any other crop. This is followed by the cleaning process, which re- moves unwanted materials such as soil and other seeds from the har- vest. In some cases, it is preferable to shell the seed, removing hulls for a beer 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 condioned by heang be- fore being pressed for oil. The two The meal is then taken for other us- Cold Pressed Oils products of this process are the raw es, such as a poron of the feed for Small-scale pressing using expeller pressed oil and the press cake, which cale. The oil and hexane mixture is presses results in more oil being le is the compressed dry material of the dislled, and the hexane removed in the meal than results from chemi- seed. and collected. cal processing. Typically, the oil in the meal from small-scale pressing is in The raw oil is filtered before moving The remaining oil and the oil from the range of 8—15%. Commercial on to the final steps. The press cake, the inial pressing process are processing leaves less than 1% oil in however, is flaked and broken down bleached using bleaching clay, and the meal. While extracng the most for addional oil extracon. The deodorized , leaving the oil in its final oil as possible from the seed is one flakes are ground up and mixed with state which is packaged and sold. goal, oen producing oil at a temper- hexane to produce a slurry, which is This enre process contains several ature less than 49 C (120 °F) is also heated. During heang, the hexane procedures which the small-scale an important objecve. Oil pressed evaporates, and is collected for fur- producer may not need or desire for at this temperature below 49 C (120 ° ther use. While being heated, the their final product F) is known as “cold-pressed” oil and meal releases the remaining oil, is desired for alleged increased nutri- which is mixed with a small amount onal properes. Cold-pressed oil is of hexane that did not evaporate. Oilseed Fact Sheet: Processing Edible Oils also important if the oil is to be used refining, bleaching and deodorizing. acid, 98% oil. The acid is composed of directly as engine fuel because an oil Each of these steps used in large a soluon of 30% acid with 70% wa- pressed at a lower temperature car- scale processing may be duplicated ter. This total mixture is kept at 80° C ries lower levels of phosphorous. on a smaller scale. Some are more for up to 15 minutes, then rapidly High levels of phosphorous in the oil difficult to implement on a small cooled, seled, and separated via can be harmful to a diesel engine and scale, and may not be jusfied de- centrifuge. Commercial operaons is one of the compounds with a maxi- pending on the market for the end may include addional processes in mum limit set in the standard for product. the refining stage. vegetable oil for use as engine fuel. Refining RBD Oils Refining of oils may include neutrali- Edible oils purchased in stores are zaon of fay acids, removal of known as “RBD” oils. These are oils phospholipids (a compound contain- that have been Refined, Bleached ing phosphorous), and filtering of the and Deodorized. Each of these steps oil. Other processes may also be car- is used to create a final oil that is ried out to create a more stable oil consistent in taste, color and stabil- for subsequent processing. On a ity. As a result, these oils are general- small scale, removing hydratable and ly tasteless, odorless, and colorless non-hydratable phospholipids is one regardless of the original oilseed type goal, while removing parculates or quality. While this is the intent of through filtraon is a second objec- the processing, a locally produced oil ve. Hydratable compounds are ones may not need to meet the same ex- that will dissolve in water. Non- pectaons as the mass-marketed hydratable compounds will not dis- oils. solve in water, and will oen sele out or be removed by filtraon. Small-scale pressed oils that have not There is a small amount of water in Figure 3: A bag of bleaching clay. been processed or are minimally pro- edible oils, so water is present to dis- cessed retain flavors and smells com- solve the hydratable compounds. mon to the original oilseed. For ex- Refer to the “Oilseed Fact Sheet: Fil- ample, sunflower oil that is minimal- traon” for more informaon on fil- Bleaching ly processed retains a characterisc tering edible oils. Oils have a characterisc color when sunflower flavor and will pass this on inially pressed. When present on a to the salad dressing or foods fried in A simple acid wash of the raw grocery store shelf, vegetable oils this oil. pressed oil will cause many of the from different seeds have the same hydratable compounds to sele out nearly colorless appearance. These For deep fat frying, RBD oils are de- of the water and become parcles oils have been bleached to remove signed to stand up longer to the long that can be seled, centrifuged or the minor constuents that cause the term high heats demanded in these filtered from the remaining oil. Citric color. Other components, some of applicaons. acid is oen chosen as the acid for them desirable, are also removed this operaon. In one process, the oil during bleaching. Processing of edible oils is oen bro- is heated to 80 °C (176 °F). The oil is ken into the three RBD categories: then mixed in a soluon of 2% citric Bleaching removes the oil compo- Oilseed Fact Sheet: Processing Edible Oils

steaming the oil, which vaporizes the unwanted components and separates them from the desired material. For the small-scale or local producer, this process may not be desired, for sever- al reasons. Deodorizing removes fla- vor and odors which are oen prized in oils, enhancing the flavor of the foods they are used to prepare. Also, this process requires addional equip- ment which can be costly to purchase and maintain.

