To optimize the ethanol extraction conditions of floridoside and to investigate the effect of floridoside on the myofibrillar protein freezing denaturation of grass crap surimi during frozen storage.Ethanol concentration,extraction temperature,extraction duration and liquor to material ratio were optimized by response surface methods.The salt-solubility of myofibrillar protein,sulfhydryl content,and Ca2+-ATPase activity,etc in surimi after being frozen for 6 weeks were detected.Results showed that the optimal extracting condition for floridoside was 72.3％ ethanol with liquor to material ratio of 14:1 (mL/g),the extracting tempreture was 60 ℃C,and the extracting time should be 4 h.Under these optimal conditions,the highest extraction ratio was 3.48％.Salt-soluble protein,sulfhydryl group contents,Ca2+-ATPase activity were effectively enhanced,and the water loss was decreased by addition of floridoside in surimi.After 4 weeks frozen,salt-soluble protein and sulfhydryl group contents were enhanced by 30.62％ and 32.80％;Ca2+-ATPase activity in myofibrillar proteins was reduced by 37.51％ in 10％ floridoside treated group,while the water loss ratio was 133.07％ lower than that of the control group.This study indicates that floridoside can effectively prevent myofibrillar protein denaturation during frozen storage.%为探讨红藻糖苷的醇提工艺以及红藻糖苷对冷冻草鱼鱼糜蛋白变性作用的影响,首先采用响应面分析法对乙醇浓度、提取温度、时间和液料比4个因素进行优化,随后以冷冻鱼糜的盐溶性蛋白含量、巯基含量及肌原纤维蛋白Ca2+-ATP酶活性等参数为指标,探测冷冻草鱼鱼糜在冷藏过程中添加红藻糖苷对蛋白质变性作用的影响.结果显示,红藻糖苷的最佳醇提条件为乙醇72.3％、提取温度60℃C、时间4h、液料比14∶l(mL/g),在此条件下的提取率为3.46％;抗冻性能结果显示,随红藻糖苷浓度升高,抗冻效果增强;以10％红藻糖苷处理冷冻鱼糜4周后,盐溶性蛋白含量和巯基含量分别比空白组高30.62％、32.80％,肌原纤维蛋白的Ca2+-ATP酶活性的下降率比空白组低37.51％,解冻失水率的增长率比空白组低133.07％.研究表明,红藻糖苷能有效延缓草鱼鱼糜肌原纤维蛋白的冷冻变性.
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