冻干荔枝前处理的酶促褐变控制研究

Study on enzymatic browning control of lychee fruits during pretreatment of freeze drying

摘要: 以怀枝荔枝为研究对象,研究了几种预处理方法对荔枝果肉中多酚氧化酶(PPO)和过氧化物酶(POD)活性的影响。结果表明,1mmol/L的谷胱甘肽溶液浸泡降低了PPO和POD活性,但并未使其失活;同样浓度的谷胱甘肽溶液和抗坏血酸溶液真空浸泡(真空度为0.08MPa)也不能使PPO和POD失活;90℃热烫3min以上可以使POD失活;采用0.3%的抗坏血酸溶液在90℃热烫3min以上可以使PPO失活,通过对热烫后冻干荔枝的色泽和脆度测定,确定最佳预处理条件为0.3%的抗坏血酸溶液90℃热烫5min。

Abstract: The effect of several pretreatments on polyphenol oxidase ( PPO) and peroxidase ( POD) activity were studied for Huaizhi lychee. PPO and POD activity were decreased after being immersed in 1mmol /L glutathione solution but the treatment had no effect on PPO and POD inactivity.After being immersed in 1mmol /L glutathione solution and ascorbic acid solution in vacuum condition ( 0.08MPa ) , PPO and POD activity were also not passivated.The treatment of blanching at 90℃ for over 3min could result in POD passivation. The treatment of blanching in 0.3% ascorbic acid solution at 90℃ for over 3min could lead to passivation of PPO. The optimal blanching time was 5min by considering the results of color and crispness of freeze dried lychees.