冷冻甘薯片的护色工艺

Studies on Color-Protecting of Frozen Sweet Potato Slices

冷冻甘薯片在贮藏过程中发生的褐变与多酚氧化酶(PPO)的活性呈正相关.实验研究了甘薯片中多酚氧化酶的性质,并采用各种护色剂抑制甘薯片在冷冻加工过程中产生的褐变.结果表明,甘薯中多酚氧化酶在70 ℃下很不稳定,随着恒温时间的延长,活性迅速降低;甘薯中多酚氧化酶的最适pH值分别为5.0和7.5;甘薯片的最佳护色方法为热处理结合护色剂,L 半胱氨酸是较理想的护色剂,它不仅能够很好地抑制甘薯片在冷冻过程中发生的褐变,而且对甘薯的营养成分如VC具有保护作用.

Browning of sweet potato slices during frozen storage was found to be correlated with polyphenol oxidase(PPO) activity. The aims of this paper were to determine the heat stability and optimum pH of PPO and to find the condition to inhibit browning of frozen sweet potato slices. The optimum pH of PPO was 4.5 and 7.5 and PPO became very unstable above 70℃. The best method to preserve the color of frozen sweet potato slices was to use color preserving agents combining with heat treatment. L-cysteine was the best agent for protecting color and vitamin C.