FATS and OIL TECHNOLOGY 2024 PDF

FATS and OIL TECHNOLOGY 1 2 3 4 5 Our dietary intake comprises three macronutrients (protein, carbohydrate and lipid) and a large but unknown number of micronutrients (vitamins, minerals, antioxidants, etc.). Good health rests, in part, on an adequate and balanced sup...

FATS and OIL TECHNOLOGY 1 2 3 4 5 Our dietary intake comprises three macronutrients (protein, carbohydrate and lipid) and a large but unknown number of micronutrients (vitamins, minerals, antioxidants, etc.). Good health rests, in part, on an adequate and balanced supply of these components Oil bearing materials used as raw materials in fats and oils manufacturing may be of either plant (seed or fruit) or animal (land or marine animal) origin. 6 ▪ Plants used to produce edible products: Soybean, cottonseed, sunflower seed, safflower seed, corn germ, peanut, olive, rice bran, rapeseed, canola, coconut, palm fruit, and carob. ▪ Animal sources and animal fat products: Cattle, sheep, pigs, fish Butter, lard, tallow, whale oil and fish oil. 7  In TURKEY Main raw materials used for oil manufacturing process are: cottonseed sunflower seed rapeseed (canola) olive 8  vegetable oils Most vegetable oils are obtained from beans or seeds, which generally furnish two valuable commodities—an oil and a protein-rich meal. Seed extraction is achieved by pressing and/or by solvent extraction. Oils such as palm and olive, on the other hand, are pressed out of the soft fruit (endosperm). Seeds give oils in different proportions. soybean (18.3%); rapeseed (38.6%); sunflower (40.9%); groundnut (40.3%); cottonseed (15.1%); coconut (62.4%); Palm kernel (44.6%); sesame (42.4%); linseed (33.5%); from palm fruit (45–50%) olive (25–30%) corn (about 5%) are as indicated. 9 10  Examples of Saturatd Fatty Acids Common Chemical C:D name structure CH3(CH2)6CO Caprylic acid 8:0 OH CH3(CH2)8CO Capric acid 10:0 OH CH3(CH2)10CO Lauric acid 12:0 OH CH3(CH2)12CO Myristic acid 14:0 OH CH3(CH2)14CO Palmitic acid 16:0 OH CH3(CH2)16CO Stearic acid 18:0 OH Arachidic CH3(CH2)18CO 20:0 acid OH CH3(CH2)20CO Behenic acid 22:0 OH Lignoceric CH3(CH2)22CO 24:0 acid OH CH3(CH2)24CO Cerotic acid 26:0 OH 11 12 13  SUNFLOWER SEED Healthy, natural sunflower oil is produced from oil type sunflower seeds. Sunflower oil is light in taste and appearance and supplies more Vitamin E than any other vegetable oil. It is a combination of monounsaturated and polyunsaturated fats with low saturated fat levels. There are three types of sunflower oil available; mid-oleic,, linoleic and high oleic sunflower oil. All are developed with standard breeding techniques. They differ in oleic levels and each one offers unique properties. 14 sunflowers 15 ▪ High oleic sunflower oil High oleic sunflower oil is very high in oleic (monounsaturated) acid. High oleic sunflower oil is usually defined as having a minimum 80 percent oleic acid. The oil provides excellent stability without hydrogenation. High oleic sunflower oil offers a trans free oil solution for some customers. The oil has many uses including bakery applications, spray coating oils for cereal, crackers and dried fruit; it is used in non-dairy creamers, many types of frying and other uses. 16 COTTONSEED OIL 17  COTTONSEED Like the name suggests, cottonseed oil is extracted from cottonseed. Cottonseed is mainly an unsaturated oil, as 70% of this oil is unsaturated (18% monounsaturated (oleic acid), and 52% polyunsaturated (from linoleic acid). Cottonseed oil is often preferred over many other oils that would have to be hydrogenated (like soybean oil). 18 Physical properties Once processed, cottonseed oil has a mild taste and appears generally clear with a light golden color, the amount of color depending on the amount of refining. It has a relatively high smoke point as a frying medium. Like other long-chain fatty acid oils, cottonseed oil has a smoke point of about (232 °C) and is high in tocopherols, which also contribute its stability, giving products that contain it a long shelf life, hence manufacturers' proclivity to use it in packaged goods. Use in food Cottonseed oil has traditionally been used in foods such as potato chips and is a primary ingredient in the shortening products. But since it is significantly less expensive than olive oil or canola oil, cottonseed has started to creep into a much wider range of processed foods, including cereals, breads and snack foods. Products that say "may contain one or more of these oils" and list cottonseed, virtually always contain it. Cottonseed oil resists rancidity, so offers a longer shelf life for food products in which it is an ingredient. 