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Keyword : fats, oils
Fats are predominantly triesters of fatty acids and glycerol – commonly known as triglycerides. Triglycerides that appear as solid at room temperature are normally called fats while those that are liquid are referred to as oils. Fat is a vital nutrient that provides the body with energy as well as acts as a source of essential fatty acids. Current dietary recommendations are that fats should supply no more than 30% of a person’s energy requirement. In terms of energy value a gram of fat yields 9 cal of energy compared to 6 cal/g for starch and proteins.
Keyword : saturated, unsaturated, fatty acid
Saturated fatty acids are those which have only single carbon-to-carbon bonds ( C-C ). These fatty acids are very stable. Examples of saturated fatty acids are palmitic acid, C16:0 and stearic acid, C18:0. Unsaturated fatty acids contain carbon-to-carbon double bonds ( C=C ). When only one double bond is present in the carbon chain, the fatty acid is called monounsaturated ( e.g. oleic acid, C18:1 ). When there are more than one double-bond, then the fatty acid is called polyunsaturated ( e.g. linoleic acid, C18:2 and linolenic acid, C18:3 )
Keyword : stable, unsaturated
Generally the more unsaturated the fatty acid, the more unstable it will be. The chemical reactivity of polyunsaturated fatty acid also depends on the positions of the double bonds. Reactivity increases substantially if the double bonds are conjugated
( separated by only one single bond ) or methylene-interupted
( separated by a – CH2 unit )
Keyword : chain length, melting point
The melting points of fatty acids generally increase with:-
increasing chain length
changing of a cis-to a trans-isomer
Thus a short chain saturated fatty acid such as butyric acid will have a lower melting point than long chain saturated fatty acids
( e.g. palmitic acid ) and even some higher chain length unsaturated fatty acids ( e.g. oleic acid ). This property is reflected when the fatty acids form part of a triglyceride. The more saturated oil or fat may not necessarily have a higher melting point. For example, coconut oil which is about 87% saturated, but contains a high proportion of short chain fatty acids, has a melting range of 24°C – 26°C while palm oil which is about 49% saturated has a melting point in the range of 31°C – 38°C.
Keyword : cis, trans
The term cis and trans describe the configuration of the hydrogen atoms attached to the carbon atoms in double bonds of unsaturated oils. In the cis-configuration, these hydrogen atoms are located on the same side of the plane containing the carbon to carbon double bonds. Most naturally occurring fatty acids are cis isomers, but small quantities of trans fatty acids do occur naturally in ruminant fats and dairy products. However, partial hydrogenation will cause the formation of trans-fatty acids.
Keyword : deodorization
Deodorization is the high temperature process in which trace constituents which give undesirable flavours and odors are removed from fat or oil. The process essentially involves the removal of these volatile components by steam at about 240-260°C under a vacuum of 2-5 mbars.
Keyword : bleaching, colour
The term bleaching refers to the process in which the colour of the oil is reduced by removal of the colour producing substances – i.e. pigments. Bleaching is part of the refining process and involves in part the adsorption of colour producing materials on an adsorbent material called bleaching earth. Usually, bleaching earth does not remove all the colour producing materials, much of which are actually removed by thermal destruction during the deodorization process.
Keyword : hydrogenation
Hydrogenation is the process most commonly used to convert liquid oils into products which have different consistencies, melting points, and textures. It is a catalytic process in which the number of double bonds are reduced and at the same time, isomerization of residual fatty acids promoted. Liquid oils with unsaturated triglycerides are transformed into fats containing a higher percentage of saturated triglycerides.The complex system consists of three phases; liquid oil, gaseous hydrogen and solid catalyst ( the most widely used is nickel ). As hydrogenation progresses, there is a gradual increase in the melting point of the oil or fat. Upon full hydrogenation, whereby the double bonds are eliminated entirely, the product is a hard brittle solid at room temperature.
The overall hydrogenation rate depends on the quality of the reactant involved; the degree of refining of the oil to be hydrogenated; the activity, concentration and nature of the catalyst; hydrogen pressure; reaction temperature; and stirring.
What is fractionation?
Fractionation is the process used to separate the lower melting point triglycerides from the higher melting point triglycerides. The process is based on the difference of melting points of the various triglycerides and involves crystallization which helps separate the solids from liquids. There are essentially three types of fractionation, i.e. dry fractionation, detergent fractionation and solvent fractionation. All three involve the gradual lowering of temperature to induce crystallization and hence separation of higher melting point triglycerides ( solid component – called stearin ) from the lower melting point triglycerides ( liquid component – called olein ).
