University of Groningen Optimization of Jatropha Curcas Pure Plant Oil

University of Groningen

Optimization of Jatropha curcas pure plant oil production Subroto, Erna

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Chapter 1

Introduction

1.1 Need for bio-based energy source

Fossil fuels such as petro-diesel, LPG and kerosene are the main energy sources within the developing countries. However, fossil fuel is becoming more depleted and the price steadily increased over the last decade to values between 100 and 110 USD per barrel at this moment (Figure 1). Moreover, most developing countries are depending on fossil fuel imports and government’s subsidization of those fuels becomes a burden for government’s budgets. In addition, many negative environmental impacts are caused by the combustion of fossil fuel, i.e. the greenhouse effect associated with CO2 emissions. Therefore, utilization of alternative fuels is strongly recommended.

Figure 1 Price of NYMEX Light Sweet Crude Oil in the period 2003- 2013 [1]

An alternative fuel must be technically feasible, economically competitive, environmentally acceptable, and easily available [2]. Biofuels such as pure plant oil (PPO), biodiesel and ethanol have become promising alternative renewable and independent sources in developing countries. In general, biofuels can be used in the transportation sector, for electricity generation, and for domestic use such as cooking, lighting or heating.

Some countries have issued policies for the transition from fossil fuel to biofuel and introduced specific legislation. For example, the European Commission has issued a binding target of 20% for the share of renewables within the total energy consumption by 2020, and a minimum of 10% of the transport fuel must be based on biofuels in 2020 [3]. For the same year, China's Renewable Energy Law (RE Law) has set a binding target of 15% of all energy to come from renewable sources [4]. Likewise, Indonesia has issued a policy, The President

Regulation No. 5 Year 2006 on National Energy Policy, aiming for at least 5% of total energy consumption to be biofuel by 2025 [5]. For biodiesel in particular, Europe, Brazil, China, and India each have targets to replace between 5 and 20% of the total diesel consumption by biodiesel [6].

The term biofuel is defined as fuel produced from renewable biomass (organic materials that are plant or animal based, including dedicated energy crops, agricultural crops and trees, food, feed and fiber crop residues, aquatic plants, forestry and wood residues, agricultural wastes and other waste materials [7]. Pyrolysis oil, pure plant oil (PPO), biodiesel and bio-ethanol are well-known examples of experimental and proven biofuels.

Pyrolysis oil is a product of thermochemical decomposition of organic material at elevated temperatures in the absence of oxygen. Bio-ethanol is an alcohol made by fermentation, mostly from carbohydrates produced in sugar or starch crops such as corn, sugarcane, or sweet sorghum. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a gasoline additive to increase the octane level and reduce vehicle emissions.

In this chapter, the use of vegetable oil as fuel will be described in more detail. Vegetable oil has become the main feedstock for biodiesel production, especially as a petro-diesel substitute. Pure Plant Oil (PPO) is vegetable oil used directly as a fuel in suitable diesel engines without undergoing chemical change from its original characteristics [8]. Bio-diesel is defined as a fuel comprised of mono-alkyl esters of long-chain fatty acids (chain length

C14-C22) derived from renewable lipid - vegetable oil - sources [2]. It can be used in compression ignition engines with little or no modifications [9]. Biodiesel is produced by a trans-esterification reaction of lipid sources with short-chain alcohols, preferably methanol or ethanol.

1.1.1 Vegetable oils

Vegetable oil consists of mostly triacylglycerols (90-98%), but it also contains minor components such as free fatty acids (FFA) (generally 1–5%), mono- and diacylglycerols, phospholipids, chlorophylls, carotenes, sterols, tocopherols, phenolic compounds, metals, sulfur compounds and traces of water [10]. Triglyceride is a lipid consisting of three molecules of fatty acids covalently bonded to one molecule of glycerol (see Scheme 1). Commonly found fatty acids in vegetable oils are palmitic, stearic, oleic, linoleic and linolenic acid.

Scheme 1 Chemical structure of triglyceride

The main advantages of vegetable oils over petro-diesel are their ready availability, renewability, non-toxicity, and biodegradability. Meanwhile, the main disadvantages are the higher viscosity, lower volatility, and the reactivity of unsaturated hydrocarbon chains [2,11]. All vegetable oils are extremely viscous with viscosities ranging from 9 to 17 times greater than petro-diesel fuel [11,12]. Trans-esterification is the common method used to reduce the viscosity of vegetable oils such that this product, termed biodiesel, can be used directly in conventional diesel engines [12]. The use of vegetable oil-derived fuels led to substantial reductions in emissions of carbon monoxide (CO), poly-aromatic hydrocarbons (PAH), smoke, and particulate matter (PM) [13,14]. Furthermore, vegetable oil-derived fuels contribute to the reduction of greenhouse gas emissions in comparison to petro-diesel, since carbon dioxide (CO2) emitted during combustion is recycled in the photosynthesis process in the plants [2]. Reductions in net carbon dioxide emissions are estimated at 77– 104 g/MJ of diesel displaced by biodiesel [15]. In addition, vegetable derived fuels have an output-to-input energy ratio higher than petro-diesel. Typical results show that the life-cycle output-to-input (fossil) energy ratio of soybean oil, soy-biodiesel and petro-diesel is around 6.2, 3.2, and 0.83, respectively [16].

Vegetable oils have chemical structures different from petro-diesel. Classic diesel fuel consists of hydrocarbon molecules with chain lengths of C10-C15, while vegetable oils consist of triglycerides whose chain lengths range mostly from C16 to C22; either saturated or unsaturated. The average chemical formula for classic diesel fuel is C12H23, ranging from approximately C10H20 to C15H28. Triglyceride molecules have molecular weights between 800 and 900 and are thus nearly four times larger than typical diesel fuel molecules. The large size of vegetable oil molecules and the presence of oxygen in the molecules suggest that some fuel properties of vegetable oil should differ markedly from those of hydrocarbon fuels [11]. The chemical and physical properties of the fuel liquids are shown in Table 1.

Table 1 Fuel properties of common vegetable oil used as biodiesel feedstock

Type of oil CN LHV Density Kin.Visc. FP CP PP Ref. (MJ/kg) (kg/L) mm2/s °C °C °C Diesel fuel #2 45.8 45.2 0.847 2.39 78 -19 -23 [17] Edible oil Palm oil 49 40.14 0.9139 40.33 275 23 12 [18, 19] Rapeseed 37.6 39.709 0.9115 37.3 246 -3.9 31.7 [11, 20] Sunflower 37.1 39.575 0.9161 34.4 274 7.2 -15 [11, 20] Soybean 37.9 39.623 0.9138 33.1 254 -3.9 -12.2 [11, 20] Non-edible oil Jatropha 38 39.071 0.917 35.98 229 9 4 [21, 22] Kinematic viscosity were measured at 38 oC, CN - cetane number, LHV - lower heating value, FP-flash point, CP- cloud point, PP-pour point

Vegetable oil-derived fuels are usually produced from edible vegetable oils, such as soybean, rapeseed, sunflower and palm oils. They are not economically attractive since their prices are higher than diesel fuel, as can be seen in Figure 2. In addition, production of biofuels from edible vegetable oils is the main cause of increased global food market prices [23]. One of the most promising potential raw materials for biofuel production is from non- edible sources such as jatropha oil [23-27].

