为了解反复冻融对葡萄出汁率及品质变化的影响,以巨峰葡萄为研究对象,通过测定冷冻-解冻后的出汁率以及榨汁后的浊度、pH值、可滴定酸含量、可溶性固形物含量、色泽和风味等指标的变化,分析反复冻融对果汁品质的影响。结果表明:冻融1次的葡萄出汁率显著高于其他处理组(p<0.05),随着冻融次数的增加,出汁率在逐渐降低;浊度、pH值、可滴定酸含量和可溶性固形物含量均显著高于未经处理的葡萄(p<0.05);经过1次冷冻葡萄的汁液色泽要好于其他处理组;葡萄在冻融处理后汁液中挥发性风味物质含量普遍呈现出下降的趋势,只有无机硫化物在显著增加(p<0.05)。1次冻融处理不仅能够提高出汁率,且获得的葡萄汁品质较好。

Kyoho grape was used in order to explore the effects of repeated frozen-thawed cycles on grape qualities and juice yield.The influence of freezing and thawing technique on the qualities of grape juice was analyzed by the measurements of indexes,such as,turbidity,pH value,titratable acid content,soluble solids,color parameters and flavor components before and after grape frozen-thawed treatment.The results show that,one time frozen-thawed treatment grape has a significant high juice yield(p<0.05).However,the more times of frozen-thawed treatment,the less of juice yield.Moreover,the indexes of turbidity,pH value,titratable acid content,soluble solids of juice by frozen-thawed treatment were significantly higher than untreated group(p < 0.05).The color of one time frozenthawed treatment juice was also better than other groups.In addition,the contents of volatile components in grape juice were generally decreased after frozen-thawed treatment,except the content of inorganic sulphide,which showed a significant increase(p<0.05).In general,one time frozen-thawed treatment was better not only for the increasing of juice yield,but also for the qualities of juice.