2种预处理方法对‘秦冠’苹果果实细胞壁物质降解和出汁率的影响

Effects of two pre-treatments on the degradation of cell wall composition and juice yield of "Qinguan" apple fruit

【目的】研究以外源乙烯为主的预处理对‘秦冠’苹果果实细胞壁物质降解和出汁率的影响,为开发新的苹果果汁加工工艺提供依据。【方法】以‘秦冠’苹果果实为试材,采用500mg/L乙烯利(E1)和100mg/L乙烯利配合60℃热水(E2)处理后,于室温堆放,以蒸馏水处理为对照(CK),每3d测定1次多聚半乳糖醛酸酶(PG)、果胶甲酯酶(PME)、纤维素酶(CS)和木聚糖酶(Xyl)活性及细胞壁物质含量和果实出汁率。【结果】E1处理苹果果实的PG、PME、CS和Xyl活性均较对照逐渐提高,分别于第12,12,9,6天出现高峰。处理12d后,E1果实细胞壁多糖中,果胶类多糖以CDTA-2溶性部分降解、半纤维素类多糖中以KOH-1溶性部分降解最多,含量分别降为对照的82.1%,81.2%;细胞壁物质总体较对照降低88.1%;出汁率较对照增加4.7%～5.6%。E2处理果实0d时各种酶活性明显增强,峰值较E1出现更早,但后期衰减更快;12d后各类细胞壁多糖下降幅度大于E1(KOH-3除外);E2处理对苹果果实出汁率的提高效果尤为明显,9d时出汁率高于对照7.5%,但18d后出汁率反而降至对照水平。【结论】500mg/L乙烯利处理是一种节能、简便且有效的可持续提高‘秦冠’果实出汁率的措施。

【Objective】 Effects of exogenous ethylene based pre-treatments on the degradation of cell wall of＂Qinguan＂apple fruit were investigated to increase its juice yield.【Method】 After being treated under two sets of conditions： 60 ℃ water with 500 mg/L ethrel（E1） and 100 mg/L ethrel（E2）,＂Qinguan＂apple fruits were placed in open plastic box under room temperature.The activities of polygalacturonase（PG）,pectin methylesterase（PME）,cellulose（CS）,xylanase（Xyl）,and contents of cell wall compositions as well as juice yield were determined every three days.【Result】 E1 elevated the activity of PG,PME,CS,and Xyl in comparison to control group.The four enzymes reached peak on 12th,12th,9th,and 6th day,respectively.On day 12,the contents of CDTA-2 part among pectins KOH-1 part among hemicelluloses,and total CWM-residue degraded to 82.1%,81.2%,and 88.1% to that of control group,respectively,while the juice yield increased by 4.7%-5.6%.E2 increased the enzyme activity right after treatment,and PME and Xyl peaked earlier than that of E1.All the cell wall components of E2 except KOH-3 decreased more than that of E1.Juice yield of E2 was 7.5% higher than the control group on day 9 but it reduced to the same as control group on day 18.【Conclusion】 Pre-treatment with 500 mg/L ethrel（E1） was an energy-saving and simple approach to increase the juice yield effectively and persistently.