19 SOYBEAN OIL 20  SOYBEAN The soybean (U.S.) or soya bean (UK) is a species of legume native to East Asia. The oil and protein content together account for about 60% of dry soybeans by weight; protein at 40% and oil at 20%. The remainder consists of 35% carbohydrate and about 5% ash.. 21 Soybean is the dominant oilseed produced in the world, due to its favorable agronomic characteristics, its high-quality protein, and its valuable edible oil. It contributes over a half of all oilseeds produced worldwide 22 23 Production To produce soybean oil, the soybeans are cracked, adjusted for moisture content, heated to between 60 and 88 °C, rolled into flakes, and solvent-extracted with hexanes. The oil is then refined, blended for different applications, and sometimes hydrogenated. Soybean oils, both liquid and partially hydrogenated are sold as "vegetable oil," or are ingredients in a wide variety of processed foods. Most of the remaining residue (soybean meal) is used as animal feed. 24  Soybean composition Protein 40 % Oil (dry basis) 20 % Cellulose and hemicellulose 17 % Sugars 7% Crude fiber 5% Ash (dry basis) 6 % 25 RAPESEED OIL (CANOLA OIL) kolza tohumu 26  RAPESEED Traditionally, rapeseed is used for birdseed or industrial purposes. Industrial varieties of rapeseed contain about 55 percent erucic acid and are used to make lubricants and diesel fuel substitutes and to manufacturer plastics.These varieties have high levels of toxic glycosinolates along with high erucic-acid levels, which renders the processed meal unsuitable for human or livestock consumption. New varieties of rapeseed, developed in Canada and Europe, are low in erucic acid and glycosinolates. These varieties are the so-called “double low” types and sometimes are marketed as Canola. The extracted oil is used as an edible vegetable oil. Domestic markets are expected to increase because previousrestrictions are being relaxed. 27 CORN OIL 28  CORN GERM Corn oil is oil extracted from the germ of corn (maize). Its main use is in cooking, where its high smoke point makes it a valuable frying oil. It is also a key ingredient in some margarines. One bushel of corn contains 3% of oil. Corn agronomists have developed high-oil varieties, however, these varieties tend to show lower field yields, so they are not universally accepted by growers. Refined corn oil is 99% triglyceride, with proportions of approximately 59% polyunsaturated fatty acid, 24% monounsaturated fatty acid, and 13% saturated fatty acid. Corn oil is also one source of biodiesel. Other industrial uses for corn oil include soap, paint, rustproofing for metal surfaces, inks, textiles, and insecticides. It is sometimes used as a carrier for drug molecules in pharmaceutical preparations. 29 HAZELNUT OIL 30  HAZELNUT ▪ Hazelnuts are rich in protein and unsaturated fat. Moreover, they contain significant amounts of thiamine and vitamin B6, as well as smaller amounts of other B vitamins. ▪ Hazelnut oil, pressed from hazelnuts, is strongly flavoured and used as a cooking oil. 31 ▪ In the fatty acid composition of hazelnut oil, there is around 71-91% of oleic acid. ▪ Hazelnut oil also contains linoleic acid at a rate of around 2-21%. ▪ Hazelnut oil is rich in calcium and vitamin E. 32 OLIVE OIL 33  OLIVES ▪ The Olive (Olea europaea) is a species of small tree in the family Oleaceae, native to coastal areas of the eastern Mediterranean region, from Syria and the maritime parts of Asia Minor and northern Iran at the south end of the Caspian Sea. Its fruit, the olive, is of major agricultural importance in the Mediterranean region as the source of olive oil. 34 Extraction of olive oil from olives Virgin olive oil is obtained from the fruits of the olive tree (Olea europaea) by mechanical or other physical means, under conditions that do not cause any changes in the oil. The oil is first released from the olives by crushing: in pressure systems, stone mills are generally used and in continuous centrifugation plants, metal crushers (hammer, roller, disc). After it has been crushed the olive paste is mixed. Malaxation (stirring the olive mass slowly and constantly) lasts about 30 minutes. The main constituents of the paste after malaxation are olive oil, small pieces of kernel (pit), water and cellular debris. Separation is achieved by pressure, centrifugation, or selective filtration processes. Important factors in the production of good quality olive oil are the harvesting period, maturity of the fruit, the mode of harvesting (hand picking, nets, other means), storage of olives before processing, leaf removal, mode of crushing and kneading, and the system of extraction. 