将棕榈硬脂和甲醇钠分别作为原料和催化剂,经过化学法催化棕榈硬脂进行酯交换反应,制备sn-2位富含棕榈酸的甘油三酯,为制备人乳脂替代品提供原料.首先对原料棕榈硬脂中的脂肪酸含量及分布进行测定并分析,然后通过单因素试验,确定了反应时间、甲醇钠添加量和反应温度3个因素的水平范围,接着再根据Box-Behnken中心组合试验设计原理设计响应面试验,对甲醇钠催化棕榈硬脂发生酯交换反应的工艺条件进行优化.结果表明:3个因素对试验结果均有显著影响,影响顺序为反应时间＞反应温度＞甲醇钠添加量.当反应时间为33 min,甲醇钠添加量为0.33％,反应温度为83℃时,酯交换所得产物中sn-2位棕榈酸含量达到60.17％,比原料棕榈硬脂中sn-2位棕榈酸含量增加了21.37个百分点,可作为制备人乳脂替代品的理想原料.%The preparation of triglycerides rich in palmitic acid at sn-2 position was conducted through chemical interesterification in the present study,while palm stearin was used as the raw material and sodium methoxide as catalyst.The content and distribution of fatty acids in the raw material palm stearin were measured and analyzed first.And then the horizontal ranges of reaction time,sodium methoxide load and reaction temperature were determined by single factor experiments,which were further optimized by Box-Behnken center combination experiments.The results showed that the three factors all had significant effect on the content of palmitic acid at sn-2 position,and the order of the impact was reaction time ＞ reaction temperature ＞ sodium methoxide load.The optimal reaction conditions were as follows:reaction time 33 min,sodium methoxide load 0.33％ and the reaction temperature 83 ℃.Under the above parameters,the sn-2 palmitic acid content of the obtained triglycerides could reach to 60.17％,which was increased by 21.37 percent point compared with the raw palm stearin.The afforded triglycerides rich in palmitic acid at sn-2 position could be used as ideal raw material for the preparation of substitute of human milk fat.
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