Figure 2 Price of diesel # 2 and edible vegetable oils (2003-2013) [1, 28]

Compared to other food-based crops such as palm, soybean and sunflower, jatropha is considered as a more sustainable feedstock for fuel production [23,26]. It is a non-edible oil, thus it will not impair any food security issue [29]. Jatropha oil provides a relatively high oil yield per area compared to other vegetable oils. It has a yield per hectare of more than twice that of sunflower and four times that of soybean (See Table 2). General description and the application of jatropha oil is described in more detail in part 1.1.2.

Table 2 Oil production per area of different oil plants [30]

Vegetable Latin name Liters oil/ha/yr Palm Elaeis guineensis 5,698 Coconut Cocos nucifera 2,578 Jatropha Jatropha curcas 1,812 Karanja Pongamia pinnata 1,250 Rapeseed Brassica napus 1,140 Peanut Ariachis hypogaea 1,018 Sunflower Helianthus annuus 915 Linseed Linum usitatissimum 458 Soybean Glycine max 430

1.1.2 Jatropha curcas L.: general description and application

Jatropha curcas, commonly known as physic nut (English) or purgeernoot (Dutch) or jarak pagar (Bahasa Indonesia) is a perennial oil-bearing shrub (normally up to 5 m height) belonging to the Euphorbiaceae family. The vegetable is a native to Central and South America, whereas it has been distributed to tropical and subtropical countries and mainly grown in Asia and Africa [31]. The tree has flexibility adaptation in the various environmental growing conditions. In general, jatropha is toxic to humans and animals. Phorbol esters, trypsin inhibitors, phytates, saponins and lectins (curcin) are known as the toxic compounds found in the seed of toxic varieties of jatropha [32]. In addition to the more common toxic varieties, non-toxic varieties of Jatropha curcas that contain negligible amounts of phorbol esters are reported to exist in Mexico and Central America [24]. The jatropha tree starts producing seeds from the first year and continues producing seeds up to 50 years with up to three harvesting times per year [33]. Typical seed production levels up to 5 tons seeds per ha per year has been reported [8]. The seed yields and oil content are highly dependent on environmental conditions (temperature, altitude, rainfall, sunlight, soil conditions), genetics, plant age and plant management (use of pesticide and fertilizer, irrigation, plant density, etc.) [8,34].

Dry Jatropha curcas fruit contains about 30-40% hull and 60-70% seed. The fruits are 2.5 cm long, ovoid, and have 2–3 seeds [35]. The seed contains about 30-40% shell and 60-70% kernel with the weight of the seeds is about 0.45-0.86 g [36]. The oil content in jatropha seed is reported to be in the range of 29 to 37% by weight of the seed or from 44 to 62% weight of the kernel. The kernels are also rich in crude protein (22-35%) [36]. The oil contains 63.9-91.6% unsaturated fatty acids (Table 3) with an iodine value of 92-112 which classifies it as a semi-drying oil (partially hardens when the oil is exposed to air) [24,37]. A representative figure of Jatropha curcas tree can be seen in Figure 3.

Table 3 Fatty acid composition of jatropha oil [24]

Fatty acid composition Jatropha oil Myristic acid C14:0 0-0.1 Palmitat acid C16:0 14.1-15.3 Palmitoleic acid C16:1 0-1.3 Stearic acid C18:0 3.7-9.8 Oleic acid C18:1 34.3-45.8 Linoleic acid C18:2 29.0-44.2 Linolenic acid C18:3 0-0.3 Arachidic acid C20:0 0-0.3 Bahenic acid C22:0 0-0.2 Total Saturated 17.8-25.6 Total Unsaturated 63.3-91.6

Figure 3 Rpresentative figure of Jatropha curcas vegetable

All parts of the jatropha plant can be used for a wide range of purposes. The potencies of several parts of jatropha plant can be seen in Figure 4. The jatropha plant itself has

traditionally been used as a medicinal plant and as a live fence to reclaim land or to protect gardens and crops from grazing animals [31,33]. The non-edible jatropha oil can be used directly as fuel in lamps [38], stoves [39], and stationary or mobile diesel engines (pumps, mills, tractor and electricity generators) [33] and as raw material for the production of lubricants [40], alkyd resins (paints and varnishes) [41], candles, medicines, cosmetics and soaps [42]. It is reported that the use of a blend of 10% (v/v) jatropha oil with diesel fuel does not cause engine problems [35]. The oil also can be converted to a high-quality biodiesel fuel, usable in a compression ignition (CI) diesel engine [43,44]. Furthermore, the fuel properties of jatropha biodiesel fulfill the major specifications outlined in European (EN 14214) and American (US ASTM D 6751-02) standards [45].

Figure 4 Potential utilization of the jatropha plant (Modified from [24])

The economic evaluation has shown that the biodiesel production from jatropha is very profitable provided the rest of the plants can be converted and sold as valuable products [46]. The fruit hulls can be use as activated carbon [47] and bio-compost production [48]. The cake obtained after removing the oil from the seed or kernel can be used as as an organic fertilizer [35], a fermentation substrate in enzyme production [49], or as feedstock for biogas production [50]. Non-toxic varieties or detoxified press cake, can be used as 8

animal feed as it is rich in protein (48 - 64%) [32,36]. In addition, there are several potential applications of jatropha seed shell, for example as particle board [51], activated carbon [52], pyrolysis oil [53] fuel for combustion units [54] and gasifier feedstock [55] which will add some economic value.

1.2 Vegetable oil processing

Jatropha oil processing involves the extraction and processing of oils from oilseed as shown in the general flow-scheme in Figure 5.

Figure 5 Schematic representations of “jatropha PPO production”; superscripts: the corresponding chapter numbers in this thesis

To successfully produce jatropha PPO or the bio-diesel derived from it, many factors play a role. The scheme illustrates the flow from harvested plant material to the final PPO product and the possible processes that can or have to be applied. In this section, the available literature regarding these processing steps will be summarized and analyzed, while the characteristics that determine the initial and longer term quality, i.e. stability, and performance of the oil will be summarized in the subsequent section. Each topic summarizes the current state of art and also highlights the unknowns and the research questions that will be dealt with in this thesis.

1.2.1 Growing conditions and harvesting

The seed yields are highly dependent on environmental conditions (temperature, altitude, rainfall, sunlight, soil conditions), genetics, plant age and plant management (use of pesticide and fertilizer, irrigation, plant density, etc) [8,34,57,58]. At low input condition, the dry jatropha seed yield is in the range of 2-3 tons/ha/yr. In more favorable conditions dry jatropha seeds yield up to 5 tons/ha/yr have been achieved [8]. Srivastava et al. (2011) [58]

studied the effect of growth performance on morphological characterization of seeds and seed oil content.

The harvesting time is one of the critical steps in seeds production. Oil content has been related to fruit maturity. The jatropha seed can be classified into four maturity stages: early maturity (green fruit), physiological maturity (yellow fruit), over maturity (brown fruit), and senescence (black-dry fruit). The best fruit maturity stage for seed oil content was found in yellow and brown fruit [59]. It is recommended that seed should be harvested at low moisture content [60]. But if the seeds are harvested at high moisture content, seeds should be dried immediately.