35 1- Pressure (SIZMA) Pressure is the oldest method of extraction. It is still in use though not widespread. It was largely replaced in the 1970s and 1980s by centrifugation methods, which helps to cut processing costs and to reduce olive storage time. In the pressure system, the paste is pressed to release an oily must (oil and water from the olives). The liquid separates from the solid phase through drainage. A cake (pomace) is formed between the mats and this is dried and used for the production of olive residue oil. Oil and water are further separated by centrifugation Pressure systems yield good quality oil when the fruits themselves are in good condition and the filtering diaphragms are properly cleaned. Otherwise, oils are produced with a high level of undesirable components, such as n- octane, 2-methyl-propanol, 3-methylbutanol and acetic acid. 36 37 2- Centrifugation (three phase system) The crushed olives are mixed with water. A horizontal centrifuge separates the mass into pomace and must and the latter is further separated into oil and water 38 3- Two phase decanters Water is not added in two phase decanter extraction. The crushed olives are directly separated into oil and a mixture of water and husks. This system reduces significantly the amount of waste water and so protects the environment. The oil produced is more stable because the level of natural antioxidants is higher. However, the pomace has a high moisture content (57– 58%) and this makes its transportation more costly. 39 40 Extraction of pomace oil (olive-residue oil) Mechanical processsing of olive paste leaves two residual products: husks (pomace) and water. Residual oil in the pomace varies depending on the mode of extraction. It is usually 6–8% in pressure systems and 3–5% in the three phase extraction systems. The recovery of the oil from the husks is achieved by extraction with hexane. This is undertaken in plants at another location, involving transportation of the byproduct, which presents a cost problem because of its high moisture content (25–58%). The raw oil extracted from the husks is dark green, with high acidity and a bad flavour. It has to be neutralised, bleached, and deodorised before it is edible. Due to the solvent extraction, olive-residue oil contains some minor constituents at higher levels than those found in olive oils (waxes, sterols, erythrodiol and uvaol). This is the reason for designating pomace oil as a distinct product. 41 42 prina yağı olive pomace oil yemeklik rafine prina yağı refined olive pomace oil natürel birinci zeytinyağı virgin olive oil natürel ikinci zeytinyağı ordinary virgin olive oil natürel sızma zeytinyağı extra virgin olive oil 43 The descriptions and definitions given below are included in EU regulation 356/1992 based on the 1986 International Agreement of Olive Oil and Table Olives adopted by olive oil producing countries. Virgin olive oil. The oil obtained from the fruit of the olive tree (Olea europaea) only by mechanical or other physical means under conditions, particularly thermal, that do not lead to alteration in the oil and which has not undergone treatment other than washing, decantation, centrifugation and filtration. Extra virgin olive oil. This type has absolutely perfect flavour and odour, and a maximum acidity, in terms of oleic acid, of 1 g/100 g. Fine virgin olive oil. This type has absolutely perfect flavour and odour, and a maximum acidity, in terms of oleic acid, of 2 g/100 g. Semi-fine virgin olive oil (or ordinary virgin olive oil). This type has good flavour and odour, and a maximum acidity, in terms of oleic acid, of 3.3 g/100 g, with a 10% margin of tolerance.. 44  Virgin olive oil not fit for consumption as it is. This oil, designated virgin olive oil lampante, is intended for refining or for technical purposes. It has an off-flavour and/or off-smell and acidity, in terms of oleic acid, of more than 3.3 g/100 g. Refined olive oil. This oil, which is obtained from virgin olive oil by refining methods which do not lead to alteration in the initial triacylglycerol structure, has a maximum acidity, in terms of oleic acid, of 0.5 g/100 g. Olive oil. This oil, which consists of a blend of virgin olive oil (except lampante) and refined olive oil, has a maximum acidity, in terms of oleic acid, of 1.5 g/100 g. Crude olive pomace oil (crude olive residue oil). This oil, to the exclusion of oils obtained by re-esterification processes and any mixture with oils of other kind, is obtained by treating olive pomace with solvents. Refined olive pomace oil. This oil, which is obtained from crude olive pomace oil by refining methods not altering the initial triacylglycerol structure, has acidity of no more than 0.5 g/100 g. Olive pomace oil. This oil, which is a mixture of refined olive residue oil and virgin olive oil (except lampante), has a maximum acidity, in terms of oleic acid, of 1.5 g/100 g 45  PALM OIL The oil palm (Elaeis guineensis jacquin) originated from South Africa. It was introduced to East Asia as an ornamental plant, planted at the Bogor Botanical Garden Java (Indonesia) in 1884. 