| 摘要 |
<p>A two-stage method for the preparation of polyol fatty acid polyesters is provided. The resulting polyol fatty acid polyesters are very lightly colored (i.e., colorless to slightly yellow) and have a high degree of substitution with fatty acid groups. The first stage of this two-stage method is a solvent-based esterification reaction; the second stage is an essentially solvent-free esterification reaction. In the first stage, a polyol in a solvent (e.g., sucrose in dimethylsulfoxide)) is reacted with fatty acid lower alkyl esters at relatively low temperatures using an alkaline salt catalyst. After the desired degree of esterification is obtained, the resulting partially-esterified polyol fatty acid polyesters and the solvent-containing phase are separated. The separated partially-esterified polyol fatty acid polyesters are further esterified with the same or different fatty acid lower alkyl esters in a second stage with an alkaline salt catalyst using essentially solvent-free, high temperature conditions whereby the degree of substitution is significantly increased. Most of the color bodies and other contaminants capable of producing color are removed with the solvent in the first stage and, therefore, are not present during the higher temperature reaction conditions of the second stage. The resulting polyol fatty acid polyesters, and in particular the sucrose fatty acid polyesters, are especially useful as fat substitutes in food applications and products. <IMAGE></p> |
