CHAPTER FAT & OIL.pdf

# Production methods of fats and oils Fats and oils are extracted from various sources using three primary methods: rendering, pressing/expelling, and solvent extraction. ## 1. Production methods of fats and oils There are a few basic production methods to obtain fats and oils from animal, marine, and vegetable sources. These methods include rendering, pressing or expelling, and solvent extraction, which are then followed by various refining and modifying procedures [3](#page=3). ### 1.1 Rendering Rendering is a process used to obtain fats from animal sources. Lard is obtained from hogs or pigs, and tallow is obtained from beef. The process involves heating meat scraps or fatty animal tissues to melt the fat, causing the melted fat and water to rise while the remaining tissues settle. The melted fat is then separated through skimming or centrifugation [5](#page=5). #### 1.1.1 Types of rendering There are two main types of rendering: * **Dry heat rendering:** This method cooks the tissue under a vacuum to remove moisture [7](#page=7). * **Wet rendering:** This method utilizes hot water or steam to melt out the fatty tissues [7](#page=7). #### 1.1.2 Rendering temperature considerations The temperature used during rendering influences the characteristics of the obtained fat. A lower rendering temperature generally results in a lighter fat color. Conversely, a higher rendering temperature tends to yield a more pronounced meaty flavor [8](#page=8). ### 1.2 Pressing or expelling Pressing or expelling is a mechanical method used to extract oil from oilseeds. Various types of mechanical presses and expellers are employed for this purpose. Before pressing, the seeds are typically cooked slightly, ground, or cracked to break down their cell structure and melt the fat, facilitating easier oil release [9](#page=9). > **Tip:** Excessive heat during the preparation for pressing can lead to the extraction of pigments, resulting in a darker oil color [9](#page=9). The oil obtained through pressing or expelling is often further clarified by pumping it through multiple cloths within a filter press. It is important to note that mechanical pressing alone does not extract 100% of the oil present in the seeds; a residual amount of 3-8% typically remains [11](#page=11) [9](#page=9). ### 1.3 Solvent extraction Solvent extraction is employed to recover a greater amount of oil than what can be achieved through pressing alone. Since mechanical means cannot remove all the oil from seeds, leaving a residual level of 3-8% solvent extraction becomes necessary to maximize oil yield [11](#page=11). #### 1.3.1 Characteristics of an ideal solvent An effective solvent for oil extraction should possess several key characteristics [12](#page=12): * It should have a narrow and not excessively high boiling point or range, ideally around 85-86 degrees Celsius, and remain liquid at very low temperatures [12](#page=12). * The solvent should be neutral to the oil, dissolving it easily and selectively [12](#page=12). * It must be stable and inert when in contact with metal surfaces [12](#page=12). * A low specific heat, a low heat of evaporation (the heat required to evaporate the solvent, not its temperature), and a low viscosity and density are desirable [12](#page=12). * The solvent should be insoluble in water [12](#page=12). * It should be non-toxic [12](#page=12). * Availability in adequate quantities at low prices is also a crucial factor [12](#page=12). #### 1.3.2 Common solvents used Commonly used solvents for oil extraction include light petroleum hydrocarbons such as hexane, along with components like 2- and 3-methylpentane, 2,3-dimethylbutane, methyl-cyclopentane, and cyclohexane. Trichloroethylene is also a known solvent in this application [13](#page=13). #### 1.3.3 The solvent extraction method The solvent extraction method involves percolating the solvent through the oilseeds. After the oil has been extracted, the solvent is distilled and recovered for re-use. The remaining oil-free residual seed meal is then ground and typically used for animal feed. The processes of "percolation" and "distillation" are central to this extraction technique [14](#page=14) [15](#page=15) [16](#page=16). --- # Refining of crude oils Refining of crude oils aims to remove undesirable components through a combination of physical and chemical processes, maximizing the retention of valuable unaltered triacylglycerols, natural antioxidants, and vitamins [18](#page=18). ### 2.1 Undesirable components in crude oils Crude oils contain various components that need to be removed during refining to improve their quality and suitability for consumption or further processing. These include [19](#page=19): * Free Fatty Acids (FFAs) [19](#page=19). * Phosphoacylglycerols (gums) [19](#page=19). * Sterols [19](#page=19). * Pigments (e.g., chlorophyll) [19](#page=19). * Glucosides [19](#page=19). * Flavors (including aliphatic aldehydes and ketones) [19](#page=19). * Waxes [19](#page=19). * Heavy metals [19](#page=19). * Pesticides [19](#page=19). * Hydrocarbons [19](#page=19). ### 2.2 Conventional refining operations The conventional refining process typically involves four main steps: degumming, deacidification (alkali neutralization), bleaching (decolorization), and deodorization [20](#page=20). #### 2.2.1 Degumming Degumming is the process of removing phosphatides, which are gummy or slimy substances found in vegetable oils from pressing or solvent extraction. These phospholipids, when wetted with water, become insoluble and settle out [21](#page=21). ##### 2.2.1.1 Significance of degumming * The emulsifying action of phospholipids can lead to increased oil losses during alkali refining [22](#page=22). * Gums can cause brown discoloration of oil upon heating during deodorization [22](#page=22). * Certain phospholipids, like lecithin, have significant industrial applications, with soy bean oil being a primary source [21](#page=21) [22](#page=22). * Phospholipids can form salts with metals like copper, magnesium, calcium, and iron, which can accelerate oxidative degradation of the oil [22](#page=22). ##### 2.2.1.2 Types of gums There are two main types of gums: * **Hydratable Phosphatides:** These are easily removed [23](#page=23). * **Non-Hydratable Phosphatides (NHP):** These are harder to remove and may require the use of an acid to convert them into a hydratable form for complete removal [23](#page=23). ##### 2.2.1.3 Phospholipids structure and hydration Phospholipids consist of a phosphate group with varying attached groups (e.g., choline, inositol, ethanolamine, acid). The size and structure of these groups influence the hydratability of the phospholipid; larger groups increase hydratability. Hydrolysis of phospholipids to their lyso-form makes them more hydratable [25](#page=25) [26](#page=26). > **Tip:** Understanding the structure of phospholipids is key to comprehending their behavior during degumming. #### 2.2.2 Deacidification (alkali neutralization) Deacidification, also known as alkali neutralization, is the process of removing Free Fatty Acids (FFAs) from the oil. Besides triacylglycerides, crude oils contain dissolved FFAs, partial acylglycerols, residual phospholipids, and sterols. After gum removal, FFAs can be neutralized by adding an alkali [20](#page=20) [29](#page=29). ##### 2.2.2.1 Process of deacidification An aqueous caustic solution (lye), typically sodium hydroxide ($NaOH$), neutralizes the FFAs, forming salts called soaps. This process also saponifies some ester-type compounds. Deacidification helps remove residual phospholipids and body color. The formed soaps are then removed through centrifugation or filtration [30](#page=30). ##### 2.2.2.2 Methods of deacidification Various methods are employed for deacidification: * Caustic-based batch neutralization [32](#page=32). * Dilute caustic-based (semi) continuous neutralization [32](#page=32). * Strong caustic-based (semi) continuous neutralization [32](#page=32). #### 2.2.3 Bleaching or decolorization Bleaching, or decolorization, is performed to remove color from the oil. While degumming and neutralization can improve the color to some extent, crude oils often still contain plant pigments like chlorophyll and carotene, which need to be removed to meet market demands for lighter-colored oils. Bleaching is a standard part of both wet and dry refining operations [20](#page=20) [33](#page=33). ##### 2.2.3.1 Methods in bleaching Several methods are used for bleaching: * Adsorption on solids such as charcoal, adsorbent clay, or earth [34](#page=34). * Heating [34](#page=34). * Catalytic hydrogenation [34](#page=34). * Chemical bleaching agents [34](#page=34). > **Note:** Animal fats can generally be bleached by heat alone [34](#page=34). #### 2.2.4 Deodorization Deodorization is the final regular step in the refining process and involves stripping the oil with live steam at elevated temperatures and under reduced pressure [20](#page=20) [36](#page=36). ##### 2.2.4.1 Purposes of deodorization The primary purposes of deodorization are: * Removal of odoriferous volatile compounds [36](#page=36). * Removal of residual amounts of FFAs [36](#page=36). * Heat bleaching of carotenoids, especially if present in large amounts [36](#page=36). * Rendering of oils through chemical changes, leading to improved flavor stability during their shelf life [36](#page=36). ##### 2.2.4.2 Exceptions to deodorization In some fats and oils, odorous compounds are desirable and are not deliberately removed. Examples include olive oil, cocoa butter, lard, and fresh butterfat [37](#page=37). --- # Fat modification processes This section delves into the key processes used