不同品种梨汁酶促褐变因子及相关性  

Enzymatic Browning Factors of Pear Juice in Different Varieties and Its Correlation with Enzymatic Browning

作　　者：张亚伟[1] 陈义伦[1] 

机构地区：[1]山东农业大学食品科学与工程学院,山东泰安271018

出　　处：《中国农业科学》2011年第9期1880-1887,共8页Scientia Agricultura Sinica

基　　金：国家公益性行业(农业)科研专项(nyhyzx07-026)

摘　　要：【目的】明确不同品种梨汁酶促褐变的理化因子(相关酶活性、底物组成和含量、pH),并由相关性分析探讨梨汁酶促褐变主要原因,为品种选择和褐变控制提供理论依据和技术支持。【方法】以鸭梨、长把梨等7种梨为原料,测定梨果实中多酚氧化酶(PPO)、过氧化物酶(POD)、苯丙氨酸转氨酶(PAL)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)等5种褐变相关酶的活性,总酚含量,梨果实的pH以及鲜榨梨汁的色值(T440);用HPLC法鉴定梨果实中酚类物质的种类。【结果】供试7个品种梨汁的酶促褐变程度存在很大差别,黄冠梨和黄金梨汁褐变较轻,雪梨和水晶梨汁褐变较重。不同品种梨汁酶促褐变的主要相关酶不同,并且不同品种梨果实中的酶促褐变相关酶活性存在较大区别。梨果实的总酚含量以及与梨汁褐变的相关度因品种而异;供试的梨果实中的酚类物质主要是(+)-儿茶素、绿原酸和香豆素,且不同品种的酚类组成不同。不同品种梨果实的pH存在差异,梨汁的色值与果实的pH均呈显著相关。【结论】不同品种梨汁的酶促褐变程度有很大差别。梨果实中褐变相关酶类的活性、酚类物质含量和组成以及对梨汁酶促褐变的影响程度因品种而异,梨汁的酶促褐变与酶类的相关度高于与总酚含量的相关度。梨汁酶促褐变与梨果实的pH呈显著相关。【Objective】The objective of this experiment is to determine the physical and chemical factors（related enzymes,substrate composition and content,pH） of enzymatic browning in pear juice of different varieties,probe into the main factors by correlation analysis,and provide a theoretical and technical basis for the browning control and the species selection.【Method】With 7 varieties of pears（Yali pear,Changba pear,et al.） as the raw materials,activities of 5 kinds of enzymes（PPO,POD,PAL,CAT and APX） related to enzymatic browning,total phenols,pH values of pear fruit and color value（T440） of pear juice were studied,the contents of phenolic compounds in pear fruits were analyzed using HPLC.【Result】 The enzymatic browning in pear juice of the tested seven varieties was different,juice of Huangguan pear and Whangkeumbae browning was lighter,and Sydney and Suisho pear was heavier.The major related enzymes in pear juice of different varieties were different,and there were big differences in activities of enzymes related to enzymatic browning in pear fruits of different varieties.Total phenols content in pear fruits and its relationship with enzymatic browning in pear juice of different varieties varied;the phenolic compounds in pear fruits mainly were（＋）-catechin,chlorogenic acid and coumarin,contents of phenolic compounds in pear fruits of different varieties were also different.pH values of pear fruit of different varieties were unequal,color value of pear juice showed a significant correlation with pH value of pear fruit.【Conclusion】The enzymatic browning in pear juice of the tested seven varieties was different.Activities of enzymes related to enzymatic browning,total phenols content in pear fruits and the effect of them on pear juice enzymatic browning differed among different varieties,the correlation of enzymes to enzymatic browning in pear juice was higher than total phenols content.Color value of pear juice showed a significant correlation with pH value of pear fruit.

关 键 词：梨汁 酶促褐变 褐变相关酶 酚类物质 PH 

分 类 号：TS255.44[轻工技术与工程—农产品加工及贮藏工程]