1.2.2 Drying and storage

Fresh jatropha seeds are usually has a moisture content of approximately 75% d.b. [61]. Therefore drying the seeds is necessary to reduce the moisture content of fresh harvested seed to a level that inhibits the biochemical, chemical and microbiological deterioration. This allows safe storage over an extended period and provides optimum conditions for next processing. Other objectives of drying are to substantially reduce weight and volume, minimize packaging, storage and transportation costs and enable storability of the product under ambient temperatures [62]. Drying must not impair the quality of the extracted oil. During the drying process, the constituents in the seeds can undergo undesirable reactions which cause loss of quality. The major deterioration of the seeds is due to lipid peroxidation and lipid hydrolysis [63]. Some other negative effects of hot air drying methods on the structure of some biological materials: changes such as shell cracking, color changes, cellular shrinkage, endosperm damage, or protein denaturalization [64].

Proper handling and storage of oil-containing materials are very important to minimize deterioration and maintain good quality of both contained oil and cake residue. There are several factors that influence rate of deterioration during seed storage: initial moisture content, temperature and humidity. The safe moisture content of seed for storage varies between 3-9% d.b., with lower moisture content for seeds with higher oil content [65]. Moisture contents in the range of 7.9 – 8.4% w.b. are reported as safe for storage of jatropha seeds up to five months inside plastic bags under ambient room conditions (24.4- 29.1 °C; 46-85.4% RH) [66].

1.2.3 Pretreatment before extraction

In industry, oilseeds undergo extensive preparation prior to extraction. Preparation may consist of a number of steps, such as cleaning, deshelling, moisture conditioning, cracking or

flaking and heat treatment [67]. Oilseeds need to be cleaned to remove foreign material such as plant stalk, debris or low quality seeds. Most oilseeds need to be separated from their outer husk or shell prior to oil extraction since husk and shells of oilseeds do not contain a significant amount of oil (less than 1 percent). Preparing and reducing the seed is to break down or weaken the oil-cell walls and also to expose a greater area of oil-bearing cells to the moisture and heat during heat treatment. Flaking facilitates oil release by decreasing the distance that the oil will have to travel to reach the particle surface. Heat treatment is essential because it completes the rupture of remaining cells to release oil, lowers the viscosity of the oil, coagulates the protein for better diffusion during extraction. Moisture conditioning of seed conducted to increases plasticity and adjusts the moisture content of the seed to the optimum level for extraction. These steps are usually necessary to enhance oil yield. Each type of oilseed requires a specific method of pretreatment [68].

1.2.4 Oil extraction

Oilseed processing and oil extraction processes are designed to obtain high quality oil with minimal undesirable components, achieve high extraction yields and produce high value cake. The choice of extraction method depends on the nature of the raw material, the oil content of the material, the level of allowable residual oil in the cake, the extent of protein denaturation allowed, product application and scale of production [69]. The maximum level of oil that can be extracted from a given sample of seed depends on the method of extraction. Industrial extraction of oil from seeds in general is carried out by two processes – solvent and mechanical extraction. Both approaches have their advantages and disadvantages with respect to scale of operation, centralization, extraction efficiency, and environmental and health risks. For seed with high oil content (above 35%) such as, flaxseed, safflower, sunflower seeds, groundnuts, palm kernels, rapeseed, and cottonseed, both steps are involved. Whereas, materials with lower oil content, such as soybeans and rice bran, can be directly solvent extracted [70]. Solvent extraction provides a high oil recovery, but co-extraction of non-triglyceride components requires an additional refining process [71]. It also requires a rigorous and energy intensive solvent recovery to reduce the volatiles level in both oil and cake [72,73]. Mechanical extraction is simpler and generally preferred because of its lower investment and operational cost. It can also be operated by semi-skilled personnel and produces relatively good quality oil, and it enables the use of the cake residue [74]. However, a disadvantage of mechanical extraction is the lower oil recovery compared to solvent extraction. It has been reported that solvent extraction with n-hexane could achieve about 90-99% oil recovery, against a maximum of 60-90% for mechanical extraction. The most efficient mechanical extraction may lead to some 5-7% of residual oil remaining in the cake [68,75]. Other extraction methods such as supercritical

CO2 extraction [76], aqueous extraction [77] with or without enzyme pretreatment [78] can be carried out for oil extraction.

Table 4 Comparison of extraction methods

Process Mechanical Aqueous Solvent SC-CO2 Extraction Extraction Extraction Extraction Oil Yield 60- 90% 40-80% 90-99% 90-99% Oil quality Low to Medium Pa Medium P Low to High Pb Low P Medium FFA Medium FFA Medium FFA Low FFA Medium OS Medium OS Low to medium OS Low OS Cake quality Protein (NSI) High Medium Low Medium Oil residue 7-17% 10-20% <1% <1% Scale production Small to medium Medium to Large Large Medium to Large Energy requirement Low Medium Large Medium Total Cost Low Medium - High High High a Cold press gave lower phosphorus content than hot pressed b Depends on the solvent used. Hexane extraction gives higher phosphorus content than alcohol extraction c FFA – free fatty acid, P – phosphorus content, OS – oxidative stability

1.2.5 Oil purification

The crude oil that is extracted from the oilseeds is a mixture of FFA, mono-, di-, and triglycerides, phosphatides, carbohydrate, protein, pigments, sterols and tocopherols. Trace amounts of metals, oxidation products, flavor and odor compounds may also be present. There are two basic methods in oil refining: chemical refining, and physical refining. These methods are basically different and based on free fatty acid removal. In chemical refining, FFA is removed by neutralization using alkali solution. Meanwhile in physical refining, FFA is removed by steam stripping. Chemical refining is suitable for oil with low FFA content and high phosphorus while physical refining is suitable for oils with high FFA content and low phosphorus level [70,79].

Degumming

Degumming is the first stage in oil refining process, and it is used to precipitate metal salts (phosphatides, carbohydrates, protein and mucilaginous materials likely to cause the oil to develop flavors and odors [70]. Phospholipids should be removed because of their strong emulsifying action and can join with pro-oxidant metal as they cause the problems during next refining step and storage [80], biodiesel production [81] and when it burn in diesel engine [82]. Table 5 show degumming methods of vegetable oil.

Table 5 Degumming processes in vegetable oils

Methods Principle Ref Water degumming Treatment of crude oil with hot water/steam; the gums for lecithin [83] production Acid degumming Treatment of crude/water degummed oil with acid solution, the gums for [84] animal feed Acid refining / Special Treatment of crude oil/water degummed oil with acid solution, then [85] degumming partially neutralized with alkali S.O.F.T. degumming Degumming using chelating agent (EDTA) [86] Ethanolamine Treatment with di-ethanolamine, simultaneous degumming and [87] degumming deacidification

Electrolyte degumming Treatment with electrolyte solution [88] Enzymatic degumming Modification of phospholipids with enzymes to facilitate the hydration [89] Membrane Passage of crude oil through a semipermeable membrane retaining [90] degumming phospholipids

Supercritical CO2 Extraction of phospholipid by supercritical CO2 [91] degumming

Deacidification

The deacidification purpose is to remove non-triglyceride impurities, consisting principally of FFA, along with substantial quantities of mucilaginous substances, phospholipids and coloring pigments [70]. Chemical, physical and miscella deacidification are general method for deacidification and have been used industrially. Table 6 shows features and limitations of deacidification methods [92].