46  The dark red-orange colour of oil palm fruit is due to the high concentration of carotenoids and anthocynanins. Crude palm oil, extracted commercially by sterilisation and press, contains 400–1000 ppm of carotenoids, the variation being due to process conditions, species of oil palm and level of oxidation. 47 Composition and properties of palm oil and fractions Palm oil has a balanced fatty acid composition in which the level of saturated fatty acids is almost equal to that of the unsaturated fatty acids. Palmitic acid (44–45%) and oleic acid (39–40%) are the major component acids along with linoleic acid (10–11%) and only a trace amount of linolenic acid. The low level of linoleic acid and virtual absence of linolenic acid make the oil relatively stable to oxidative deterioration. 48 Palm oil is unique among vegetable oils in having a significant amount of saturated acids (10–15%) at the 2-position of its TAGs. The appreciable amounts of disaturated (POP and PPO) and monosaturated (POO, OPO and PLO) are apparent as high-melting and low- melting fractions Iodine value, also called Iodine Number, in analytical chemistry, measure of the degree of unsaturation of an oil, fat, or wax; the amount of iodine, in grams, that is taken up by 100 grams of the oil, fat, or wax Palm oil, a semi-solid at ambient temperature (25–30◦C), may be fractionated into a liquid fraction (olein) and a more solid fraction (stearin). 49 Food applications of palm oil products Palm oil is one of the major oils in the world oils and fats. Almost 90% of this oil is used as edible products in many applications, such as cooking/frying oils, margarines, shortenings, vanaspati, speciality fats and spray dried products. A large variety of possible product formulations can be made with either palm oil alone or in combination with palmkernel oil/fractions or with other vegetable oils. Its composition confers oxidative stability, having very little polyunsaturated acid. Being naturally semi-solid in nature, there is little necessity for hydrogenation. Palm olein is much used as a cooking oil, domestically and in industrial outlets. Palm oil and its fractions are accepted as frying oils for food products such as snack chips, crackers, cookies, pastries, doughnuts, fries and instant noodles. Frying, being a thermal process, results in rapid deterioration of oil. The oxidative stability of palm oil, olein, and stearin is a major advantage of the oils. Free fatty acid content is one of the parameters used for evaluating the quality of frying oils. During frying, there is less formation of free acids when palm olein is used or blended with other vegetable oils 50 Margarine is a flavoured product containing 80% fat blended with water, and containing vitamins and other ingredients. Initially developed to replace dairy butter, it now appears in a variety of types including regular, whipped, soft-tub, liquid, diet, spreads, low- calorie, bakery and speciality. Today’s margarines incorporate nutritional as well as functional properties and cater for the requirements of different consumers. The properties of margarines depend on the characteristics of the oil forming the major ingredient of the product. The solid fat content of the oil at a range of temperatures is an indicator of the crystallization properties of the finished product. Palm oil is suited for industrial margarines, having 23% solids at 20◦C. 51 Shortening was the term used to described the function performed by naturally occurring solid fats, such as lard and butter, in baked foods. It is now generally applied to fat products which can affect the emulsification, lubricity, structure, aeration, flavour and heat-transfer of prepared foods. Palm oil, a semi-solid fat, is highly suited to this purpose and its tendency to form β crystals is an advantage as such crystals provide better aeration in batters than β forms. Unlike margarines, shortenings are entirely oils and fats (100%) though some may have small amounts of emulsifiers added. Figure shows the solid content of palm oil products which can be incorporated with other oils to be used as shortenings. Blends of soft stearin with palm oil give products with the solid content required of a shortening. 