紫甘薯贮藏期间多酚氧化酶活性及褐变强度变化的研究

Study on Change of Polyphenol Oxidase Activity and Browning Degree of Purple Sweet Potato during Storage

紫甘薯皮部组织中PPO活性和褐变强度均高于整块和心部。两者显著正相关,相关系数r=0.9895。鲜切紫甘薯PPO活性在贮藏初期有所上升,第3d达活性高峰。此后随着贮藏时间的延长而逐渐下降。贮藏期间样品的褐变度随时间的延长而增加,前3d的褐变十分迅速。分析表明,贮藏期间BD与PPO活性负相关,相关系数r=-0.8747。可知贮藏期间紫甘薯褐变主要是由多酚氧化酶引起的酶促褐变。

The study data showed that the polyphenol oxidase （PPO） activity and browning degree （BD） of purple sweet potatoes peel are higher than those of inner-tissue and intact sweet potato. The relativity between them is positive, and relativity coefficient is 0.9895. Browning degree of fresh-cut purple sweet potato slice during storage period is found to be correlated with PPO activity. The activity of PPO extracted from purple sweet potato increases initially and decreases afterwards, with the highest activity of PPO on the third day. And BD increases very quickly as time going by, especially in the first three days. The relativity between PPO activity and BD is negative, and relativity coefficient is -0.8747.These results showed that the browning of purple sweet potatoes is mainly due to polyphenol oxidase in it.