Preparation of chocolate containing linolenic acid by enzymatic interesterification and its properties

The interesterification of cocoa butter and flaxseed oil with mass ratio 38∶ 3 was catalyzed by immobilized lipase Lipozyme TLIM and the melting point of the resulting lipid( named as interesterified cocoa butter) was( 36.52± 0.34) ℃. The linolenic acid content of the interesterified cocoa butter increased from 0.64% ± 0.01% before reaction to 3.10% ± 0.28%,but the content of major triacylglycerols of POP,POS and SOS decreased from 84.52%to 62.72%.The content of low melting point triacylglycerols of UUU and SUU increased from 0.92% and 6.85% to10.94% and 16.60%,respectively. In the range of 5 ~ 30 ℃,the solid fat content( SFC) of the interesterified cocoa butter was lower than that of natural cocoa butter,however,its variation trend of SFC with temperature was consistent with that of natural cocoa butter.When the temperature was above 34 ℃,the SFC of interesterified cocoa butter was a little greater than that of natural cocoa butter and the SFC of interesterified cocoa butter was 1.64% at37 ℃. The chocolate containing linolenic acid prepared by the interesterified cocoa butter had fine and smooth surface,good taste with special flavor of cocoa butter and flaxseed oil. The results of accelerated oxidation test indicated that the shelf life of the resulting chocolate was 428 days at 20 ℃,approximately 61 weeks,which had good storage stability.