Keyword : dry fractionation
Dry fractionation is the process in which separation of the solid from liquid portion of the oil is achieved by a process of gradual cooling a preheated oil. The preheating ( to about 70°C ) is done to destroy any crystal present. Crystal formation and growth occurs as the oil is agitated and cooled using chilled water circulating in the jackets or cooling coils of the crystallizers. When the oil reaches the desired temperature, the cooling is stopped. The oil which is in the form of slurry is then filtered to separate the solid stearin from liquid olein.
Keyword : detergent fractionation
The process involves crystallization of the oil and separation of fractions aided by a detergent ( sodium lauryl sulphate solution ) and an electrolyte ( magnesium sulphate ). The electrolyte helps in agglomeration of oil droplets formed during the mixing process. The detergent helps in fractionation as it wets the stearin crystals and displaces occluded and entrained olein. The lower density olein can be separated from the stearin-detergent mixture of higher density by centrifuging. The traces of detergent in olein can be removed by washing. The heavier stearin phase containing most of the detergent is heated to melt the stearin and then sent to a second centrifuge where the stearin is separated from the detergent. The detergent separated from the stearin is then recycled.
Keyword : solvent fractionation
Solvent fractionation is a process involving the crystallization of a desired fraction from a mixture of triglycerides dissolved in a suitable solvent. Fractions may be selectively crystallized at different temperatures after which they are separated and the solvent removed. The two common solvents used are hexane and acetone. Cooling is done by chilled water, or if very low temperatures are desired, brine. The olein/stearin fractions are separated by a process of filtration.
Keyword : interesterification
Interesterification is essentially is a process which involves the rearrangement or redistribution of fatty acids attached to the glycerol part of the triglyceride molecule. The rearrangement can be either in random or direct manner – depending on the processing conditions. The reaction involved generally falls into one of the following categories:
Acidolysis – reaction of fatty ester with an acid – usually a fatty acid
Alcoholysis – reaction between fat and alcohol
Transesterification – exchange of acid radicals from one ester to another
When carried out in the presence of catalysts, interesterification can be done at relatively low temperatures than when it is carried out without catalysts. The most commonly used catalysts are sodium methylate and ethylate, followed by sodium metal, sodium/potassium alloy and the hydroxide of sodium and potassium in combination with glycerol.
Keyword : physical, chemical properties
Yes, there are great differences in their physical and chemical properties. Oils and fats are made up mostly of triglycerides with some non-glyceridic materials in small or trace quantities. Difference in chemical composition reflect themselves in differences in physical properties as well. The differences between the two oil are as follows :
Palm Oil (PO)
Palm Kernel Oil (PKO)
PO consists mainly of palmitic acid C16:0 (43.7%), stearic acid C18:0 (4.4%), oleic acid C18:1 (39.9%) and linoleic acid C18:2 (10.3%)
PKO closely resembles coconut oil in its fatty acid (FA) composition. It has a higher content of shorter chain FA, lauric acid C12:0 (48%) and myristic acid C14:0 (16%) approx.
|Minor components||Minor components|
Carotenoids: 500-700 ppm
Tocopherols/ tocotrienols: 600-1000 ppm
Carotenoids: very low levels
Tocopherols/ tocotrienols: Tocopherols level similar to PO but only traces of tocotrienols
Average: 18 ppm
Palm oil has very low levels of cholesterol as similar to other vegetable oils. The value is even lower in RBD PO
Average: 17 ppm
Palm oil can be separated by physical processes into 2 fractions, i.e. solid (stearin) and liquid (olein)
In temperate climates, PKO is a sharp melting fat very suitable for confectionery and similar uses. PK stearin has physical properties very similar to cocoa butter and makes the best Cocoa Butter Substitute (CBS)
Keyword : fatty acid composition
The table below gives the typical fatty acid composition of various palm oil products available in the market now.
CPO : Crude Palm Oil
CP Olein : Crude Palm Olein
CP Stearin : Crude Palm Stearin
Keyword : low free fatty acid , processing
The following are some of the most important requirements.
Minimal bruising of the fruit during harvesting, carriage and movement at the mill side.
Minimal time lapse between harvesting and sterilization
The processing system must be such that the fruit or extracted oil do not cool down and come into contact with apparatus or material which could cause a recommencement of lipolysis.
