微环境气调对蓝莓贮藏期软化的调控作用

Regulation of Micro-environmental Modified Atmosphere on the Softeningof Bluberries during Storage

为探讨微环境气调对蓝莓贮藏期果实软化的影响,采用自发气调(mMAP)、1-甲基环丙烯(1-MCP)、微环境气调(mMAP+1-MCP)处理蓝莓,以未经处理的蓝莓为对照。将处理过的蓝莓置冰温库(-0.5±0.3)℃贮藏,分别于贮藏0,20,40 d和60 d时测定果实硬度、细胞壁多糖含量、细胞壁降解酶活性和关键降解酶基因表达量。结果表明:与对照组相比,3个处理组均能显著降低果实的软果率(P<0.05),其中mMAP+1-MCP处理效果最佳。贮藏60 d时果实硬度显著高于其它处理组(P<0.05),维持较高的纤维素和原果胶含量,半纤维素在贮藏前期高于其它处理,而可溶性果胶含量在贮藏中前期保持较低水平。分析细胞壁降解酶,mMAP+1-MCP处理组贮藏40 d时纤维素酶(Cx)、多聚半乳糖醛酸酶(PG)和果胶甲酯酶(PME)活性最低,贮藏60 d时β-半乳糖苷酶(β-Gal)和α-L-阿拉伯呋喃糖苷酶(α-Af)活性显著低于其它处理组(P<0.05)。正交偏最小二乘判别分析(OPLS-DA)表明,mMAP+1-MCP与其它处理组差异性指标为Cx和β-Gal活性。对这两种细胞壁降解酶基因的表达分析结果:mMAP+1-MCP处理可有效延缓蓝莓贮藏过程中Cx和β-Gal基因表达量峰值的出现时间。结论:mMAP+1-MCP形成的微环境气调环境通过延缓Cx和β-Gal基因表达量出峰时间,抑制贮藏后期Cx和β-Gal活性,保持果实的纤维素和原果胶含量,进而减缓果实的软化。

In order to study the effect of micro-environmental modified atmosphere on bluberries during storage,micro-environmental modified atmosphere package(mMAP),1-methylcyclopropene(1-MCP)and micro-environmental modified atmosphere package combined with 1-methylcyclopropene(mMAP+1-MCP)were used to treat bluberries,and the untreated blueberries were used as control.The blueberries after treated were stored in cold storage(-0.5±0.3)℃,and fruit firmness,contents of cell wall polysaccharide,activities of cell wall degrading enzyme and key degrading enzyme gene expression were measured at 0,20,40 and 60 day during storage.The results showed that the three treatments could significantly reduce the soft fruit rate compared with the control group(P<0.05),and the effect of mMAP+1-MCP treatment was the best.The fruit firmness of mMAP+1-MCP treatment was significantly higher than other treatments(P<0.05),with higher content of cellulose and protopectin.The hemicellulose of it was higher than other treatments in the early stage of storage while the soluble pectin content remained lower in the early and medium stage.According to the analysis of cell wall degrading enzymes,the activities of cellulase(Cx),polygalacturonases(PG)and pectinmethylesterases(PME)of mMAP+1-MCP treatment group were the lowest at 40 day of storage,and the activities ofβ-galactosidase(β-Gal)andα-L-arabinofuranosidase(α-Af)of mMAP+1-MCP treatment were significantly(P<0.05)lower than those of other treatments during 60 day.Orthogonal partial least squares discriminant analysis(OPLS-DA)showed that the differences between mMAP+1-MCP treatment and other treatments were Cx andβ-Gal,the expression of the two key cell wall degrading enzymes was analyzed and the results showed that mMAP+1-MCP treatment could effectively delay the time which peak value occurs of Cx andβ-Gal genes during storage of blueberries.Therefore,the mMAP+1-MCP treatment could delay the time which peak value occurs of the gene expression of Cx andβ-Gal and inhibit the activities of Cx andβ-Gal in the late stage of storage,maintaining the contents of cellulose and pectin,and then slow down the softening of fruits.