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.

How did Edible Oils come into existence?

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.

What are the different sources of Edible Oil and its types?

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:

• Butterfat
  This is usually obtained from cow's milk. It is a mixture of fat, water and salt. Butterfat is an important source of vitamin A and to a lesser extent of vitamin D. Its distinct flavor and yellow color play an important factor in its popularity. It is mainly used as a common bread spread. Butterfat is a part of many other dairy products such as milk, cheese, ice cream, coffee cream and whipping cream.


• Lard
  Lard is a fat rendered from the fatty tissues of a pig. Lard is just as versatile as any other cooking fat and can be used for roasting, grilling, sauteing, frying and baking. In its solid form it can be used just as butter or seasoning and can be added to baking recipes. It can also be used on a cast-iron skillet pan for all kinds of frying.


• Tallow
  Edible tallow is obtained primarily from beef and cattle. At room temperature, it is harder and firmer than lard.


• Fish oils
  Fish oils can be obtained from the bodies or livers of several fish including cod fish, whale, salmon etc. Fatty acid composition varies not only from species to species, but often from one fish to another of the same species.


• Cod liver oil
  This is derived from the liver of cod fish. As with most fish oils, it has high levels of the omega-3 fatty acids. Cod liver oil also contains vitamin A and vitamin D.

The sources of Vegetable oils are:

• Soybean oil: This is obtained from the seed of the soybean plant. This is the oil produced that is produced in the largest quantity. About 48% of soybean oil is used in margarine, shortening, cooking, salad oils, and mayonnaise.


• Canola oil: This edible oil is obtained from a relatively new variety of rape seed plant. It occupies the third position in order of production of oils and fats. Canola oil has a low level of saturated fatty acids (about 6%) making it the second most important source of vegetable oil.


• Sunflower oil: It is the fourth of the most popular vegetable oils and in some countries; it is preferred to soybean, cotton seed and palm oils but it is grown in limited geographical locations.


• Coconut oil: This is obtained from copra, which is dried coconut meat from the coconut palm tree. It is characterized by a high percentage of liquid acid. It has a tendency to cause a foaming problem due to its very low molecular weight; therefore does not mix comfortably with other oils.


• Palm kernel oil: This is also known as lauric oil and stands second to coconut oil in the international market. The fatty acid composition and properties of palm kernel oil are very similar to those of coconut oil, but it has a little lower, shorter chain fatty acids and higher insaturation.


• Groundnut (peanut) oil: Groundnut oil is pressed from peanut, earthnut, and groundnut. Groundnut oil has a high content of digestible protein and is unsaturated with a roasted nutty flavor. The crude oil is pale yellow and is primarily used as a cooking oil.


• Olive oil: Virgin olive oil is obtained from the fruits of the olive tree. Virgin olive oil is oil that has not been deodorized to remove natural olive oil flavor elements which are considered to be desirable by the consumers.


• Sesame seed oil: This is obtained from sesame seed, which has high oil content. It is highly resistant to oxidation and displays several medicinal effects. Compared with other vegetable oil, sesame oil is highly resistant to oxidative deterioration.


• Flaxseed (linseed) oil: This is obtained from the linseed plant. It imparts a paint-like flavor to food products in a very short time therefore edible flaxseed oil is stored under cold, oxygen free, light free conditions and is protected by addition of an antioxidant. It is sold at many health and food stores.


• Mustard oil: : This is obtained from the linseed plant. It imparts a paint-like flavor to food products in a very short time therefore edible flaxseed oil is stored under cold, oxygen free, light free conditions and is protected by addition of an antioxidant. It is sold at many health and food stores.

What are the techniques employed for the extraction of Edible Oils?

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.

Why does testing of Edible Oil play an important role in our daily lives?

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.

How does Atlas Lab make a difference in the testing of Edible Oils?

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:

• Full Test as per FSSAI / PFA / BIS


• Gas Liquid Chromatography (GLC) for estimation of Fatty Acids, Saturated and Unsaturated Fatty Acids, Monounsaturated Fatty Acids, Polyunsaturated Fatty Acids, Trans Fatty Acids, Omega – 3, 6 & 9.


• Shelf Life Due to their susceptibility to oxidation from the exposure to oxygen, heat and light, plant oils rich in polyunsaturated fatty acids have a limited shelf-life. Therefore, it is necessary to test their shelf life for theformation of oxidation products, such as peroxides and hydroperoxides.


• These tests will ensure that the oils and fats are pure, edible, free from rancidity and of the right grade. It is essential to test the oils, so as to ensure that its quality is untampered with and it is consumed without any adulteration.

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.

Reference:

https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/edible-oil

http://www.madehow.com/Volume-1/Cooking-Oil.html

https://www.heraldopenaccess.us/openaccess/source-extraction-and-constituents-of-fats-and-oils

https://www.pmg.engineering/edible-oil-an-introduction

https://en.wikipedia.org/wiki/Cooking_oil