to modify the physical characteristics of fats and oils [39](#page=39). ### 3.1 Hydrogenation Hydrogenation is a process where hydrogen atoms are added to unsaturated fats to increase their firmness and texture. This process transforms liquid unsaturated fatty acids (FAs) by saturating some or all of their double bonds with hydrogen in the presence of a catalyst, typically finely dispersed nickel particles [40](#page=40) [41](#page=41). #### 3.1.1 Mechanism and effects of hydrogenation The core mechanism involves dissolving hydrogen into the unsaturated fat and promoting its reaction with double bonds. This process, also known as fat hardening, significantly alters the melting and solidification properties of the treated oils. By reducing the degree of unsaturation, hydrogenation also enhances the oil's stability against oxidation and improves its flavor profile. Once the desired level of hardening is achieved, unreacted hydrogen is removed from the converter via vacuum, and the nickel catalyst is separated through filtration. Hydrogenation is primarily employed in the production of solid shortenings and margarines from liquid oils [41](#page=41) [42](#page=42). > **Tip:** Hydrogenation creates trans fatty acids, which have similar properties to saturated fats but are associated with negative health outcomes [40](#page=40). #### 3.1.2 Trans fatty acids and health implications The excessive intake of trans fatty acids has been linked to adverse health effects, including an increase in low-density lipoprotein (LDL) cholesterol, a decrease in high-density lipoprotein (HDL) cholesterol, and an elevated risk of cardiovascular disease. Current recommendations suggest limiting trans fat intake to 3-4% of total daily calories [45](#page=45). > **Tip:** To minimize trans fat intake, limit the consumption of hydrogenated fats, deep-fried foods, high-fat baked goods, and non-dairy creamers [46](#page=46). ### 3.2 Fractionation Fractionation is a technique used to separate fats and oils into distinct fractions with differing physical properties, either to remove undesirable components or to isolate valuable ones. Historically, the fractionation of tallow into hard oleostearine and semi-solid oleomargarine (a precursor for margarine) was significant, though its importance has diminished with the advent of hydrogenation. With the large-scale production of palm oil, fractionation has become crucial for obtaining palm stearin (a higher melting solid fraction) and palm olein (a liquid fraction), both of which are composed of triacylglycerols (TAGs) [48](#page=48) [50](#page=50). > **Example:** Refined, Bleached, and Deodorised (RBD) Palm Stearin is a naturally hard fat used in shortenings and pastry margarines, with a melting point of 50–55 °C. RBD Palm Olein, refined, bleached, and deodorised palm olein, is used for cooking, frying, and as a food ingredient [51](#page=51) [52](#page=52). #### 3.2.1 Methods for fractionation There are three primary methods for fractionating fats and oils: * **Dry fractionation:** This method involves completely melting the fat and then cooling it with agitation until the higher melting fraction crystallizes. The crystallized stearin fraction is subsequently removed by filtration [54](#page=54). * **Solvent fractionation:** In this process, the fat is dissolved in a solvent, such as acetone or hexane. The warm solution is then cooled with agitation, causing the stearin fraction to precipitate, which is then removed by filtration. While more efficient than dry fractionation, the cost of organic solvents limits its application. It is commonly used to produce palm mid-fraction, a component of cocoa butter equivalents for chocolate [55](#page=55). * **Detergent or Lanza fractionation:** This technique utilizes an aqueous detergent solution to reduce the entrainment of the liquid fraction within the solid crystals during dry fractionation. Although it improves separation efficiency, the issue of effluent management has restricted its widespread use [56](#page=56). #### 3.2.2 Winterization Winterization is a specific type of fractionation crystallization applied to oils that contain glycerides with high melting points, which could cause cloudiness when the oil is chilled. The objective is to remove these higher-melting glycerides, ensuring the oil remains clear and bright even after refrigeration [57](#page=57). > **Example:** For salad oils, winterization involves gradually cooling the semi-refined or refined oil to the temperature at which it is expected to remain sediment-free. The oil is cooled at a controlled rate to approximately 6–7 °C and held for 8–12 hours. The crystallized material, known as stearin, is then removed by filtering and can be used in shortenings [58](#page=58). ### 3.3 Intraesterification Intraesterification is a process designed to create and concentrate