荔枝护色干制的工艺研究

    Technology of litchi rind color retention during hot air drying of litchi fruit

    • 摘要: 果皮褐变是荔枝贮藏和加工过程中的常见问题。在探讨了荔枝果皮中引起褐变的主要酶——多酚氧化酶(PPO)特性的基础上着重研究了荔枝干制中的护色工艺。结果表明,荔枝果皮多酚氧化酶的最适温度范围为30~70℃之间;PPO在pH=5.5和pH=7.0左右活性最大。荔枝经90℃,0.2%的柠檬酸溶液中热烫3 min并强制冷却后,用0.2 mol·L-1抗坏血酸+0.2 mol·L-1柠檬酸+0.1 mol·L-1植酸+0.1 mol·L-1氯化钠+0.2 mol·L-1亚硫酸氢钠混合液护色处理10 min经脱水干燥制成天然红皮荔枝干。

       

      Abstract: Browning of litchi rind is a general problem during the storing and processing of litchi fruit. The characteristics of polyphenoloxidase (PPO) which causes the browning of litchi rind was investigated and then the experiments on the production procedure for color retention of dried litchi fruit were conducted. The results showed that optimum temperature of PPO was 30~70℃, optimum pH values of PPO were about pH=5.5 and pH=7.0. ascorbic acid, citric acid, phytic acid, sodium chloride and sodium bisulfite were used as color retention agents in this study. The orthogonal experiment shows that the relatively optimum composition of these five agents is as follows: 0.2 mol/L Ascorbic acid + 0.2 mol/L Citric acid +0.1 mol/L Phytic acid +0.1 mol/L Sodium chloride +0.2 mol/L Sodium bisulfite. The fresh litchi, after color retention treatment, was finally dried using hot air to produce dried litchi fruit with natural red rind.

       

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