热烫处理对鲜切根茎菜品质的影响

研究热水热烫和蒸汽热烫(温度为100 ℃，处理时间均为5、10、15、20 s)对土豆、藕、白萝卜中多酚氧化酶(PPO)的活性以及褐变强度(BD)的影响，并对真空包装下3种根茎菜在4 ℃贮藏下微生物生长及品质变化情况进行了研究。主要实验结果如下:2种热烫方式均可以有效抑制3种鲜切菜的褐变，但蒸汽热烫对PPO活性钝化效果较热水热烫更为显著，蒸汽处理15 s后PPO残留活性下降至30%以下，而热水热烫20 s后PPO残留活性仍然在50%以上；在贮藏期间，随着贮藏时间的延长，3种鲜切菜的硬度显著下降，而微生物数量和总色差显著上升。当贮藏7 d时，白萝卜的硬度变化最大，下降了23.3%；藕的微生物数量增长最大，增加了1.75个对数；土豆的总色差值(ΔE)增加最多，为33.49。实验结果表明，采用蒸汽热烫处理3种鲜切菜，能有效抑制褐变，有效地保持蔬菜品质。

Effect of Blanching Treatments on the Quality of Fresh-cut Root Vegetables

The effects of hot water blanching and steam blanching (100℃, treatment time 5 s, 10 s, 15 s, 20 s) on polyphenol oxidase (PPO)activity and browning degree (BD) in fresh cut potato, lotus root and white radish were studied. The main experimental results are as follows: Both blanching methods can effectively inhibit browning of three fresh cut vegetables. However, the inactivation of steam blanching on the PPO activity was more effective than that of hot water blanching. After 15 seconds of steam blanching, the residual PPO activity was below 30%, but residual PPO activity was still above 50% after 20 s of hot water blanching for 20 s. During storage, the hardness of the three fresh cut vegetables was decreased while the microorganism and total color difference were increased with increasing storage time. At 7 d, the hardness of radish decreased by 23.3%. The number of microorganisms in lotus root increased by 1.75 logarithms. The total color difference of potatoes ΔE increased the most, to 33.49. These results show that steam blanching can effectively inhibit browning and keep the quality the three fresh cut vegetables.