triacylglycerols (TAGs) that possess more desirable physical properties than those obtained through other modification methods. Under the influence of a suitable catalyst, the component fatty acids (FAs) and glycerol moieties within the TAGs can detach from their original positions, redistribute, and re-esterify with new partners. This redistribution results in newly formed glycerides with altered physical and functional characteristics compared to the original fat. The appeal of this relatively simple process lies in its ability to modify both the melting characteristics and the crystallization behavior of fats and fat mixtures [60](#page=60). > **Tip:** Understanding the structure of a triacylglycerol molecule, consisting of a glycerol backbone esterified with three fatty acids, is fundamental to grasping intraesterification [61](#page=61). --- # Margarine production Margarine is a food product primarily made from edible fats and oils, forming a water-in-oil emulsion, designed as a milk-fat-free substitute [63](#page=63). ### 4.1 Composition of margarine Margarine is characterized by its fat and water content, along with other added ingredients that contribute to its taste, flavor, aroma, and physical, chemical, and nutritional properties [63](#page=63). #### 4.1.1 Fat and water content The fat content in margarine is generally regulated to be less than 80%, while the water content should not exceed 16% [63](#page=63). #### 4.1.2 Other ingredients Additional ingredients are incorporated to enhance the sensory and functional attributes of margarine. These ingredients can be categorized as either water-soluble or fat-soluble [64](#page=64). ##### 4.1.2.1 Water-soluble ingredients Water-soluble ingredients commonly include skim milk, salt, and permitted preservatives [64](#page=64). ##### 4.1.2.2 Fat-soluble ingredients Fat-soluble ingredients comprise natural coloring compounds, flavorings (such as butter flavor), lecithin, vitamins, antioxidants, emulsifiers, and stabilizers [64](#page=64). ### 4.2 Quality of ingredients The quality of the raw materials is crucial for producing high-quality margarine. #### 4.2.1 Fat bases Fats and oils used for margarine and shortening must be of edible quality, possessing good flavor, quality, and flavor stability [65](#page=65). #### 4.2.2 Water quality The water used must meet local chemical and hygienic standards for drinking water. If the water is too hard, it needs to be softened before use [65](#page=65). ### 4.3 Manufacturing process The production of margarine involves several key stages, starting with the preparation of mixtures and culminating in packaging. #### 4.3.1 Preparation of mixtures Two primary mixtures are prepared: one consisting of oil and oil-soluble ingredients, and the other comprising water and water-soluble ingredients [67](#page=67). #### 4.3.2 Emulsification and chilling These two mixtures are then emulsified in a vat with vigorous agitation. To prevent rapid separation of the emulsion, it must be quickly stiffened by chilling. This rapid cooling is achieved by pumping the emulsion through a series of heat exchangers, which may be equipped with special agitators to further subdivide the water droplets within the fat as it solidifies [67](#page=67). #### 4.3.3 Crystallization and plasticization Following emulsification, the emulsion is passed through chilled crystallizers. This step further solidifies and plasticizes the fat. Precise temperature control during this stage is vital for developing fat crystals of optimum size, which is essential for achieving the desired semi-plastic consistency. The Votator is a piece of equipment used to cool the mixture and produce margarine in a semi-solid state [68](#page=68) [70](#page=70). #### 4.3.4 Plastification and filling The semi-solid margarine is then plastified, ensuring its spreadability and texture. Subsequently, it is continuously extruded and packaged [68](#page=68). > **Tip:** The process flow for margarine production can be visualized as: Fat Base + Fat Soluble Ingredients → Water + Water Soluble Ingredients → Emulsification/cooling → Crystallization/stabilization → Plastification → Filling → MARGARINE [69](#page=69). #### 4.3.5 Packaging The final stage involves packaging the finished margarine product [68](#page=68). --- # Palm oil milling and refining This section details the crucial processes involved in transforming fresh fruit bunches into usable palm oil, emphasizing preservation principles and extraction methodologies [73](#page=73). ### 5.1 Principles of preservation in palm oil processing Effective preservation during palm oil processing is paramount to ensure a long shelf life and prevent deterioration. The core principles revolve around inhibiting microbial activity and slowing down chemical degradation. Key strategies include [80](#page=80): * **Sterilization:** The