解冻方式对苹果汁理化品质及挥发性成分的影响

Effects of Thawing Methods on the Physicochemical Quality and Volatile Aroma Compounds of Apple Juice

为探究解冻方式对苹果汁品质及挥发性成分的影响,比较室温空气、室温静水、室温超声、低温空气、低温静水和低温超声6种解冻方式对苹果汁解冻过程、品质特性及挥发性成分的影响,并用主成分分析法对结果进一步分析。结果表明:总解冻时间由长至短依次为:空气解冻>静水解冻>超声解冻,且室温组均短于低温组。解冻方式对苹果汁的色差、可溶性固形物、可滴定酸及还原糖的影响差异不显著(P>0.05)。空气解冻苹果汁的总酚含量显著下降,静水和超声解冻总酚含量无显著性差异(P>0.05)。与室温解冻相比,低温解冻后,苹果汁的总酚含量更低(P<0.05)。低温解冻的苹果汁中,2-甲基丁基乙酸酯含量最高,占总香气成分的56%~64%,而室温解冻的苹果汁中未检测到该物质,说明低温解冻可较好地保留苹果香气分成。综上所述,在低温条件下采用超声解冻可缩短解冻时间,最大程度保留苹果汁中的营养成分和风味。

In order to explore the influence of thawing conditions on the quality of apple juice,the physicochemical properties and volatile aroma components content of apple juice after thawing by 6 methods were analyzed.Besides,principal component analysis was used to evaluate the relationships between indexes.The results are as follow:Still air thawing took the longest time,followed by static water thawing and ultrasonic thawing.Compared with thawing at room temperature,thawing at low temperature took more time.There was no significant difference in color,soluble solid content,titratable acid content and the reducing sugar content of apple juice after thawing by different thawing methods(P > 0.05).The content of polyphenol in apple juice thawed in still air decreased significantly,while there was no significant difference in polyphenol content between static water and ultrasonic thawing(P > 0.05).The content of polyphenols in apple juice that thawing at low temperature was less than that of thawed at room temperature(P < 0.05).Under low temperature,2-methyl butyl acetate was the most abundant among all volatile aroma compounds in apple juice,which accounted for 56%-64% of the total aroma components.However,the substance was not detected in that at room temperature,indicating that thawing at low temperature contributed to the retention of apple juice aroma components.This study showed that,under low temperature conditions,ultrasonic thawing can shorten the thawing time,and can retain the nutrients and color in apple juice.