壳聚糖和纳米SiOx处理对采后脐橙果实硬度的影响

探讨壳聚糖、纳米SiOx及两者复合处理对采后“Fengji”脐橙果实贮藏期间硬度的影响，同时，通过测定贮藏期间脐橙果皮中与细胞壁结构相关的物质含量及酶活性的变化，揭示壳聚糖、纳米SiOx及两者复合处理保持脐橙果实硬度的机制。结果表明，1.5%壳聚糖、0.08%纳米SiOx及两者复合处理能显著抑制脐橙果实贮藏期间硬度的降低，复合处理的效果最佳。3 种处理均能延缓脐橙果皮中原果胶降解，抑制可溶性果胶含量的上升，刺激纤维素和木质素的生成，降低果胶甲酯酶、多聚半乳糖醛酸酶和纤维素酶的活性。说明壳聚糖、SiOx及两者复合处理通过调控脐橙果皮细胞壁结构相关物质的合成与降解，抑制相关酶活性，强化了脐橙果皮细胞壁的强度，抑制了果实硬度的下降。

Effects of Chitosan and SiOx Treatments on Firmness of Postharvest Navel Orange Fruits

The aim of this study was to investigate the effects of chitosan, SiOx and their combination on the firmness of
“Fengji” navel orange fruit during storage. The mechanism involved was explored by measuring the contents of compounds
and the enzyme activities related to the cell wall structure in peels. The results indicated that 1.5% chitosan and/or
0.08% SiOx could significantly delay the decrease of orange fruit firmness during storage. Meanwhile, the best effect was
achieved by the combined treatment. All three treatments could delay the degradation of pectin, suppress the increase
of soluble pectin, increase the contents of cellulose and lignin, and inhibit the activities of pectin methylesterase (PME),
polygalacturonase (PG) and cellulase. In conclusion, both the individual and combined treatments can reinforce the strength
of peel cell wall, inhibit the decrease of fruit firmness and maintain fruit quality by regulating the synthesis and degradation
of cell wall structural materials and inhibiting related enzyme activities.