An Edible or cooking oil is obtained from the fat of plant, animal or microbial origin, that exists in a liquid form at room temperature and is suitable for consumption.Edible oils are basically sources of dietary fats that play an essential role in the body, satisfying nutritional needs, growth and are necessary for proper functioning of the brain and nervous system as well as the endocrine system. Therefore, it is essential that we use completely refined and safe edible oils in our daily lives and get it regularly tested for any impurities.
People began the process of utilizing vegetable oils centuries ago. In the very beginning, they obtained oil by heating animal fats and by pressing various plants, seeds, and nuts. These oils were not processed or refined like the ones we use today. As time went by and technology advanced, the ingredients used to extract oil were treated differently and refining oils has become easier than ever.
Around 2000 BC, the Japanese and Chinese crested soy oil. Even today, soy oil is one of these countries' most utilized vegetable oils. Whereas the Europeans in the southern part of the continent are believed to have started producing olive oil since 4000 BC.
Indians have broadly used two types of edible oils. The first was ‘vegetable’ oil obtained from crushing local oilseeds like mustard in northern and eastern India; groundnut in Gujarat, Maharashtra, Karnataka and Andhra Pradesh; sesame and groundnut in Tamil Nadu; and coconut in Kerala. The second type of cooking oil was ‘animal’ fat, mainly desi-ghee prepared from milk.
The first major market revolution came in 1937 when Hindustan Unilever launched ‘Dalda’. This was essentially vanaspati or hydrogenated vegetable oil. Hydrogenation means adding hydrogen to convert unsaturated liquid fats into saturated solid. The purpose behind this was to harden and raise the melting point of the oil, which yielded a product mimicking desi-ghee.
The higher melting point (at which the molecules start breaking down) made vanaspati better suited for deep frying than normal vegetable oils. Cooking in vanaspati also extended the shelflife of food, which was a huge deal when only a few homes could afford refrigerators.
There are two different kinds of sources for extraction of edible oils. They can be categorized into vegetable and animal/marine origins.
The sources of Animal fats/ Animal based oils are:
The sources of Vegetable oils are:
Extraction Process can remove the components of edible oils which may have negative effects on taste, stability, appearance or nutritional value.
The following are the various different types of oil extraction:
1) Hot water extraction
In oil extraction, milled seed is mixed with hot water and boiled to allow the oil to float and be skimmed off. The milled oil seed is mixed with hot water to make a paste for kneading by hand or machine until the oil separates as an emulsion. In groundnut oil extraction, salt is usually added to coagulate the protein and enhance oil separation.
2) Mechanical expeller extractors
A large rotating pestle in a fixed mortar system can be powered by motor, humans or animals to apply friction and pressure to the oil seeds to release oil at the base of the mortar. Other traditional systems used in rural oil extraction include the use of heavy stones, wedges, levers and twisted ropes.
For pressing, a plate or piston is manually forced into a perforated cylinder containing the milled or pulped oil mass by means of a worm. The oil is collected below the perforated chamber. The pre-heated raw material is fed into a horizontal cylinder by a worm shaft. By means of an adjustable choke, internal pressure which is built up in the cylinder ruptures the oil cells to release the oil.
3) Press-pressed cakes
A by-product of processing, the pressed cake, may be useful depending on the oil extraction technique applied. Cakes from water-extracted oil are usually depleted of nutrients. Other traditional techniques, for instance, those used for groundnut and copra ensure that the by-products, if handled with care, are suitable for human consumption.
4) Industrial or commercial-scale production
Processing: Oilseeds are generally cleaned of foreign matter before dehulling. The kernels are ground to reduce size and cooked with steam, and the oil is extracted in a screw or hydraulic press. Oil can be directly extracted with solvent from products which are low in oil content, that is, soybean, rice bran and corn germ.
After sterilization, oil-bearing fruits are pulped before mechanical pressing, often in a screw press. Palm kernels are removed from pressed cakes and further processed for oil. Animal tissues are reduced in size before rendering by wet or dry processes. After autoclaving, tissues of fish are pressed and the oil/water suspension is passed through centrifuges to separate the oil.
Sometimes the Oil quality deteriorates by hydrolysis, oxidation and polymerization of the oil. Therefore, monitoring and maintaining edible oil quality are of paramount importance to ensure safety of the product for consumption. The official standard set for evaluating edible oil quality, FFA content, peroxide value (PV) and p-anisidine value (AV) are commonly used in industry to report edible oil quality.
There have been incidents of oil adulteration where groundnut oils contained undeclared less quantities of cheaper oils like soybean oil. Likewise, cottonseed oil adulterated with palmolein oil. Detection of these adulterations is of utmost importance.
We understand edible oils present analytical challenges due to their chemical complexity. That is why, we utilize easy-to-use methods to analyze oils for nutrition, contamination and composition, as well as adulteration and authenticity. The various tests we conduct are:
Atlas Lab’s lube oils are tested as per international standards like ASTM, IS and JASCO. Atlas Lab is your best go-to place for the most precise testing solutions.
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