Soalan Lazim

Lemak kebanyakannya triesters asid lemak dan gliserol – dikenali sebagai trigliserida. Trigliserida yang terbentuk sebagai pepejal pada suhu bilik biasanya dipanggil lemak manakala yang cair dirujuk sebagai minyak. Lemak adalah nutrien penting yang menyediakan tubuh dengan tenaga dan juga bertindak sebagai sumber asid lemak. Cadangan pemakanan semasa adalah bahawa lemak diperlukan tidak lebih daripada 30% daripada keperluan tenaga seseorang. Dari segi nilai tenaga hasil lemak adalah 9 cal/g berbanding dengan 6 cal/g untuk kanji dan protein.

Apakah asid lemak tepu dan asid lemak tidak tepu?

Asid lemak tepu hanya mempunyai ikatan tunggal karbon (CC). Asid lemak yang sangat stabil. Contoh asid lemak tepu adalah asid palmitik, C16: 0 dan asid stearik, C18: 0. Asid lemak tidak tepu mengandungiikatan ganda dua karbon (C = C). Apabila hanya satu ikatan berganda hadir dalam rantaian karbon, asid lemak yang dipanggil mono tak tepu (contohnya, asid oleik, C18: 1). Apabila terdapat lebih daripada satugandaan-ikatan , maka asid lemak yang dipanggil tak tepu (contohnya, asid linoleik, C18: 2 dan asidlinolenik, C18: 3

Bagaimanakah kestabilan asid lemak tidak tepu?

Secara umumnya lebih tidak tepu asid lemak, ianya menjadi semakin tidak stabil. Kereaktifan kimia asid lemak poli tidak tepu juga bergantung kepada kedudukan ikatan ganda dua. Peningkatan kereaktifan ketara jika ikatan ganda dua adalah conjugated
(Dipisahkan oleh hanya satu ikatan tunggal) atau metilena-interupted (Dipisahkan oleh – unit CH2).

Bagaimanakah panjang rantaian karbon asid lemak mempengaruhi takat lebur minyak dan lemak?

Takat lebur asid lemak secara amnya meningkat dengan: –

• semakin panjang rantai
• peningkatan ketepuan
• perubahan cis-kepada trans-isomer

Oleh itu rantai pendek asid lemak tepu seperti asid butyric akan mempunyai takat lebur yang lebih rendah daripada rantaian panjang tepu asid lemak (contohnya, asid palmitik) dan juga beberapa panjang rantaian yang lebih tinggi asid lemak tidak tepu (contohnya, asid oleik). Ciri ini ditunjukkan apabila asid lemak membentuk sebahagian daripada trigliserida. Minyak yang lebih tepu atau lemak tidak semestinya mempunyai takat lebur yang lebih tinggi. Sebagai contoh, minyak kelapa yang merupakan kira-kira 87% tepu, tetapi mengandungi sebahagian besar daripada asid lemak rantaian pendek, mempunyai pelbagai julat lebur iaitu 24 ° C – 26 ° C, manakala minyak sawit iaitu kira-kira 49% tepu mempunyai takat lebur dalam julat 31 ° C – 38 ° C

Apakah cis dan trans-asid lemak?

Istilah cis dan trans menerangkan konfigurasi atom hidrogen yang disertakan dengan atom karbon dalam ikatan ganda dua minyak tidak tepu. Di dalam konfigurasi-cis, atom hidrogen ini terletak di sebelah yang sama yang mengandungi karbon untuk ikatan ganda dua karbon. Kebanyakan asid lemak semula jadi yang berlaku adalah isomer cis, tetapi kuantiti yang kecil asid lemak trans memang berlaku secara semula jadi di dalam lemak ruminan dan produk tenusu. Walau bagaimanapun, penghidrogenan separa akan menyebabkan pembentukan asid trans-lemak.

Apakah penyahbauan?