Keyword : superolein
Fractionation of palm oil yields olein (liquid) and stearin (solid) fractions. Further fractionation of the olein component yields double-fractionated olein and palm mid-fraction (PMF). The olein thus obtained is usually called superolein as it has a high Iodine Value (IV) and therefore has a lower cloud point.
At present, there is no international standard for superolein. Individual countries, therefore, many have their own standards.
Malaysian superolein (or double fractionated palm olein) is traded under the PORAM standards which are as follows:-
Free Fatty Acid (FFA) 0.1% max
Moisture & Impurities (M+I) 0.1% max
Iodine Value (IV) 60 min
Slip Melting Point (SMP)19 °max
Colour (5 1/4 ” Lovibond) 3 Red max
Crude Palm Oil (CPO) in Malaysia is normally refined, bleached and deodorized by physical means to give Refined, Bleached Deodorized Palm Oil (RBD PO). A much smaller quantity is neutralized chemically (with sodium hydroxide solution) and then bleached and deodorized to give Neutralized Bleached, Deodorized Palm Oil (NBD PO), which some people prefer for certain specialized uses.
The physical process gives a by-product of high Free Fatty Acid (FFA) called Palm Fatty Acid Distillate (PFAD) and the chemical process gives the byproduct called palm acid oil (PAO) with a somewhat lower acidity than PFAD.
Palm Oil is a soft plastic fat of medium melting point (m.pt.) (33-39° C). In order to expand the range of its uses, very large quantities are fractionated by physical means to give a liquid or semi-liquid fraction (m.pt. 24° C max) called olein and a much harder fraction (m.pt.44° C min) called stearin.
Increasing quantities of standard olein are fractionated again to give double fractionated olein which remains liquid at lower temperatures (m.pt. 19° C max).This process also produces Palm Mid Fraction (PMF) which is used in all true Cocoa Butter Equivalents (CBEs) made in the West.
Keyword: vitamin e, nutrition
Heart disease remains the biggest cause of death (especially in the Western countries) and it increases with age. Even in the developing countries, heart disease is on the increase and rising towards the level found in the developed countries.
A team of medical scientist at Cambridge University studied the effect of vitamin E supplements on the health of 2000 patients who had suffered a previous heart attack. They found that regular high doses of vitamin E of over 400 IU per day reduced the risk of a second heart attack by 75%.
At present, the main source of vitamin E is the deodorizer distillate from soyabean oil refining but the oil palm is by far the largest potential source. CPO contains 0.08% tocopherols and tocotrienols. Palm Fatty Acid Distillate (PFAD), 0.4%, and palm leaflets 0.5% (dry basis). It can be calculated that the amount of vitamin E which could be theoretically produced in Malaysia as follows:
From Oil Palm Leaflets (Tonnes)
From PFAD (Tonnes)
If the vitamin E from oil palm leaflets and PFAD sources were fully exploited, it would be enough to meet the daily requirements of the whole world population in the year 2000.
The above objectives are achieved by the refining process. In the physical refining process which is used in Malaysia for palm oil, the oil is first bleached with activated clay and then subjected to steam distillation under high vacuum. This process removes the free fatty acids and the odouriferous compounds and further bleaches the oil to a pale yellow or white colour when set.
Keyword : bleaching earth
The use of activated bleaching earth (clay) in the processing of oils and fats has a long and successful history.
Bleaching earths have gradually and steadily improved in quality so that with reasonably good crude palm oil, addition of about 1% enables the desired final colour limit of 3 RED (5.25 inch Lovibond cell) to be reached every time.
But the performance of a bleaching earth cannot be assessed on colour considerations alone because the removal of phosphatides and trace metals is also very important in ensuring maximum stability to oxidation and resistance to flavour deterioration.
Now new materials are challenging the position of bleaching earth e.g. the development of silica hydrogel which, when used to replace part of the bleaching earth, lead to equally good colour values in the finished oil, and also much better removal of phosphatides.
Thus, 0.3% hydrogel plus 0.6% bleaching earth gives better removal of trace metals and gums than 1.3% bleaching earth alone.
Vanaspati is a homogenous blend of edible vegetable oils such as cottonseed oil, soybean oil, palm oil, rice-bran oil, maize oil and mahua oil, which are refined to remove impurities and colour, deodorized to remove odour in oils and hydrogenated to form a nutritious and pure cooking fat.
Only vegetable oils are permitted in vanaspati.
