真空结合热处理对西瓜汁抗氧化活性的影响

Antioxidant activity of watermelon juice affected by thermal and vacuum treatment

为了研究氧气和温度对西瓜汁抗氧化活性的影响,采用真空结合高低温对西瓜汁进行处理。结果表明,在真空和非真空热处理条件下,西瓜汁多酚氧化酶(PPO)的活性随着处理时间和温度的增加呈逐渐下降的趋势;在同一温度和处理时间条件下,真空和非真空处理西瓜汁中PPO的残存活性差异不显著(p>0.05)。并且在30℃,无论真空或非真空条件下,西瓜汁中番茄红素含量、对DPPH自由基清除率和Fe2+螯合率变化均较小;而在70℃真空条件下,西瓜汁中番茄红素含量、对DPPH自由基清除率和Fe2+螯合率的降低均较小,70℃非真空条件下,各指标变化均较大。说明氧气对西瓜汁中PPO活性的影响较小,而真空对其番茄红素含量可以起到一定的保护作用,从而保持对DPPH自由基清除率和Fe2+螯合率稳定。

In order to investigate the effect of oxygen and temperature on antioxidant of watermelon juice, vacuum with tligh and low temperature treatment was applied. Under vacuum and non-vacuum thermal treatments,PPO activity of watermelon juice decreased with treatment time and temperature. And the differences of PPO activities of watermelon juice after vacuum and non-vacuum treatments were not significant at the same temperature and treatment time（p〉0.05）. At 30℃,lycopene content, DPPH free radical scavenging ratio,and Fe^2＋ chelate ratio did not change significantly regardless of vacuum or non-vacuum. While the indexes above decreased slightly at 70℃ of vacuum condition,but that decreased greatly at 70℃ of nonvacuum condition. It suggested that oxygen had little effect on PPO activity of watermelon,and lycopene could be protected under vacuum condition.