Figure 4: Two different types of bleaching clay. Shown on the le is a sample that is mixed with the oil, heated, and put through a filter press. On the right is a sample that is used as a filter in itself, which the oil is passed through. In both cases, the unwanted components in the oil are bonded with the clay, removing them. nents that increase the rate of oxida- moved (Figure 5). Bleaching clay is a on. When oil is used at high temper- type of clay dug primarily in the south- atures, for example when pan frying ern United States. It may be either or deep-fat frying, oxidaon is acceler- natural clay or acvated with an acid ated and the oil may develop undesir- wash. Acvated clay will aract and able characteriscs such as off flavor hold more compounds than natural or dark color quickly. Bleaching allows clay. Natural clay is used for bleaching the oil to be used for a longer period of cerfied organic oils. of me before these undesirable char- acteriscs occur. Deodorizing When pressed, oils contain a variety To accomplish bleaching, the oil is of components. These include vita- mixed with the required amount of mins, fay acids, protein fragments, bleaching clay (Figures 3 and 4). This traces of pescides, and occasionally mixture is heated to a high tempera- heavy metals, as well as many other ture [90 °C (194 °F) to 110 °C (230 °F)] materials. The majority of these either in the absence of oxygen (air) and enhance or detract from the flavor mixed. The undesirable (and desira- and smell of the oil. ble) compounds in the oil aach The process of deodorizing removes themselves to the bleaching clay par- all of these components from the oil, cles. Filtering or centrifuging removes leaving it flavorless and odorless, es- Figure 5: Bleached canola oil (le) and the clay parcles and the compounds senally the same as other oils which un‐bleached canola oil (right) are very aached to the clay, resulng in an oil are deodorized. This process involves different in color due to the natural col‐ that has the colorant compounds re- orants removed during bleaching. Oilseed Fact Sheet: Processing Edible Oils

Summary Note: This is not an exhausve re- source list nor do any of the oilseed Edible oil contains a variety of compo- nents and features, which all play a project partners endorse any of the part in its refinement and qualies. products or companies on this list. It is When commercially processed, edible intended as a resource and starng oil is colorless, odorless, and flavor- point for those interested in small- less, with few of its original qualies. scale oilseed processing.

Penn State College of Agricultural Sciences research and The small-scale edible oil processing Fact sheet prepared by: extension programs are funded in part by Pennsylvania setup contains many of the same fea- counes, the Commonwealth of Pennsylvania, and the tures but may leave out steps used in Russell Schaufler, Farm Operaons, U.S. Department of Agriculture. commercial processing, such as Penn State College of Agricultural Sci- bleaching and deodorizing. This allows ences. Where trade names appear, no discriminaon is intend- the oil to retain its original flavor, ed, and no endorsement by Penn State Cooperave Extension is implied. odor, and coloring. These are oen Douglas Schaufler, Dept. of Agricultur- desired traits in locally grown or small- al and Biological Engineering, Penn scale oils, as they enhance the foods State College of Agricultural Sciences. This publicaon is available in alternave media on the oil is used to prepare. request.

Resources The Pennsylvania State University is commied to the This project is supported by the North- Vegetable oil processing equipment policy that all persons shall have equal access to pro- east Sustainable Agriculture Research grams, facilies, admission, and employment without Tinytech (www.nytechindia.com) regard to personal characteriscs not related to ability, and Educaon (SARE) program. SARE performance, or qualificaons as determined by Universi- Bleaching clays is a program of the Naonal Instute ty policy or by state or federal authories. It is the policy of the University to maintain an academic and work Oil-dry corporaon of Food and Agriculture, U.S. Depart- environment free of discriminaon, including harassment. hp://pure-flo.com/products.html ment of Agriculture The Pennsylvania State University prohibits discriminaon and harassment against any person because of age, ancestry, color, disability or handicap, genec infor- Introducon to Fats and Oils Technol‐ maon, naonal origin, race, religious creed, sex, sexual ogy: Second Edion. AOCS Press, orientaon, gender identy, or veteran status and retalia- 2000. on due to the reporng of discriminaon or harassment. Discriminaon, harassment, or retaliaon against faculty, staff, or students will not be tolerated at The Pennsylva- Arcle discussing degumming and nia State University. Direct all inquiries regarding the acid washes nondiscriminaon policy to the Affirmave Acon Direc- tor, The Pennsylvania State University, 328 Boucke Build- Acta Chimica Slavaca Vol. 1, No. 1, ing, University Park, PA 16802-5901; Tel 814-863-0471. 2008, 321-328

Northeast Oilseed Informaon © The Pennsylvania State University 2013 University of Vermont: www.uvm.edu/extension/cropsoil/ oilseeds