Penyahbauan adalah proses suhu tinggi di mana juzuk surih yang memberi rasa dan bau yang tidak diingini dikeluarkan dari lemak atau minyak. Proses ini pada asasnya melibatkan pembuangan komponen meruap oleh stim pada kira-kira 240-260 ° C di bawah vakum 2-5 mbars

Apakah pelunturan?

Pelunturan merujuk kepada proses di mana warna minyak dikurangkan dengan penyingkiran bahan-bahan penghasilan – iaitu pigmen. Pelunturan adalah sebahagian daripada proses penapisan dan melibatkan bahagian penghasilan bahan warna pada bahan penjerap dipanggil pemutihan bumi. Biasanya, pelunturan bumi tidak mengeluarkan semua bahan-bahan yang mengeluarkan warna, kebanyakannya dimusnahkan haba semasa proses penyahbauan itu.

Apakah penghidrogenan?

Penghidrogenan merupakan proses yang paling biasa digunakan untuk menukar minyak cecair ke dalam produk yang mempunyai ketekalan yang berbeza, takat lebur, dan tekstur. Ia adalah satu proses bermangkin di mana bilangan ikatan kembar dikurangkan dan pada masa yang sama pengisomeran asid lemak sisa digalakkan. Minyak cecair dengan trigliserida tidak tepu ditukar menjadi lemak yang mengandungi peratusan yang lebih tinggi ketepuan triglycerides. Sistem yang kompleks terdiri daripada tiga fasa; minyak cecair, gas hidrogen dan pemangkin pepejal (nikel yang paling banyak digunakan). Sebagai penghidrogenan berlangsung, terdapat peningkatan berperingkat dalam takat lebur minyak atau lemak. Apabila penghidrogenan penuh, di mana ikatan kembar dihapuskan sepenuhnya, produk ini adalah pepejal keras dan rapuh pada suhu bilik.

Kadar penghidrogenan keseluruhan bergantung kepada kualiti bahan tindak balas yang terlibat; tahap penapisan minyak yang akan hidrogenasi; aktiviti, tumpuan dan sifat pemangkin; tekanan hidrogen; suhu tindak balas; dan pengacauan .

Apakah pemeringkatan?

Pemeringkatan adalah proses yang digunakan untuk memisahkan lebih rendah trigliserida takat lebur daripada trigliserida takat lebur yang lebih tinggi. Proses ini adalah berdasarkan kepada perbezaan takat lebur pelbagai trigliserida dan melibatkan penghabluran yang membantu pengasingan pepejal daripada cecair. Terdapat pada asasnya tiga jenis pemeringkatan, iaitu pemeringkatan kering, detergen pemeringkatan dan pemeringkatan pelarut. Kesemuanya melibatkan secara beransur-ansur pengurangan suhu untuk mendorong penghabluran dan dengan itu pemisahan trigliserida takat lebur yang lebih tinggi (komponen pepejal – dipanggil stearin) dari yang lebih rendah trigliserida takat lebur (komponen cecair – dipanggil olein).

Apakah pemeringkatan kering?

Pemeringkatan kering adalah proses di mana pemisahan pepejal daripada bahagian cecair minyak yang dicapai melalui proses beransur-ansur penyejukan minyak yang dipanaskan. Prapemanasan (kepada kira-kira 70 ° C) dilakukan untuk memusnahkan mana-mana kristal ini. Pembentukan kristal berlaku sebagai minyak itu disejukkan menggunakan air sejuk yang berpusar di dalam jaket atau penyejukan gegelung. Apabila minyak yang mencapai suhu yang diingini, penyejukan dihentikan. Minyak yang dalam bentuk buburan kemudiannya ditapis untuk memisahkan stearin pepejal daripada olein cecair.

Apakah pemeringkatan detergen?