Table 6 Methods of Deacidification [92]

Features Limitations Chemical deacidification (neutralization) Versatile––produces acceptable quality oil from all Excessive loss of neutral oil with high-FFA crude oil types of crude oil Neutral oil loss due to hydrolysis, saponification, Multiple effects––purifying, degumming, neutralizing emulsification, water washing and partially decolorizing the oils

Physical deacidification (steam stripping) Suitable for high-FFA oil Pretreatments are very stringent Low capital and operating costs Not suitable for heat sensitive oil––e.g., Greater oil yield cottonseed oil Chances of thermal polymerization Miscella deacidification Lower strength of caustic solution Higher investment––totally enclosed and Increased efficiency of separation explosion-proof equipment Minimum oil occlusion in soapstock Solvent loss––requires careful operation and Superior color of final product greater maintenance Water washing eliminated More suitable for integrated extraction and refining plant Cost intensive––homogenization necessary for effective neutralization and decolorization For efficient operation oil conc. in miscella should be 50% (two-stage solvent removal) Biological deacidification A. Employing whole-cell microorganism that Linoleic acid and short-chain FA (C no. <12) not selectively assimilate FFA e.g., Pseudomonas strain utilized; they inhibit microbe growth BG1 FA utilization depends on its water solubility B. Enzyme re-esterification––Lipase re-esterification High cost of enzyme Increased oil yield Low-energy consumption Mild operating conditions Re-esterification (chemical modification) With or without the aid of catalyst Random re-esterification Suitable for high-FFA oil Thermal polymerization Increased oil yield Costly process Solvent deacidification Extraction at ambient temperature and atmospheric Higher capital cost pressure Energy intensive operation Easy separation––large difference between boiling Incomplete deacidification (TG solubility increases points of solvent and fatty compounds with FFA in feed) Supercritical fluid extraction (SCFE) High selectivity, Low temp. and pollution free Costly process Suitable for a wide range of FFA oils Minimum oil losses

Membrane deacidification Low-energy consumption Molecular weight difference between TG and FFA Ambient temperature operation is small for separation No addition of chemicals Non-availability of suitable membrane with high Retention of nutrients and other desirable selectivity components Low permeate flux

1.2.6 Oil stabilisation

Plant oils have a relatively short storage life as they are slowly oxidized by atmospheric oxygen. Plant oils are more reactive to oxidation compared to petroleum oil which is due to the presence of unsaturation in the fatty acid chain. Oxidative stability of plant oils is mainly influenced by chemical structure of fatty acids, especially the unsaturation fatty acid degree [93]. Other factors such as temperature, oxygen content, light exposure, heavy metal compounds, water and pro-oxidant also have great influence on the formation of peroxides, acids, volatile compounds, and insoluble polymers during aging [94].

Antioxidants are used to improve the stability of plant oils by delaying oxidation and thermal degradation of plant oils. There are many types of antioxidants commonly used in oil and fat-based products. Chain Breaking Antioxidants are commonly called primary antioxidants. These types of antioxidants inhibit lipid oxidation by interfering with either chain propagation or initiation [95]. Chain breaking antioxidants are capable of donating hydrogen to lipid, alkoxy and peroxy radicals and convert them to more stable non-radical products. These antioxidants have higher affinities for peroxy radicals than other lipid radicals and react predominantly with peroxy radicals [96]. These antioxidant radicals can stabilize themselves through hybridization and do not promote or propagate further oxidation [97]. In addition, these antioxidant radicals are capable of participating in termination reaction with peroxy, oxy and other antioxidant radicals.

Other types of antioxidants are preferred to be named as secondary antioxidants. They do not convert free radicals into stable molecules. They act as chelators for pro-oxidants or catalyst metal ions (EDTA, citric acid, and phosphoric acid derivatives), decompose hydroperoxides to non-radical compounds (phosphorus and sulphur based antioxidants), provide hydrogen atoms to primary antioxidants, deactivate singlet oxygen (carotenoids), absorb ultraviolet radiation (carbon black, phenylsalicylate), or act as oxygen scavengers (ascorbic acid and erythorbic acid). They often enhance the antioxidant activity of chain breaking antioxidants [96].

1.3 Product quality

1.3.1 Problems in using vegetable oil as fuel

There are several problems associated with using pure plant oil (PPO) as fuel in normal diesel engines. These problems can be divided into two classes. The first class, operation problems, includes ignition quality characteristics, e.g. poor cold engine start-up, misfire, and ignition delay. The second class is durability problems such as deposit formation, carbonization of injector tips, ring sticking and lubricating oil dilution. These are mainly due

to the high viscosity of vegetable oils which leads to poor fuel atomization and inefficient mixing with air, which contributes to incomplete combustion. One severe problem associated with the use of vegetable oils as fuels is carbon deposits. Low oxidative stability and contaminants such as phosphorus, free fatty acid, water and sediment also contribute to durability problems of the engine. Problems in using vegetable oils with probable cause and potential solutions are presented at Table 7.

Table 7 Problems associated as using vegetable oil as fuel [modified from 82]

Properties Problems Solutions Viscosity Poor cold engine starting Preheat the oil, add cold flow improver, chemical modification Phosphorus, Plugging and gumming of filters, Refine the oil (degumming) ash lines and injectors Cetane Engine knocking, ignition delay Preheat the oil, chemical number modification Viscosity carbon deposits, nozzle coking, Heat the oil, blend with diesel, excessive engine wear, chemical modification contamination of lubricating oil Oxidative Polymerisation causes deposition Add antioxidant, processing stability on the injector, filter plugging, control, maintain storage ring sticking, engine wear, condition, proper packaging thickening of lubricating oil material. Acid value Corrosiveness and oil instability Refine the oil (deacidification) Phosphorus Form deposits, filter plugging, Refine the oil (degumming) abrasive Water Form deposits, corrosiveness, Refining and filtering, drying filter plugging, oil instability Note: One Example of chemical modification is trans-esterification

1.3.2 Oil quality parameters

Vegetable oil is obtained by pressing the seeds of the plants and may contain some impurities. For a number of applications (e.g. fuel), the oil needs further refining to meet the quality criteria. DIN V 51605-10 is used in Germany as a trading standard for rape-seed oil as fuel. It is the only existing quality standard for fuel-grade straight vegetable oil which lists 15 fuel parameters with corresponding testing methods and limiting values (Table 8). A high oil quality is essential to ensure the trouble-free engine use. A standardized fuel quality is an

important precondition for assessment of operational and emission characteristics, as well as engine performance.

