【作者】 孙丽娟； 赵光远； 崔政伟；

【Author】 SUN Lijuan 1, ZHAO Guangyuan 2, Cui Zhengwei 1,2 ( 1. Food Engineering & Machinery Group, School of Mechanical Engineering, Southern Yangtze University, Wuxi 214122 2. School of Food Science and Technology, Southern Yangtze University, Wuxi 214122)

【机构】 江南大学机械工程学院； 江南大学食品学院；

【摘要】 苹果破碎时蒸汽热处理使果浆温度在80秒内达92℃以上不但可以改善浑浊苹果汁色泽且可增强果汁的浑浊稳定性。果汁的颜色明显受果浆升温速率和果浆所达到的最高温度影响,果浆最高温度明显影响果汁的粘度和果胶含量。苹果浆温度达92℃和95℃虽然维生素C损失较多,但PPO热失活后在果汁自身的pH条件下已没有活力,因而得到的果汁的总酚损失较小,L值分别为29.24和30.44(对照为19.0),a值分别为-4.03和-3.03且有好的色泽稳定性(△E分别为0.39和0.29,对照为4.3)。苹果破碎过程中的发生的褐变主要为酶促褐变。随着果浆温度的升高,得到的果汁的浊度和粘度升高。这主要由于高温增加了果浆中果胶的释放。果汁的浊度测量受离心力和离心时间影响,但经4200r/min离心15min以上其浊度不再显著降低。更多还原

【Abstract】 The color and cloud stability of cloudy apple juice could be improved greatly when it was made by heating the pulp to above 92℃in 80s .The color of juice was affected greatly by the highest treated temperature and the temperature-increasing ratio of the pulp, and the viscosity of juices and the content of pectin in the juices were obviously affected by the highest heating temperature of the pulp. Though Vc in the pulp lost more when being heated to 92℃ or 95℃,the total phenols in the juices made from the pulp lost less and the L value of juices was 29.4 and 30.44 respectively(the control was 19.0),the a value of juices was –4.03 and –3.03 respectively as well as the juices had good color stability(△E for juices was 0.39 and 0.29, △E for control was 4.3)for that PPO in juices had lost its activity and had no activity in the nature pH environments of juices. The browning occurring in juices was mainly enzymatic browning. The viscosity and turbidity of juices increased as the temperature of the pulp increased mainly for that heat treatment of increased temperature could free more pectin from the pulp to juices. The pulp treated with citric acid before making juices could free more pectin to juices, and the content of protein in the cloud of juices increased as well as some changes occurred for the amino composition of the protein, so, the viscosity and turbidity of juices increased compared with the samples of not being acidified. The result of measuring for juices turbidity was effected by centrifuge force and centrifuge time used in the test. If the juices were centrifuged for more than 15 min in 4200g before measuring, the turbidity of them would not decrease.更多还原