Soya beans are a very rich form of protein originally from its Asian origin transcended to be widely cultivated form of legume globally. Soya beans are also used as an alternative to meat and are included in many vegetarian dishes. Soya is the main source of Soybean oil, Soymilk, tofu, and Soy Protein. Soybean oil is one of the most common and rich in Omega-3 fatty acids and a good source of Vitamin-E.

Extraction of Oil from Soya beans

The Process and What it entails

What Happens at the factory level

Yielding and Cleaning

After the cultivation, the beans are transported to the factory for the very first process of cleaning to remove dirt, weeds, and other unwanted particles. The cleaning process undergoes into a magnetic field to separate any iron particles. The soybeans are dried in natural sunlight or heated to a temperature between 60 -88 degree Celsius (140-190 degree Fahrenheit) to coagulate the soy protein which makes the extraction process easier.  

Conditioning

Then the dried beans are dehulled or cracked followed by rolling into flakes adjusting the moisture content before sending it to the extraction process. The hull needs to be removed as they absorb oil and gives a lower yield.

Extraction

After these processes, the flakes are loaded in the percolation extractors making the soybeans immersed in solvent normally hexane. The extraction is successive by carrying the extracted flakes in a sealed conveyer for concurrent washes by hexane solvent in enclosed vessels by passing jacket and sparge steam.

The hexane solvent is removed from the soybean oil using evaporators and a final vacuum distillation. The evaporated hexane is recovered from the meal and the oil in condensers and returned to the extraction process. The plant is completely sealed and vapor-proof. After hexane removal, the meal contains only 1% of soybean oil and the meal is sent to produce other products such as soy protein or used as animal feed. The hexane free soybean oil is in the form of crude oil which is further purified.

Refining

The crude soybean oil contains many impurities that need to be removed. There will be two forms of impurities like oil-insoluble and oil-soluble, the oil-insoluble residues are removed by filtering the whole crude oil which separates the impurities. Then for the oil-soluble impurities the oil goes under different process which includes degumming (phosphatides removal), Alkaline wash to remove free fatty acids, colorants, gums etc) and bleaching with activated carbon to remove the color and other impurities.

Quality Check

Mostly oil manufacturers conduct a stringent quality analysis to ensure the right product to the consumers. The oil quality is measured in terms of free fatty acids, the absence of hexane, chemical free, the color of the oil, and the taste test

Hydrogenation (To increase fat)

Soybean oil is not hydrogenated normally and this is an optional process to increase fat which is used to produce food which requires more solid fat contents.

In some manufacturing plant, the refined oil is sent to another optional section called hydrogenation. This process of hydrogenation will increase the stability of soybean oil which makes it less liquid. However, this process increases the saturated fats and will reduce the favorable unsaturated fats. This could create health problems as it generates trans-fats. Thus hydrogenated soybean oil is used in preparing foods which require more solid fat such as margarine.