Table 8 Quality standard for rapesed oil fuel Standard DIN 51605:2010-10

Limiting value Properties Unit Testing methods min max Visual Inspection - Limpid, no free water visible, - no contaminations visible Density at 15 oC kg/m3 910 925 DIN EN ISO 3675 or DIN EN ISO 12185 Kinematic viscosity at 40 oC mm2/s - 36 DIN EN ISO 3104 Calorific value MJ/kg 36 - DIN 51900-1, -2, DIN 51900-1, -3 Iodine number g I/ 100g 125 DIN EN 14111 Flash Point °C 101 - DIN EN 2719 Ignition Quality - 40 DIN EN 15195 Oxidative stability at 110 oC h 6 - DIN EN 14112 Acid value mg KOH/g - 2 DIN EN 14104 Total Contamination mg/kg - 24 DIN EN 12662:1998-10 Sulphur content mg/kg - 10 DIN EN ISO 20884 or DIN EN ISO 20886 Phosphorus content mg/kg - 3 DIN EN 51627-6 Calsium content mg/kg - 1 DIN EN 51627-6 Magnesium content mg/kg - 1 DIN EN 51627-6 Water content % (m/m) - 0.075 DIN EN ISO 12937

There are a number of important parameters which determine the capability of plant oil as a diesel fuel substitute. These parameters can be divided into two categories. The first one concerns characteristic parameters that depend on the feedstock used, while the second category concerns the properties that depend on the processing technology used. Characteristic properties include density, viscosity, flash point, calorific value, iodine number and ignition quality. Meanwhile, variable properties include total contamination, oxidative stability, phosphorus content, acid value, ash content and water content. These variable properties are needed to be controlled to meet the specification of the standard.

1.3.3 Critical product performance requirements

High quality oil requires a minimum content of acid value (free fatty acid), phosphorus and moisture in the oil and has a high oxidative stability. The purity and composition of the oil affect the engine performance. Generally, the lower the oxidative stability and the higher the content of free fatty acids (FFA), water, phosphorus, and other contaminants, the more engine problems occur.

The acid value is an indicator of the content of free fatty acids in plant oil. FFA are virtually absent in fats/ oils of living tissue and mainly formed due to enzyme (lipase) action after the oilseed has been harvested. It is known to be affected by the oil processing, duration and conditions of storage of the oil. Free fatty acids are formed due to hydrolysis of triglycerides especially when enough water is present in the oil. Hydrolysis of ester bonds in oil resulting in the liberation of FFA, may be caused by enzyme action or by heat and moisture [98]. The release of short-chain fatty acids by hydrolysis is responsible for the development of an undesirable rancid flavor (hydrolytic rancidity). Furthermore, FFAs are more susceptible to oxidation than the corresponding triglycerides; and this lipid oxidation, leads to further oxidative rancidity in vegetable oils. Therefore, any increase in the acidity of the oil must be absolutely avoided [92]. A high acid value in the fuel leads to corrosion, abrasion and deposits in the engine. Furthermore the free fatty acids may react with the alkaline components of the lubricating oil and affect its lubricity [99].

The phosphorus content is an indicator of phospholipids which are the major component of cell membrane. Phospholipids commonly found in vegetable oil include phosphatidyl choline, phosphatidyl inositol, phosphatidyl serine, phosphatidyl ethanolalamine. Meanwhile, phosphatidic acids are mainly produced by enzymatic hydrolysis of phospholipids. The molecule is acidic and bears a negative charge and thus requires a counter ion. The presence of calcium and magnesium in crude oil can form salts with phosphatidic acid. Phosphatidic acids and salts are not present in native oils but are generated during the post-harvest stage. The levels depend upon the quality of oilseed (unripe, damaged, or moist seeds), storage and extraction process [100].

Phospholipids should be removed because of their strong emulsifying action and because they can join with pro-oxidant metal. Presence of phospholipid in plant oil or biodiesel also causes problems in diesel engines such as plugging and gumming of fillters, lines and injectors [82]. Phosphorus reduces the combustion temperature, leads to deposits in the combustion chamber and eventually changes the emission behavior. The life and efficiency of catalytic converters are affected by the presence of phosphorus compounds. Furthermore phospholipids tend to form particles with water and can cause filter blockage [99].

High water content leads to crystal growth at low temperatures and hence causes filter blockage. Because of the high pressures in modern injection systems, free water is released that could damage the injection system. At the boundary layer between water and fuel, the growth of micro-organisms is promoted which can block the fuel filter and promote the ageing process [99]. In addition, water can cause corrosion in fuel lines [82]. In plant oils the water content is influenced by seed moisture, refining process parameters, condensation effects and water uptake during storage [99].

Oxidative stability is an indicator of oil stability during storage and harsh processing. Oxidative stability affects biodiesel primarily during extended storage. It is mainly influenced by the degree of unsaturation. The higher the degree of unsaturation, the more susceptible the fatty oils are to oxidation. Processing conditions such as temperature, oxygen content, light exposure, heavy metal compounds, pro-oxidant and antioxidant content as well as nature of the storage container also exert a great influence on oxidative rate of the vegetable oils [101,102]. Vegetable oils with low oxidative stability demonstrate increased acidity, viscosity, and more insoluble impurities during aging [103]. The resulting oxidation products can in particular damage the fuel injection system of machines or vehicle motors, by forming deposits. Harmful interactions between the fuel and the engine lubricating oil also become more likely [99].

1.4 Thesis Outline

This research is aimed to deliver effective, economically feasible oil processing to produce jatropha oil with a high and consistent quality to meet product specification requirements, but still enable the proper usage of the protein-rich cake from which the oil has been extracted. Therefore, it is required to study different technical approaches to extract the oil, and to develop processing /product property relationships that enable the design of extraction and purification units that deliver excellent and consistent fuel performance.

The primary objective of this thesis is the achievement of optimum oil extraction levels without deteriorating the product performance characteristics as delivered by nature. The second objective is to develop extraction and purification technology that produces pure oil of consistent and undisputable quality. The third objective is to develop extraction technology that still enables the subsequent use of the protein-rich matrix from which the oils have been extracted.

In this study, drying condition will be investigated, seed pressing technology will be optimized, alternative oil recovery procedures will be explored (e.g. solvent-assisted mechanical extraction), purification of oils will be established and the stabilization of oils will

be optimized. Jatropha oil has to meet a number of critical quality criteria (i.e. phosphor and acid value, oxidative stability) to be applied as a diesel substitute.

In Chapter 2, the drying characteristics of jatropha in both seed and kernel are compared and discussed. The effect of drying parameters, including air-drying temperature, on several quality parameters of crude jatropha oil were evaluated in terms of acid value, phosphorus content and oxidative stability.

In Chapter 3, the influence of process parameters on oil recovery from jatropha kernel are investigated in more detail. The rate of pressure build-up, applied pressure, moisture content of sample, pressing temperature, duration of pressing, feedstock size reduction, shell removal and preheating time were studied as variables, and the quality of the obtained oils was evaluated.

In Chapter 4, the most important pressing parameters obtained from chapter 3 were further optimized to maximize the oil yield. This approach used the face centered central composite design response surface method. The non-linear model was generated and predicted the best condition to maximize oil yield. The experimental validation was conducted and the quality of the obtained oils was evaluated.

In Chapter 5, the effect of solvent assisted pressing was evaluated in order to maximize oil yield. Renewable solvents were used: bio-ethanol and bio-butanol. The purity of solvent, solvent to feed ratio, pressure, temperature and time were studied as variables, and the quality of the obtained oils was evaluated.