Vanaspati is a cooking fat originally developed as an alternative to the traditional butter fat ghee. Vanaspati is semi solid and has a coarse granular structure at ambient temperature with crystals 1-2 mm in size, but is usually required to have a melting point of 37°C – 39° C. To the housewives, vanaspati offers distinct advantages. Food cooked in vanaspati has no characteristic flavour of edible oils. It has longer shelf-life and therefore, can be kept for a longer period. Some sweets and confectionery items of daily use which require a hard fat can only be made with vanaspati and not with liquid oils or ghee. Originally vanaspati was made from hydrogenated vegetable oils but hydrogenation is a fairly costly process and produces undesirable trans fatty acids.
Palm oil has similar physical characteristics to vanaspati such as melting point of about 36°C and semi-solid consistency at ambient temperature, and although it does not naturally develop the desired granular appearance, this can be improved by interesterification.
Formulations based on interesterified blends of palm oil and its products (especially palm stearin) with a variety of other vegetable oils have been tested by PORIM with good results. All the tested samples were similar to the conventional hydrogenated vanaspati with respect to melting characteristics and physical appearance, including granulation and phase separation but most important, they were free of trans fattty acids.
The main reasons are non-homogenity of the oil in storage , themometer calibration and other experimental errors.
Heating alone, even though at recommended storage temperatures, may not be enough to ensure a completely homogenous and representative sample, especially in large storage tanks. This inevitably leads to inaccuracies in density determination.
The use of stirrers or agitators in combination with heating helps to produce a more homogenous liquid and more uniform temperature readings. Care should be taken never to allow oils to cool below recommended storage temperatures such that heating becomes ineffective in producing a homogenous liquid.
Keyword: fatty acids, cooking oils
The most common fatty acids in commercial cooking oils are the palmitic, stearic, oleic and linoleic acids. The range is very wide depending on the oil, but for Malaysian palm oil it is as follows:-
0.7 – 1.0
36.7 – 39.4
3.6 – 4.4
43.6 – 45.3
10.8 – 12.1
Keyword: trans free
Foods products are said to be trans free if they contain no significant levels of trans fatty acids. They are formulated without the use of hydrogenated oils or animal fats which always contain some trans fatty acid.
Some nutritional studies have shown that dietary trans fatty acids have adverse effects on health e.g. they have been shown to reduce the level of the beneficial HDL-cholesterol, and raise the level of the atherogenic LDL-cholesterol, so altering the LDL/HDL-cholesterol ratio detrimentally. These changes increase the risk of heart disease.
Trans fatty acids also increase the level of lipoprotein Lp@, which is an independent and powerful risk factor for heart disease.Several other studies have implicated trans fatty acids in increasing the risk of cancer, interfering with fat metabolism and reducing the body’s ability to rid itself of carcinogens, drugs and other toxins.Thus it is not surprising that many products use palm oil as natural source of trans free fatty acids.
The term “lipids” embraces a variety of chemical substances. In addition to triglycerides, lipids also include mono- and diglycerides, phosphatides, cerebosides, sterols, terpenes, fatty alcohols, fatty acids, fat-soluble vitamins and other substances.
Keyword: vegetable oils
Vegetable oils are those oils that are derived from plant sources. Palm oil, corn oil, soybean oil, cottonseed oil, coconut oil and palm oil are all examples of vegetable oils.
Keyword: fatty acids, classification, saturated,unsaturated, monounsaturated, polyunsaturated, double bonds
Fatty acids naturally occurring in edible fats and oils are classified according to their degree of saturation: –
Saturated Fatty Acids Fatty acids containing only single carbon-to-carbon bonds are termed “saturated” and are the least reactive chemically. The melting point of saturated fatty acids increases with chain length. Decanoic and longer chain acids are solids at normal room temperatures.
Unsaturated Fatty Acids Unsaturated fatty acids containing one or more carbon-carbon double bonds are termed “unsaturated”. When the fatty acid contains one double bond it is called “monounsaturated” or “monoenoic”. If it contains more than one double bond, it is called “polyunsaturated” or “polyenoic”.
keyword: polyunsaturated fatty acids, PUFA,linoleic acid, linolenic acid
These are fatty acids having two or more double bonds in their carbon chain. The most common polyunsaturated fatty acids are linoleic acid (C18: 2) and linolenic acid (C18:3). Corn oil, sunflower oil and soybean oil are examples of vegetable oils rich in polyunsaturated fatty acids. Palm oil contains about 10% linoleic acid and about 0.5% linolenic acid.