Proses ini melibatkan penghabluran minyak dan pemisahan pecahan dibantu oleh bahan pencuci (larutan natrium lauryl sulfat) dan elektrolit (magnesium sulfat). Elektrolit membantu dalam penumpuan terhadap pembetukan titisan minyak semasa proses pencampuran. Detergen membantu dalam pemeringkatan kerana ia membasahi kristal stearin dan mensesarkan olein yang tersumbat dan yang terperangkap. Ketumpatan olein yang rendah boleh dipisahkan daripada campuran stearin-detergen yang mempunyai ketumpatan yang lebih tinggi melalui proses emparan. Kesan detergen didalam olein boleh dikeluarkan melalui pembasuhan. Stearin yang lebih berat mengandungi kebanyakan bahan pencuci dipanaskan untuk mencairkan stearin dan kemudian disalurkan ke emparan kedua di mana stearin yang dipisahkan dari detergen. Bahan pencuci yang dipisahkan daripada stearin ini kemudian dikitar semula.

Apakah pemeringkatan pelarut?

Pemeringkatan pelarut adalah satu proses yang melibatkan penghabluran pecahan yang diingini daripada campuran trigliserida larut menggunakan pelarut yang sesuai. Pecahan tertentu boleh terhablur pada suhu yang berbeza selepas ianya dipisahkan dan pelarut dikeluarkan. Dua jenis pelarut yang biasa digunakan adalah heksana dan aseton. Penyejukan dilakukan dengan air sejuk, atau jika suhu yang sangat rendah diingini, air garam digunakan. Olein/stearin dipisahkan melalui proses penapisan.

Apakah interesterifikasi?

Interesterifikasi pada asasnya adalah satu proses yang melibatkan penyusunan semula atau pengagihan semula asid lemak yang melekat pada gliserol, sebahagian daripada molekul trigliserida. Penyusunan semula sama ada mengikut cara rawak atau terus – bergantung kepada keadaan pemprosesan. Reaksi terlibat umumnya jatuh ke dalam salah satu daripada kategori berikut:

• Acidolysis – reaksi ester lemak dengan asid – biasanya asid lemak
• Alkoholisis – tindak balas antara lemak dan alcohol
• Transesterifikasi – pertukaran radikal asid ester dari satu kepada yang lain

Apabila dilakukan dengan kehadiran pemangkin, Interesterifikasi boleh dilakukan pada suhu yang agak rendah berbanding jika ianya dijalankan tanpa pemangkin. Pemangkin yang paling biasa digunakan ialah natrium methylate dan ethylate, diikuti dengan logam natrium, sodium / aloi kalium dan natrium hidroksida dan kalium dalam kombinasi dengan gliserol.

Ya, terdapat perbezaan yang besar dalam ciri-ciri fizikal dan kimia mereka. Minyak dan lemak kebanyakannya terdiri daripada trigliserida dengan bahan-bahan bukan glyceridic dalam kuantiti yang kecil atau surih. Perbezaan komposisi kimia menerangkan keadaan kedua-dua serta perbezaan dalam ciri-ciri fizikal. Perbezaan antara kedua-dua minyak adalah seperti berikut:

Apakah komposisi lemak asid minyak sawit dan produk lain yang berkaitan?

Jadual di bawah menunjukkan komposisi biasa asid lemak yang terdapat dalam pelbagai produk minyak sawit di pasaran sekarang.

CPO: Minyak Sawit Mentah
CP Olein: Sawit Mentah Olein
CP stearin: Sawit Mentah stearin 

 Berikut adalah beberapa keperluan yang paling penting:

• Lebam minimum buah semasa penuaian, pengangkutan dan pergerakan di kilang.
• Masa yang minimum antara penuaian dan pensterilan
• Sistem pemprosesan mestilah memastikan buah atau minyak yang dikeluarkan tidak sejuk dan bersentuhan dengan alat atau bahan yang boleh menyebabkan permulaan semula lipolisis.

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

Keyword: processing

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:

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.

Keyword: refining

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.

Keyword: vanaspati 

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.

Keyword: density

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:-

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.

Keyword: lipids 

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: –

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.

• CarotenoidsCrude 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.
• Tocopherols/TocotrienolsCrude 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.
• SterolsThe 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 AlcoholsThese 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: –

(i) Sterilization

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.

(iii) Digestion

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.