以紫甘薯为原料,通过单因素试验和正交试验研究全质紫甘薯汁制备中的护色及增色技术。以L*(明度值)和△E*(总色差值)为标准,就3种单一护色剂(抗坏血酸,柠檬酸,富马酸)和复合护色剂对全质紫甘薯汁的护色及增色效果进行试验,并研究酶解过程对全质紫甘薯汁色泽的影响。试验结果显示:抗坏血酸、柠檬酸都有护色的效果,且复合护色剂的护色效果比单一护色剂好;(富马酸未能起到护色作用。最佳复合护色剂为:0.45%抗坏血酸+0.6%柠檬酸。此条件下护色后进行酶解,最终得到色泽清亮鲜艳且澄清的全质紫甘薯汁。

Purple sweet potato was used as the raw material to investigate the color-protecting technology and coloring in the preparation processing of purple sweet potato juice by single factor experiment and the orthogonal experiment.The study was also explored on the lightness and color differences.Three single color fixative and compound color fixative were chosen for the experiment.The effect of enzymolysis on the color of purple sweet potato juice was studied.Results indicated that ascorbic acid and citric acid had effects on enhancement and protection,and compound color fixative was bette3r than single color fixative.The compound of 0.45% ascorbic acid and 0.6% citric acid had the best effect.Enzymolysis was performed after color-protecting and an excellent sweet potato juice with attractive color,flavor and taste was prepared.