Keyword: palm oil, palm kernel oil, composition
Palm oil is derived from the mesocarp of the palm fruit, while palm kernel oil is derived from the kernel of the fruit. The chemical characteristics of the two oils differ in terms of the fatty acid composition. Differences in chemical composition reflect themselves in differences in physical properties as well. The main differences in the chemical composition of the two oils are as follows: –
|Palm Oil||Palm Kernel Oil|
|Consists mainly of palmitic acid C16:0 43.7%, stearic acid C18:0 4.4%, oleic acid C18:1 39.9%, and linoleic acid 10.3%||Consists mainly of lauric acid C12:0 48%, and myristic acid C14:0 16%|
Keyword: palm oil, coconut oil, fatty acids
Palm oil is composed of about 44% palmitic acid (C16: 0), 40% oleic acid (C18: 1) and 10% linoleic acid (C18: 2). Palm oil is thus a balanced oil as it contains roughly equal amounts of saturated and unsaturated fatty acids.
Coconut oil however contains about 87% saturated fatty acids in the form of 44.6% lauric acid (C12: 0), 16.8% myristic acid (C14: 0), 8.2% palmitic acid (C16: 0), 7.5% caprylic acid (C8: 0), 6.0% capric acid (C10: 0). The unsaturated fatty acids in coconut oil are 5.8% oleic acid (C18: 1) and 1.8% linoleic acid (C18: 2).
Though palmitic acid, the predominant fatty acid in palm oil is a saturated fatty acid, it has been found to be less hypercholesterolemic than shorter chain saturated fatty acids.
Keyword: Minor components, crude palm oil,carotenoids, carotenes, tocopherols, tocotrienols, sterols, cholesterol,phosphatides
The minor components in crude palm oil are carotenoids, tocopherols, sterols, phosphatides, triterphenic and aliphatic alcohols. Though these minor components represent less than 1% of palm oil composition, they play a significant role in the stability and refinability of the oil, in addition to increasing its nutritive value.
Crude palm oil contains 500-700 ppm carotenoids, mainly as alpha- and beta-carotenes, the precursors of Vitamin A. Carotenoids are usually thermally destroyed during the deodorization stage of the refining process. Their presence however, offers some oxidative protection to the oil by themselves being oxidised first prior to the triglycerides.
Crude palm oil contains 600-1000 ppm tocopherols and tocotrienols. These levels are slightly lower in refined palm oil. The major forms of tocopherols and tocotrienols present in palm oil are alpha-tocopherol and gamma-tocotrienols. Tocopherols and tocotrienols are antioxidants and provide some natural oxidative protection to the oil.
The sterols in crude palm oil are in the form of sitosterol (218-370ppm), campesterol (90-151 ppm), stigmasterol (44-66 ppm), cholesterol (7-13 ppm) and others (2-18 ppm). Upon refining, their levels are reduced to 68-114 ppm, 26-30 ppm, 12-23 ppm and 2 ppm respectively. It must be emphasised that the cholesterol levels in both crude and refined palm oil are lower than levels in most vegetable oils.
Phospholipids and Triterpene Alcohols
These components are present in extremely minute amounts in crude palm oil. The main forms of phospholipids are phosph- a tidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylglycerol. The triterpene alcohols are present in the form of cycloartanol, beta-Amyrin, cycloartenol and 2,4-Methylene cycloartanol.
Keyword: processing, fresh fruit bunch (FFB), milling, sterilization, clarification, purification, digestion
The main stages of processing FFBs are: –
Fruit bunches are sterilized by steam at about 140°C for a period of 75-90 minutes. The main objectives are to deactivate hydrolytic enzymes responsible for the breakdown of oil to free fatty acids; to loosen the fruits from bunches; to coagulate mucilage to facilitate breaking of oil cells and aid recovery of oil; and precondition nuts to minimize kernel breakage.
(ii) Bunch Stripping
The fruits are stripped and separated from the bunch in a rotary drum stripper. Fruits are knocked out of the bunch by the lifting and dropping of bunches as they pass through the stripper. The detached fruits fall through the spaces between the bars on the stripper and are collected in a conveyor, which then feeds them into the digester.
Digestion involves the mashing up of the fruits under steam heated conditions. The digester is a vertical cylindrical vessel fitted with a rotating staff carrying a number of stirring arms. The action of the stirring arms breaks up the oil-bearing cells of the mesocarp to form a digested mash.
(iv) Oil Extraction
Twin screw presses are generally used to press out the oil from the digested mash. Hot water may be added to enhance the oil flow and the crude oil slurry is collected in the crude oil tank for purification. The fibre and nut (press cake) are conveyed to depericarper for separation.