destruction of enzymes and contaminating microorganisms within the raw material is achieved through heat application during processing [80](#page=80). * **Dehydration:** Eliminating as much water as possible from the extracted oil is essential to prevent microbial growth, such as bacterial activity, thereby extending its shelf life [80](#page=80). * **Proper Packaging and Storage:** The final extracted oil must be packaged and stored appropriately to retard chemical deterioration, specifically rancidity [80](#page=80). ### 5.2 Extraction methods The extraction process aims to separate the oil from the palm fruit. While specific mechanical devices are mentioned, the general flow involves pressing and separation stages. #### 5.2.1 Screw press operation A screw press is a common piece of equipment used in palm oil extraction. The process typically involves [96](#page=96): * **Input:** The screw press receives the processed fruit or fruit material. * **Output:** It yields press oil, which is the crude oil, and press cake, a solid residue. Water is also an output of this stage [96](#page=96). * **Separation:** The press oil then moves to a screening tank for initial separation of solids [96](#page=96). * **Further Processing:** A decanter further separates the cleaned crude oil from solid byproducts. Foots (fines) may be recycled back into the process [96](#page=96). #### 5.2.2 Sterilization Sterilization is a critical step that precedes oil extraction. It involves applying heat to the fresh fruit bunches. This process serves to [90](#page=90): * Condition the fruit for easier oil release. * Inactivate lipase enzymes, which, if active, would rapidly hydrolyze triglycerides, leading to increased free fatty acids (FFAs) in the oil. * Loosen the fruit from the bunches, facilitating further processing. #### 5.2.3 Stripping Following sterilization, the fruit bunches are typically sent to a stripper. The stripper's function is to mechanically separate the sterilized fruits from the bunch structures (fronds and stems). This prepares the fruits for the subsequent stages of oil extraction [88](#page=88). ### 5.3 Refining of palm oil While the provided document content primarily focuses on the milling and extraction stages, the ultimate goal of these initial processes is to produce crude palm oil (CPO). CPO then undergoes refining to produce edible oils. Refining typically involves several steps designed to remove impurities, color, odor, and free fatty acids. These steps, though not detailed in the provided pages, are standard in the industry and would include: * **Degumming:** Removal of phospholipids and other gums. * **Neutralization:** Removal of free fatty acids (FFAs) using an alkali solution. * **Bleaching:** Removal of pigments (like carotenes) using bleaching earth. * **Deodorization:** Removal of volatile compounds that cause undesirable odors and flavors. ### 5.4 Unique characteristics of palm oil Palm oil possesses several unique characteristics that distinguish it from other vegetable oils. These properties are largely attributed to its fatty acid composition and triglyceride structure . * **Fatty Acid Profile:** Palm oil is unique in that it has a relatively balanced composition of saturated and unsaturated fatty acids. It is rich in palmitic acid (a saturated fatty acid) and oleic acid (an unsaturated fatty acid) . This balance contributes to its semi-solid state at room temperature and its stability . * **Fractionation:** Due to its composition, palm oil can be fractionated into different liquid (olein) and solid (stearin) fractions with distinct properties. This allows for its versatile application in various food products . * **Stability:** The presence of natural antioxidants, such as tocotrienols and tocopherols, contributes to palm oil's oxidative stability, making it less prone to rancidity compared to some other oils . * **Diglycerides:** The typical levels of diglycerides in refined palm oil are relatively low, often in the range of 2-6% . Diglycerides are formed during the esterification process and can affect the physical properties and stability of oils . > **Tip:** Understanding the principles of preservation, particularly sterilization and dehydration, is crucial for producing high-quality palm oil with a good shelf life. These steps prevent rapid degradation in the initial stages. > **Tip:** The ability to fractionate palm oil into liquid and solid components is a key advantage, enabling its use in a wide array of applications from cooking oil to margarines and shortenings. --- ## Common mistakes to avoid - Review all topics thoroughly before exams - Pay attention to formulas and key definitions - Practice with examples provided in each section - Don't memorize without understanding the underlying concepts

| Term | Definition | |------|------------| | Rendering | A