The use of edible oils started when humans produced fire for cooking purposes for times unknown. Since it makes the food tasty, healthy cooking oils for making food worldwide are critical. Hence the global edible oil market will grow at a CAGR of 4.8% to 268.9 from 212.6 billion US dollars. India contributes over 10% of the global market to reach 28.23 from 20.65 US dollars from 2023 to 2027 growing at a CAGR of 7.63%. With the rapid rise in the edible oil industry, it is essential to know the refining processes of crude oil. Removing the impurities of the crude oil is the job of the refining processes, of which edible oil bleaching is the third step. Since refining crude oil to remove impurities is crucial, knowing about the bleaching process.
In this article, let us discuss the best bleaching process in oil refining using the best equipment to reduce costs and increase oil purity to have no impurities but with all essential nutrients.
What is the bleaching of edible oil?
In ancient times animal fats, upon heating, produced oil to make the food tasty. But with many plant-based edible oils like soya beans, sunflower, groundnut, and others becoming popular, refining these oils became important. Refining involves many processes, like degumming, dewaxing, or neutralization, followed by edible oil bleaching. After bleaching, it is deodorizing or deacidification. GE or 3MCPD mitigation makes the edible oil transparent and looks appealing and tasty with all the nutrients but without the impurities. Hence bleaching of edible oil is the third step of the refining process to purify coloring pigments of chlorophyll along with carotenoids, trace materials, gums, soap, etc., and decomposes oxidation products.
How to do the bleaching of edible oil?
Before knowing the bleach process of oil refining, it is essential to know about bleaching earth or clays. It accounts for almost 5% of the bleaching costs as it helps to remove the impurities left after the neutralization refining process. The bleaching earth has three clay material types: attapulgite, bentonite, and sepiolite. These minerals act as absorbers depending on their mineralogical structure and properties like porosity, particle size distribution, surface area, and activity. The minerals are the natural adaptation of volcanic ash in many mines worldwide.
After knowing about the bleaching earth, it is time to know about the bleaching process of oil refining. There are two types of dry and wet bleaching of refined oil. Dry bleaching involves heating oil, mixing with activated carbon, or bleaching earth. The entire process gets performed under a vacuum to prevent oxidation. Since dry bleaching is expensive, most manufacturers use continuous wet bleaching processes to purify edible oil. Though the investment is higher than dry bleaching, many prefer wet bleaching.
The wet bleaching of refined oil keeps the bleaching earth under suspension to avoid dead areas, resulting in its consumption to reduce costs. Doing it in machines with unique designs by reputed manufacturers does not require mechanical agitation to bleach refined oil under optimal moisture content conditions. The bleaching process of oil refining includes heating oil between 120 to 130 C. The powdered bleaching clays or earth in the water get mixed with the oil to absorb the impurities. After the bleaching process, the oil refining continues with deodorization, deacidification, and hydrogenation to make it suitable for consumption without any harm.
Mectech, the leading manufacturer of machines for bleaching process of oil refining oil and others for the past nearly 45 years, is the market leader with four state-of-the-art facilities and exporting to many countries.