In Chapter 6, purification of jatropha oil was studied. The effect of purification parameters including purification agent, concentration and temperature on several quality parameters of crude jatropha oil were evaluated in terms of acid value, phosphorus content and oxidative stability on batch scale. The best condition was applied in a novel continuous process in a CCS unit, and the quality of the obtained oils was evaluated.

In Chapter 7, the stabilization of jatropha oil was evaluated. Various antioxidants were studied to postpone the oxidation of the oil. The Oxidative Stability Index was analyzed and maximized as a quality parameter for the stabilization of jatropha oil.

References

[1] U.S. Energy Information Administration (EIA), Petroleum and other liquid. http://www.eia.gov/dnav/pet/pet_pri_fut_s1_d.htm (Accessed Date: 25 October 2014). [2] Demirbas,A., 2009. Progress and recent trends in biodiesel fuels. Energy Conversion and Management 50, 14–34. [3] European Union, 2009. Directive 2009/28/EC of the European Parliament and of the Council: on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC; 23 April 2009. [4] Schuman,S., 2010. Improving China’s Existing Renewable Energy Legal Framework: Lessons from the International and Domestic Experience. Natural Resources Defense Council. [5] Peraturan Presiden Republik Indonesia No. 5 tahun 2006 tentang Kebijakan Energi Nasional. psdg.bgl.esdm.go.id/kepmen.../perpres%20no5%20tahun%202006.pdf (Accessed Date: 25 October 2014). [6] Emerging market online Biodiesel 2020: Global market survey, feedstock trends and forecast, http://www.emerging-markets.com/biodiesel/ (Accessed Date: 25 September 2011). [7] ANSI/ASABE S593 MAY2006, Terminology and Definitions for Biomass Production, Harvesting and Collection, Storage, Processing, Conversion and Utilization, American Society of Agricultural and Biological Engineers, 2006. [8] Achten,W.M.J., Verchot,L., Franken,Y.J., Mathijs,E., Singh,V.P., Aerts,R., and Muys,B., 2008. Jatropha bio-diesel production and use. Biomass and Bioenergy 32, 1063–1084. [9] Demirbas,A., 2002. Diesel fuel from vegetable oil via transesterification and soap pyrolysis. Energy Sources 24, 835–841. [10] Choe,E., and Min,D.B., 2006. Mechanisms and factors for edible oil oxidation. Comprehensive Reviews in Food Science and Food Safety 5, 169-186. [11] Ali,Y., and Hanna,M.A., 1994. Alternative diesel fuels from vegetable oils. Bioresource Technology 50, 153-163. [12] Srivastava,A., and Prasad,R., 2000. Triglycerides-based diesel fuels. Renewable and Sustainable Energy Reviews 4, 111–133. [13] Kim,H., and Choi,B., 2010. The effect of biodiesel and bioethanol blended diesel fuel on nanoparticles and exhaust emissions from CRDI diesel engine. Renewable Energy 35, 157– 163. [14] Monyem,A., and Gerpen,J.H.V., 2001. The effect of biodiesel oxidation on engine performance, Biomass and Bioenergy 20, 317–325. [15] Tan,R.R., Culaba,A.B., and Purvis,M.R.I., 2004. Carbon balance implications of coconut biodiesel utilization in the Philippine automotive transport sector. Biomass Bioenergy 26, 579–585. [16] Hossain,A.K., and Davies,P.A., 2010. Plant oils as fuels for compression ignition engines: A technical review and life-cycle analysis. Renewable Energy 35, 1–13. [17] Clark,S.J., Wagner,L.W., Schrock,M.I., and Piennaar,E.G., 1984. Methyl and ethyl soybean esters as renewable fuels for diesel engines. Journal of the American Oil Chemists' Society 61, 1632-1638. [18] Guzman,A., Torres,J.E., Prada,L.P., and Nuñez,M.L., 2010. Hydroprocessing of crude palm oil at pilot plant scale. Catalysis Today 156, 38-43. 21

[19] Yusaf,T.F., Yousif,B.F., and Elawad,M.M., 2011. Crude palm oil fuel for diesel-engines: Experimental and ANN simulation approaches. Energy 36, 4871-4878. [20] Demirbas,A., 2003. Chemical and fuel properties of seventeen vegetable oils. Energy Sources 25, 721–728. [21] Agarwal,D., and Agarwal,A.K., 2007. Performance and emissions characteristics of jatropha oil (preheated and blends) in a direct injection compression ignition. Applied Thermal Engineering 27, 2314–2323. [22] Pramanik,K., 2003. Properties and use of Jatropha curcas oil and diesel fuel blends in compression ignition Engine. Renewable Energy 28, 239–248. [23] Pinzi, I.L., Garcia, F., Lopez-Gimenez, J., Luque de Castro, M.D., Dorado, G., and Dorado M.P., 2009. The Ideal Vegetable Oil-based Biodiesel Composition: A Review of Social, Economical and Technical Implications. Energy and Fuels 23, 2325–2341. [24] Gübitz,G.M., Mittelbach,M., and Trabi,M., 1999. Exploitation of the tropical oil seed plant Jatropha curcas L. Bioresource Technology 67, 73–82. [25] Achten,W.M.J., Mathijs,E., Verchot,L., Singh,V.P., Aerts,R., and Muys,B., 2007. Jatropha biodiesel fueling sustainability? Biofuels, Bioproduction and Biorefining 1, 283–291. [26] Becker, K., and Makkar,H.P.S., 2008. Jatropha curcas: A potential source for tomorrow's oil and biodiesel. Lipid Technology 20, 104-107. [27] Pandey,V.C., Singh,K., Singh,J.Y., Kumard, A., Singh,B., and Singh, R.P., 2012. Jatropha curcas: A potential biofuel plant for sustainable environmental development. Renewable and Sustainable Energy Reviews 16, 2870–2883 [28] USDA Foreign Agricultural service, Oilseeds: World Market and Trade, 2014. [29] Chhetri, A.B., Tango, M.S., Budge, S.M., Watts, K.C., and Islam, M.R., 2008. Non-Edible Plant Oils as New Sources for Biodiesel Production. International Journal Molecular Science 9, 169-180. [30] Hill,A., Al Kurki and Morris,M., 2010. Biodiesel: The Sustainability Dimensions. ATTRA Publication. Butte, MT: National Center for Appropriate Technology.p 4-5. [31] Heller,J., 1996. Physic nut Jatropha curcas L. Promoting the conservation and use of underutilized and neglected crops, Institute of Plant Genetics and Crop Plant Research, Gartersleben. International Plant Genetic Resources Institute, p 13. [32] Makkar,H.P.S., and Becker,K., 2009. Jatropha curcas, a promising crop for the generation of biodiesel and value-added coproducts. European Journal of Lipid Science and Technology, 111, 773-787. [33] Openshaw,K., 2000. A review of Jatropha curcas: an oil plant of unfulfilled promise. Biomass and Bioenergy 19, 1–15. [34] Wen,Y., Tang,M., Sun,D., Zhu,H., Wei,J., Chen,F., and Tang,L., 2012. Influence of Climatic Factors and Soil Types on Seed Weight and Oil Content of Jatropha Curcas in Guangxi, China. Procedia Environmental Sciences 12, 439-444. [35] Singh,R.N., Vyas, D.K., Srivastava, N.S.L., and Narra, M., 2008. SPRERI experience on holistic approach to utilize all parts of Jatropha curcas fruit for energy. Renewable energy 33, 1868- 1873. [36] King,A.J., He,W., and Cuevas,J.A., Freudenberger, M., Ramiaramanana, D., and Graham, I.A., 2009. Potential of Jatropha curcas as a source of renewable oil and animal feed. Journal of experimental botany 60, 2897-2905.