(v) Clarification and Purification
The crude palm oil (CPO) mixture from the screw press consists of a mixture of crude oil (35-45%), water (45-55%) and fibrous materials and other solids in varying proportions. The mixture is pumped into a continuous clarification tank. The oil is maintained at about 90°C to enhance oil separation. The oil is continuously skimmed off the top of the tank while the denser impurities settle at the tank bottom. The oil is passed through a high-speed centrifuge and a vacuum dryer to a moisture content of below 0.1% before being sent to the storage tank.
Keyword: DOBI, bleachability, crude palm oil
The Deterioration of Bleachability Index (DOBI) is a ratio of the uncorrected absorbance values at 446 nm to that of at 269 nm. It is an indication of the bleachability of the crude palm oil based on the amount of carotenes still present in the crude oil and the amount of secondary oxidation products. A good easily bleached crude palm oil will have a DOBI of 4, while average quality crude will exhibit a DOBI of 2.5 to 3.
Keyword: degumming,phosphatides, gums, bleaching
Fats and oils contain complex organo-phosphorus compounds referred to as phosphatides or more usually, as gums. They are removed during processing by a variety of treatments collectively referred to as degumming. The treatment usually involves hydration with water, orthophosphoric acid, and polybasic organic acids either singly or in combination, followed by centrifuging the precipitated material or by its adsorption on bleaching earth or filter.
Keyword: palm kernel, palm kernel cake, palm kernel oil
Palm kernels produced during the milling process of palm fruits contain approximately 50% oil that can be extracted commercially via two methods, i.e. mechanical expression and solvent extraction. Palm kernel cake is the by-product of the oil extraction process. The main use of this product is as an ingredient for compounding animal feed. It has high fibre content and thus is usually used in foods for ruminants such as cattle. However palm kernel cake is also a good source of phytin, which is a precursor of phytic acid and inositol. The latter compounds have many industrial applications. PORIM has patented the extraction process for phytin and is working closely with the local industry to develop further into this new area.
Keyword: refining, chemical, physical
The aim of refining process is to reduce the free fatty acid content and to remove other gross impurities such as phosphatides, proteinaceous and mucilagenous substances present in crude oils. The process is normally carried out on vegetable oils as animal fats, are usually not refined. The most common method of refining is by treatment of the fat or oil with an alkali solution, i.e. chemical refining. This results in a large reduction of free fatty acids through their conversion into water-soluble soaps. Phosphatides, proteinaceous and mucilagenous substances are soluble in the oil only in an anhydrous form and upon hydration with the caustic or other refining solution are readily separated. Oils low in phosphatide content such as palm and coconut oils, on the other may undergo physical refining, i.e. by the use of stripping steam to distil off the more volatile impurities.
Keyword: acid oil, soap
During alkali refining, free fatty acids are neutralised by the alkali (sodium hydroxide) forming soap stock. This soap stock containing some emulsified neutral oil is separated and acidified with concentrated sulphuric acid to produce oil, which is mainly fatty acid. Acid oil requires further refining or purification before it is used in laundry soap and washing powder.
Keyword: citric acid, chelating agent, oxidative properties
Citric acid is added to oils and fats to improve their oxidative properties. Citric acid acts as chelating agent that deactivates the catalytic activities of pro-oxidant metals such as copper and iron.
Keyword: antioxidant, handling, transportation, citric acid,oxidation
Citric acid and other anti-oxidants are best-added on-line at the cooling stage after deodorization i.e. at temperatures of 120ºC or lower. It is important to ensure complete dispersion and dissolution of antioxidants in the oil by the incorporation of a static mixer in the line. Citric acid is of course acidic, and therefore if it is not properly mixed, the build-up of localized concentrations could be detrimental to the tank coatings or to mild steel tank walls.
Keyword: pressing, fractionation
“Pressing” is sometimes used during the fractionation process to separate small amounts of liquid oil from a larger quantity of solid fat. The process squeezes or presses the liquid oil from the solid fat by means of hydraulic pressure. This process is used commercially to produce hard butters from fats such as palm kernel oil and coconut oil.
Keyword: winterization, clouding, crystallized
Winterization is a process whereby a small quantity of higher melting triglycerides is crystallized and removed from edible oils by filtration to avoid clouding of the liquid fractions at refrigeration temperatures. Originally, this processing was applied to cottonseed oil by subjecting the oil to ambient winter temperatures, hence the term “winterization”. Today, cottonseed oil is chilled using refrigeration and the practice has been extended to other vegetable oils.