process involving heating fatty animal tissues to melt the fat, allowing it to separate from the remaining solids and water. | | Lard | Fat obtained from hogs or pigs through the rendering process. | | Tallow | Fat obtained from beef through the rendering process. | | Dry Heat Rendering | A method of rendering where tissue is cooked under vacuum to remove moisture and extract fat. | | Wet Rendering | A method of rendering that uses hot water or steam to melt out fatty tissues and release fat. | | Pressing or Expelling | Mechanical methods used to extract oil from oilseeds by applying pressure, often after slight cooking or grinding to break cell structures. | | Solvent Extraction | A process that uses solvents to extract oil from oilseeds, achieving higher oil yields than mechanical pressing alone. | | Hexane | A common light petroleum hydrocarbon used as a solvent in solvent extraction due to its favorable boiling point and chemical properties. | | Percolation | A process where a solvent is passed through a material (like seeds) to extract soluble components, such as oil. | | Distillation | A process used to separate components of a liquid mixture by selective boiling and condensation, often employed to recover solvents. | | Refining | A broad term for processes that aim to remove non-triacylglycerol components, impurities, and undesirable characteristics from crude oils. | | Triacylglycerols (TAGs) | The primary form of fat in oils and fats, consisting of a glycerol backbone esterified with three fatty acids. | | Free Fatty Acids (FFAs) | Fatty acids that are not esterified to glycerol, often present in crude oils and removed during deacidification. | | Phosphoacylglycerols | A type of phospholipid found in oils that contains glycerol, fatty acids, and a phosphate group, often removed during degumming. | | Lecithin | A type of phospholipid, commonly derived from soybean oil, used as an emulsifier in the food industry. | | Degumming | A refining step focused on removing phosphatides and fat-protein complexes from crude oils, often by hydration with water. | | Deacidification (Alkali Neutralization) | A refining process where free fatty acids are neutralized with an alkali solution (like lye or NaOH) to form soaps, which are then removed. | | Bleaching or Decolorization | A refining step used to remove or reduce the color of oil, typically by adsorption onto materials like charcoal or adsorbent clay. | | Deodorization | The final refining step where volatile odoriferous compounds and residual free fatty acids are removed from the oil by stripping with steam under reduced pressure and elevated temperature. | | Hydrogenation | A fat modification process where hydrogen atoms are added to unsaturated fatty acids, saturating double bonds and making the fat firmer. | | Trans Fatty Acid | A type of unsaturated fatty acid with a double bond in a trans configuration, formed during hydrogenation, which can have adverse health effects. | | Fractionation | A fat modification process used to separate fats into fractions with different melting points, typically by controlled crystallization and filtration. | | Winterization | A type of fractionation specifically applied to oils to remove high-melting point glycerides that would cause cloudiness when chilled, ensuring clarity. | | Intraesterification | A fat modification process where the fatty acids and glycerol components within triacylglycerol molecules are rearranged and redistributed under catalyst influence to alter melting and crystallization characteristics. | | Margarine | A food product typically made from edible fats and oils, water, and other ingredients, formulated as a plastic emulsion or dispersion. | | Emulsifier | A substance that stabilizes an emulsion, preventing immiscible liquids (like oil and water) from separating. Lecithin is an example. | | Antioxidant | A substance that inhibits oxidation, helping to prevent rancidity and extend the shelf life of fats and oils. | | Sterilization (in Palm Oil Processing) | A process of heating raw palm material to destroy enzymes and contaminating microorganisms, preventing degradation and extending shelf life. | | Rancidity | The process of spoilage in fats and oils characterized by the development of unpleasant odors and flavors due to oxidation or hydrolysis. | | Diglycerides | Molecules composed of a glycerol backbone esterified with two fatty acids, often present as byproducts or intermediates in fat processing. | | Palm Stearin | A higher melting solid fraction derived from palm oil through fractionation. | | Palm Olein | A liquid fraction derived from palm oil through fractionation. | | RBD Palm Stearin | Refined, Bleached, and Deodorized Palm Stearin, a processed fraction of palm oil. | | RBD Palm Olein | Refined, Bleached, and Deodorized Palm Olein, a processed liquid fraction of palm oil. |