超高压加工鲜榨苹果汁过程中的主要理化变化

在50℃协同320MPa加工鲜榨苹果汁的过程中,利用果汁的L*值和b*值升高,a*值降低,但幅度均不大。高效液相色谱(HPLC)等方法测定表明:酚类在加工中由于氧化而减少,果汁中单宁、绿原酸、总酚和表儿茶素的保留率(与原料对比)分别为80.2%、82.4%、78.2%和82.6%。还原型V_c和总V_c分别减少43.7%和6.1%。气/质联用(GC-MS)的检测和分析表明:热协同压力处理鲜榨苹果汁后各风味成分变化在0.28%～6.16%,总风味物质压后比压前仅下降0.78%,酯类物质在压后含量增加。50℃协同320MPa加工工艺能较好地保持苹果汁的品质。

The Physical and Chemical Changes During High Pressure Extracting Processing of Fresh Apple Juice

During the processing of 320MP pressure at 50℃in fresh apple juice extraction,there was no obvious increase of L~*-value and b~*-value and decrease of a~*-value.HPLC analysis showed that the amount of polyphenols in juice was decreased because of oxidization.The amount of polymeric and mono proanthocy- anidin,chlorogenic acid,totol phenols and epicatechin in cloudy apple juice retained 80.2%、82.4%、78.2% and 82.6% respectively.The reduced VC and total VC decreased 43.7% and 6.1% respectively.The volatile components changed in the scope of 0.28～6.16% and the total volatile component only decreased 0.78%, the amount of esters increased.The process condition of 320MP at 50℃was the best condition to maintain the quality of fresh apple juice.