[37] Akintayo,E.T., 2004. Characteristics and composition of Parkia biglobbossa and Jatropha curcas oils and cakes. Bioresource Technology 92, 307-310. [38] Chakraborty,N., and Sarkar,S.C., 2008. Development of a biofuel lamp and its comparison with a kerosene lamp. Journal of Energy in Southern Africa 19, 22-24. [39] Natarajana,R., Karthikeyana,N.S., Agarwaal,A., and Sathiyanarayanan,K., 2008. Use of vegetable oil as fuel to improve the efficiency of cooking stove, Renewable Energy 33, 2423– 2427. [40] Resul,M.F.M.G., Ghazi,T.I.M., and Idris,A., 2012. Kinetic study of jatropha biolubricant from transesterification of jatropha curcas oil with trimethylolpropane: Effects of temperature. Industrial Crops and Products 38, 87–92. [41] Odetoye,T.E., Ogunniyi,D.S., and Olatunji,G.A., 2010. Preparation and evaluation of Jatropha curcas Linneaus seed oil alkyd resins. Industrial Crops and Products 32, 225–230. [42] Kumar,A., and Sharma,S., 2008. An evaluation of multipurpose oil seed crop for industrial uses (Jatropha curcas L.): A review. Industrial Crops and Products 28, 1-10. [43] Kumar,M.S., Ramesh,A., and Nagalingam,B., 2003. An experimental comparison of methods to use methanol and jatropha oil in a compression ignition engine. Biomass and Bioenergy 25, 309-318. [44] Banapurmath,N.R., Tewari,P.G., and Hosmath,R.S., 2008. Performance and emission characteristics of a DI compression ignition engine operated on Honge, jatropha and sesame oil methyl esters. Renewable energy 33, 1982-1988. [45] Azam,M.M., Waris,A., and Nahar,N.M., 2005. Prospects and potential of fatty acid methyl esters of some non-traditional seed oils for use as biodiesel in India. Biomass and Bioenergy 29, 293-302. [46] Foidl,N., and Eder,P., 1997. Agro-industrial exploitation of Jatropha curcas. In: Gubitz, G.M., Mittelbach, M., Trabi, M. (Eds.), Biofuels and Industrial Products from Jatropha curcas. DBV Graz, p 88-91. [47] Tongpoothorn,W., Sriuttha,M., Homchan,P., Chanthai,S., and Ruangviriyachai, C., 2011. Preparation of activated carbon derived from Jatropha curcas fruit shell by simple thermos chemical activation and characterization of their physico-chemical properties chemical Engineering research and design 89, 335–340. [48] Sharma,D.K., Pandey,A.K., and Lata, 2009. Use of Jatropha curcas hull biomass for bioactive compost production. Biomass and bioenergy 33, 159–162. [49] Mahanta,N., Gupta,A., and Khare,S.K., 2008. Production of protease and lipase by solvent tolerant Pseudomonas aeruginosa PseA in solid-state fermentation using Jatropha curcas seed cake as substrate. Bioresource Technology 99, 1729-1735. [50] Staubmann,R., Foidl,G., Foidl,N., Gübitz,G.M., Laferty,R.M.,and Arbizu,V.A.V. and Steiner, W., 1997. Biogas Production from Jatropha curcas Press-Cake. Applied Biochemist and Biotechnology 63, 457-467. [51] Wever,D.A.Z., Heeres,H.J., and Broekhuis,A.A., 2012. Characterization of Physic nut (Jatropha curcas L.) shells. Biomass and Bioenergy 37, 177-187. [52] Kumar,R., and Namasivayam, 2009. Development and charactheristic of activated carbons from jatropha husk, an agroindustrial solid waste, by chemical activation methods. Journal of Environmental Engineering and Management 19, 173-178. [53] Manurung,R., Wever,D.A.Z., Wildschut,J., and Heeres,H.J., 2009. Valorisation of Jatropha curcas L. plant parts: Nut shell. Food and bioproducts processing 87, 187-196.

[54] Kratzeisen,M., and Müller,J., 2013. Suitability of jatropha seed shells as fuel for small-scale combustion units. Renewable energy 51, 46-52. [55] Vyas,D.K., and Singh,R.N., 2007. Feasibility study of jatropha seed husk as an open core gasifier feedstock. Renewable energy 32, 512-517. [56] Pandey,V.C., Singh,K., Singh,J.Y., Kumar,A., Singh,B., and Singh,R.P., 2012. Jatropha curcas: A potential biofuel plant for sustainable environmental development. Renewable and Sustainable Energy Reviews 16, 2870–2883. [57] Van Eijcka,J., and Romijn,H., 2008. Prospects for jatropha biofuels in Tanzania: An analysis with Strategic Niche Management, Energy Policy 36, 311–325. [58] Srivastava,P., Behera,S.K., Gupta,J., Jamil,S., Singh,N., and Sharma,Y.K., 2011. Growth performance, variability in yield traits and oil content of selected accessions of Jatropha curcas L. growing in a large scale plantation site. Biomass and bioenergy 35, 3936-3942. [59] Santoso,B.B., Budianto,A., and Aryana,I.G.P.M., 2012. Seed viability of Jatropha curcas in different fruit maturity stages after storage. Nusantara Biosience 3, 113-117. [60] Silip,J.J., Tambunan,A.H., Hambali,E., Sutrisno,E.H., and Surahman,M., 2010. Extracted oil yield and biomass changes during on-tree maturation, ripening and senescence of Jatropha curcas Linn. fruits. European Journal of Scientific Research, 44, 602-609. [61] Sirisomboon,P., Kitchaiya,P., Pholpho,T., and Mahuttanyavanitch,W., 2007. Physical and mechanical properties of Jatropha curcas L. fruits, nuts and kernels. Biosystem Engineering 97, 201-207. [62] Mujumbar,A.S., 1995. Handbook of industrial drying (2ed). New York: Marcel Dekker. [63] Bax,M.M., Gely,M.C., and Santalla,E.M., 2004. Prediction of crude sunflower oil deterioration after seed drying and storage processes. Journal of the American Oil Chemists' Society 81, 511-515. [64] Perea-Flores,M.J., Garibay-Febles,V., Chanona-Pérez, J.J., Calderón-Domínguez,G., Méndez- Méndez,J.V., Palacios-González,E., and Gutiérrez-López,G.F., 2012. Mathematical modelling of castor oil seeds (Ricinus communis) drying kinetics in fluidized bed at high temperatures. Industrial Crops and Products 38, 64–71. [65] Vertucci,C.W., and Roos,E.E., 1990. Theoretical Basis of Protocols for Seed Storage, Plant Physiology 94, 1019-1023. [66] Worang,R.L., Dharmaputra,O.S., and Syarief,R., 2008. The quality of physic nut (Jatropha curcas L.) seeds packed in plastic material during storage. BIOTROPIA 15, 25-36. [67] Dunford,N.,Oil and Oilseed Processing I. Food and Technology Fact Sheet 405-744-6071. [68] Carr.,R. 1993. Oilseed Harvesting, Storage and Transportation. In: Proceedings of the World Conference on Oilseed Technology and Utilization. Editor T.H. Applewhite. AOCS Press, Champaign, IL. [69] Dunford,N.,Oil and Oilseed Processing II. Food and Technology Fact Sheet 405-744-6071. [70] Gunstone,F.D., 2004. The chemistry of oil and fats: source, composition, properties and uses. Blackwell Publishing, CRC press. [71] Gandhi,A.P., Joshi,K.C., Jha,K., Parihar,V.S., Srivastav,D.C., Raghunadh,P., Kawalkar,J., Jain,S.K., and Tripathi,R.N. 2003. Studies on alternative solvents for the extraction of oil-l soybean. International journal of food science & technology 38, 369-375. [72] Russin,T.A., Boye,J.I., Arcand,Y., and Rajamohamed,S.H., 2011. Alternative techniques for defatting soy: a practical review. Food and Bioprocess Technology 4, 200-223.