52 Crude Oil Production 53  Extraction of Vegetable Oils Basic approaches : ▪ Mechanical Oil Extraction - cold pressing means no heat applied - hot pressing - external heat is applied ▪ Solvent Extraction - organic solvent (hexane, isopropyl alchool) - supercritical solvent (carbondioxide) 54  Mechanical oil extraction Mechanical oil extraction (expression) is a solid-liquid phase seperation method which is applied to cooked seed flakes. It can be executed by batch, mainly hydraulically, and by continous, mainly mechanically, working presses. 55  Screw presses; In oil industry, screw presses (expellers) are mostly utilized for expression. The main parts of continous-screw press are; ▪ Seed feeder, ▪ Cone-shaped cage ▪ Adjustable cone for press-cake outlet ▪ Worm (pressure and feed) 56 Cooked seed flakes Screw press Adjustable cone for press- cake outlet knife Cone shaped pressure cage Main worm shaft cake Crude oil 57 The seeds enter the barrel and falls on the helical pressure worm. During movement in the barell, between worm and cage is gradually reduced and the seed flakes are subjected to increasing pressure. The cage is made of a number of special stell bars which let liquids pass through. The oil passes between the bars an flows out of the cage. The cone moves along the shaft of the expeller and the space between the worm and cone can be regulated. This permits easy control of the thichnesses of cakes and of the degree of pressure to which the cooked flakes are subjected. 58 Screw Press 59 Shaft Arrangement-- Screw Press 60  Crude oil production (mechanical expression) Cooked flakes Screw press Crude oil + seed particles Cake (4-6%oil) Crude oil seed particles 61  Solvent extraction (solid-liquid extraction-leaching) The lowest levels of residual oil after pressing are 3-8%; exhaustive removal of the oil present in the cake by mechanical means alone is imposible. The residual oil in cake , therefore, only be removed by a different approach, this being solvent aided extraction. 62  Single stage leaching miscella V1 Solvents V0 Seed flakes + solvents flakes L0 Cake L1 L0 + V0 = L1 + V1 63 ▪ Basic principles of solvent extraction: The extraction of oil from oilseeds by means of non-polar solvents is, basically, a process of solid-liquid extraction. The transfer of oil from the solid to the surrounding oil-solvent solution ( miscella ) may be divided into three steps: diffusion of the solvent into the solid dissolution of the oil droplets in the solvent diffusion of the oil from the solid particle to the surrounding liquid 64  * The rate of extraction can be increased considerably by increasing the temperature in the extractor. Higher temperature means higher solubility of the oil, higher diffusion coefficients and lower miscella viscosity. * An open, porous structure of the solid material is preferable, because such a structure facilitates diffusion. 65 A typical commercial solvent for oil extraction would have a boiling point range (distillation range) of 65 to 70oC and would consist mainly of six-carbon alkanes, hence the name "hexane“ by which these solvents are commonly used in oil extraction. 66  Types of Extractors Solvent extractors are of two types: ▪ batch ▪ continuous In batch processes, a certain quantity of flakes is contacted with a certain volume of fresh solvent. The miscella is drained off, distilled and the solvent is recirculated through the extractor until the residual oil content in the batch of flakes is reduced to the desired level. 67  Batch extractor Seed flakes solvent cake miscella 68  In continuous extraction, both the oilseeds and the solvent are fed into the extractor continuously. The different available types are characterized by their geometrical configuration and the method by which solids and solvents are moved one in relation to the other, in counter-current fashion. 69 Desolventizer 70 CRUDE OIL REFINING PROCESS 71 72  Refining of crude oil Crude oils as received from the extraction plant contain several non-triglyceride components which must be removed. Refining consists of several processes which accomplish this aim. 73  Depending on the requirements, the following basic processes are implemented: ▪ degumming for removal of phosphatides, ▪ neutralization for removal of free fatty acids, ▪ bleaching for removal of color, ▪ deodorization to distill odors and flavors as well as free fatty acids and ▪ winterization for separation of waxes. 74  Refining Methods Chemical Refining ▪ Degumming ▪ Neutralizing ▪ Bleaching ▪ Deodorization Physical Refining ▪ Degumming ▪ Bleaching ▪ Steam distillation 75 76 77 78  Degumming The aim of degumming operation; ▪ The emulsifying action of phospholipids increases oil losses during alkali refining. ▪ Gums lead brown discoloration of oil after heating during deodorization. ▪ Salts may be formed with cooper, magnesium,calcium and iron, accelerating oxidative degredation of oil. ▪ Certain phospholipids, such as lecithin, find widespread industrial application. 