Enzymatic hydrolysis of diglycerides in refining and modification process for better oil quality

Abstract: Free fatty acid is high in crude edible oils when triglycerides are hydrolyzed by an action of lipase, heat and moisture. The breakdown of triglycerides will generate free fatty acid and diglycerides. Free fatty acid can be removed by subsequent chemical neutralization or physical refining process. However, the extra diglycerides generated cannot be removed by either step or remains in the refined oil.

Glycidol ester (GE) is known to be genotoxic and carcinogenic. Europe impose a GE of 1ppm max in edible oil since 2018. Diglycerides is the main precursor for GE formation. Crude palm oil and crude rice bran oil are high in free fatty acid and diglycerides content in general. Crude rice bran oil contains 5-10% free fatty acid and 6-9% diglycerides. If an enzyme process can reduce the diglycerides level down to 2-3%, it will help to minimize the GE formation in the deodorization step. Dewaxing and winterization process are required to produce a better cold stability of rice bran oil. Some of the higher melting point diglycerides will crystallize out together with waxes and high melting point triglycerides. By removing some diglycerides with enzyme during the degumming process, this could potentially improve the oil yield by reducing oil entrapment in the dewaxing and winterization process. For the similar reason, low diglycerides content in palm olein also improves the cold stability.

NS88007 is capable of hydrolyzing diglycerides and monoglycerides to free fatty acid with minimum water present. At the right conditions, there are no triglycerides being hydrolyzed. With that, it is specifically hydrolyzing diglycerides and monoglycerides. NS88007 can also be added into the enzymatic degumming of rice bran oil. This will help to reduce the phosphorus content as well as the diglycerides content in enzyme treated rice bran oil. NS88007 also does not cause any interesterification reaction and the triglycerides composition unchanged.