[73] Venter,M.J., Willems,P., Kuipers,N.J.M., and Haan,A.B., 2006. Gas assisted mechanical expression of cocoa butter from cocoa nibs and edible oils from oilseeds. The Journal of Supercritical Fluids 37, 350-358. [74] Olajide,J.O., Igbeka,J.C., Afolabi,T.J., and Emiola,O.A., 2007. Prediction of oil yield from groundnut kernels in an hydraulic press using artificial neural network (ANN). Journal of food engineering 81, 643-646. [75] Bargale,P.C., Ford,R.J., Sosulski,F.W., Wulfsohn,D., and Irudayaraj,J., 1999. Mechanical oil expression from extruded soybean samples. Journal of the American Oil Chemists' Society 76, 223-229. [76] Boutin,O., and Badens,E., 2009. Extraction from oleaginous seeds using supercritical CO2: Experimental design and products quality, Journal of Food Engineering 92, 396–402. [77] Cater,C.M., Rhee,K.C., Hagenmaier,R.D., and Mattil,K.F., 1974. Aqueous extraction—An alternative oilseed milling process, Journal of the American Oil Chemists Society 51, 137-141 [78] Domínguez,H., Núñez,M.J., and Lema,J.M., 1994. Enzymatic pretreatment to enhance oil extraction from fruits and oilseeds: a review Food Chemistry 49,271–286. [79] O'Brien,R.D., 2008. Fats and Oils: Formulating and Processing for Applications, 3rd ed. CRC press, 80-82. [80] Wan, P.J., and Wakelyn,P.J., 2005. Solvent extraction to obtain edible oil products. In Handbook of Functional Lipids. ed Akoh, C.C., CRC press, p 113. [81] Van Gerpen,J.H., and Dvorak,B., 2002. The effect of phosphorus level on the total glycerol and reaction yield of biodiesel. Bioenergy. The 10th Biennial Bioenergy Conference, Boise, ID, Sept. 22–26, 2002. [82] Ma,F., and Hanna,M.A., 1999. Biodiesel production: a review, Bioresource Technology 70, 1- 15. [83] Ceci,L.N., Constenla,D.T., and Crapiste,G.H., 2008. Oil recovery and lecithin production using water degumming sludge of crude soybean oils. Journal of the Science of Food and Agriculture 88, 2460–2466. [84] Pan,L.G., Campana,A., Tom,M.C., and An,M.C., 2000. A Kinetic Study of Phospholipid Extraction by Degumming Process in Sunflower Seed Oil. Journal of the American Oil Chemists' Society 77, 1273–1276. [85] Dijkstra,A.J., and Van Opstal,M., 1989. The Total Degumming Process. Journal of the American Oil Chemists' Society 66, 1002-1009. [86] Choukri,A., Kinany,M.A., Gibon,V., Tirtiauc,A., and Jamil,S., 2001. Improved Oil Treatment Conditions for Soft Degumming. Journal of the American Oil Chemists' Society 78, 1157– 1160. [87] Zufarov,O., Schmidt,S., Sekretár,S., and Cvengro,J., 2009. Ethanolamines used for degumming of rapeseed and sunflower oils as diesel fuels. Eur. J. Lipid Sci. Technol. 111, 1-8. [88] Nasirullah, 2005. Physical refining electrolyte degumming of NHP from selected vegetable oils. Journal of Food Lipids 12, 103–111. [89] Clausen,K., 2001. Enzymatic oil-degumming by a novel microbial phospholipase. Eur. J. Lipid Sci. Technol. 103, 333–340. [90] Koris,A., and Vatai,G., 2002. Dry degumming of vegetable oils by membrane filtration, Desalination 148, 149–153.

[91] List,G.R., King,J.W., Johnson,J.H., Warner,K., and Mounts,T.L., 1993. Supercritical CO2 degumming and physical refining of soybean oil, Journal of the American Oil Chemists’ Society 70, 473-476. [92] Bhosle,B.M., and Subramanian, R., 2005. New approaches in deacidification of edible oil –a review, Journal of food engineering 69, 481-494. [93] Knothe,G., 2002. Structure indices in fatty acid chemistry. How relevant is the iodine value? Journal of the American Oil Chemists’ Society 79,847-854. [94] Waynick,J.A., 2005. Charactherization of biodiesel oxidation and oxidation products, CRC Project No. AVFL-2b Southwest Research Institute. [95] Frankel,E.N., 1998. Lipid Oxidation. The Oily Press, 13-41, 129-160. [96] Wanasundra,P.K.J.P.D., and Sahidi,F., 2005. Antioxidant: Science, technology and applications. In Bailey’s industrial oil and fat products, 6thed, volume 6. Shahidi, F., eds. Wiley. Washington. [97] Buck,D.F., 1981. Antioxidants in Soya Oil, Journal of the American Oil Chemists’ Society 58, 275-278. [98] Nawar,W.W., 1996 Lipids, In Food Chemistry. Fennema,O.R., Eds. Marcel Dekker Inc., New York, 255-287. [99] Rice,B., Fogarty,C., Leahy,J.J., Rourke,B.O., 2006. Quality assurance for rape-seed oil as vehicle fuel. Begley Hutton, Sustainable Energy Ireland, Dublin. [100] Hammond,E.G., Johnson,L.A., Su,C. Wang,T., and White,P.J., 2005. Soybean Oil In Bailey’s industrial oil and fat products, 6thed, volume 6. Shahidi,F., eds. Wiley. Washington. [101] Knothe,G., 2007. Some aspects of biodiesel oxidative stability. Fuel Processing Technology 88, 669-677. [102] Choe,E., and Min,D.B., 2006. Mechanisms and factors for edible oil oxidation. Comprehensive Reviews in Food Science and Food Safety 5, 169-186. [103] Mittelbach, M., and Gangl,S., 2001. Long storage stability of biodiesel made from rapeseed and used frying oil.Journal of the American Oil Chemists’ Society 78, 573–577.