79 Phospholipid Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid bilayers. Phosphatidylcholine (lecithine) 80  Different degumming processes are carried out to remove phosphatides. For efficient and economic application of this procedure appropriate machines and equipments are used. ▪ Water degumming ▪ Acid degumming ▪ Enzymatic degumming ▪ Membrane degumming 81  Crude palm oil Degumming equipment Crude corn oil Refined corn oil 82  Water Degumming Process Steps Heat oil to 60 -70 °C Water addition and mixing Hydration mixing 30 minutes Centrifugal separation of hydrated gums Vacuum drying of degummed oil Gums -dried for edible lecithin or recombined in meal 83  Water Degumming Phosphorous in degummed oil -50 to 200 ppm max Moisture in dried and degummed oil -< 0.1%. reactor mixer vacuum water Vacuum dryer steam gums heater seperator to storage 84  Acid degumming Dry acid degumming: Dry acid degumming is particularly suit-able for processing oils with low gum contents such as palm oil, coconut oil, palm kernel oil or animal fats. Intensive mixing is implemented following addition of acid to the pre- heated crude oil. The conditioned gums are absorbed into the bleaching earth and are separated by filtration. The benefits of the dry acid degumming process are: ▪ Efficiency as a result of ▪ low energy consumption, ▪ low operation and maintenance costs (sturdy and reliable control system), ▪ long service life (the components are acid proof), ▪ low investment costs, ▪ environmental-friendly as no wastewater or soap stock occur. 85  Enzymatic degumming Enzymatic degumming was first introduced by the German Lurgi Company as the »Enzy Max process«.The EnzyMax process can be divided into four different steps: (i) the adjustment of the optimal conditions for the enzyme reaction, i.e. optimal pH with a citrate buffer and the optimal temperature; (ii) the addition of the enzyme solution; (iii) the enzyme reaction; (iv) the separation of lysophosphatide from the oil at about 75 °C. Enzymes for enzymatic degumming; ▪ Lecitase® 10L (pancreatic phospholipase A2) ▪ Lecitase® Novo (microbial lipase) ▪ Lecitase® Ultra (microbial lipase) 86  NEUTRALISATION Objective:Removal of free fatty acids Two different refining principles: 1.Chemical Refining:Removal by a chemical reaction with alkali(caustic soda) 2. Physical Refining:Removal by distillation at higher temperature and low vacuum 87  Batch Neutralization: Refining of vegetable oils is essential to ensure removal of gums, waxes, phosphatides and free fatty acid (F. F.A.) from the oil; to impart uniform colour by removal of colouring pigments and to get rid of unpleasant smell from the oil by removal of odiferous matter. Refining is carried out either on batch operation or as continuous operation. With certain oils even physical refining can be carried out instead of chemical. 88 89  BLEACHING Bleaching is one of the key processes in fats and oils refining, designed to remove not only pigments, but also a wide range of other impurities. Most crude fats and oils contain impurities that have to be removed for both commercial and health reasons. Modern industrial bleaching technologies are the way to do this The bleaching of fats and oils is normally carried out after either alkaline refining or degumming, and prepares the oil for the final deodorization process. In the case of crude palm oil, bleaching is the initial stage of the whole refining process. 90  BLEACHING Bleaching earth 91 At first glance, bleaching is a relatively simple process that consists of mixing the oil with a powder, stirring for some minutes and then removing the powder again. Efficient bleaching makes it possible to remove certain pigments such as carotinoids and chlorophyll decompose and partially remove oxidation products remove contaminants such as soaps and trace metals remove traces of phosphatides remove polycyclic aromatic hydrocarbons and other pollutants. All these substances can have adverse effects on both the quality and stability of your final product, and therefore have to be removed to ensure that the product is commercially attractive. 92 Bleaching agents (example activated betonites) The most commonly used way to bleach fats and oils is to treat them with surfactant powdery materials. These bind (also known as “adsorb”) the pigmented substances in the oils to the extensive surface area provided by them being in powder form. 93  DEODORIZTION Deodorization, usually the last step in oil refining, is a steam-stripping process in which good-quality steam (1–3% of oil), generated from de- aerated and properly treated feed water, is injected into soybean oil under high temperature (252–266◦C) and high vacuum (