Preparation of human milk fat analogue by enzymatic interesterification reaction using palm stearin and fish oil

摘要

Palm stearin fractionate (PSF), obtained from palm stearin by further fractionation with solvents and n-3 polyunsaturated fatty acids (n-3 PUFA) rich fish oil (FO) were subjected to interesterification at 1:1, 1:2, 1:3, 2:1 and 3:1 substrate molar ratio and catalyzed by lipase from Thermomyces lanuginosa for obtaining a product with triacylglycerol (TAG) structure similar to that of human milk fat (HMF). The parameters (molar ratio and time) of the interesterification reaction were standardized. The temperature of 60 °C and enzyme concentration of 10 % (w/w) were kept fixed as these parameters were previously optimized. The reactions were carried out in a stirred tank reactor equipped with a magnetic stirrer for 6, 12, 18 and 24 h. The blends were analyzed for fatty acid (FA) composition of both total FAs and those at the sn-2 position after pancreatic lipase hydrolysis. All the blended products were subjected to melting point determination and free fatty acid content. Finally, blend of PSF and FO at 2:1 molar ratio with 69.70 % palmitic acid >(PA) content and 12 h of reaction produced the desired product with 75.98 % of PA at sn-2 position, 0.27 % arachidonic acid (AA), 3.43 % eicosapentaenoic acid (EPA) and 4.25 % docosahexaenoic acid (DHA) and with melting point of 42 °C. This study portrayed a successful preparation of TAG containing unique FA composition i.e. ≥ 70 % of the PA, by weight, were esterified at the sn-2 position which could be used in infant formulation with health benefits of n-3 PUFAs.