基于细胞壁特性改变的猕猴桃果实软化机制研究

Study on the Softening Mechanism of Kiwifruit Fruit Based on Changes in Cell Wall Properties

为探究采后猕猴桃果实软化与细胞壁特性的作用机制,以采后不同时期的陇南猕猴桃为研究对象,分析采后0 d(硬熟期-T1)和采后20 ℃、45%RH条件下熟化3 d(软化初期-T2)2个时期可滴定酸(TAC)、呼吸速率、可溶性固形物(SSC)、果实细胞微观结构、粗细胞壁、纤维素、半纤维素、果胶(WSP、CSP、ISP)含量、细胞壁多糖分子质量及单糖组成与果实硬度的关系。结果表明:与T1时期相比,T2时期果实硬度和可滴定酸出现显著性降低(P<0.05),而可溶性固形物、呼吸速率出现显著性升高(P<0.05);对比细胞微观结构发现,果实细胞壁在T2时期厚度变薄,粗细胞壁、纤维素、半纤维素、果胶(WSP、CSP、ISP)含量、细胞壁多糖分子质量均出现显著性降低(P<0.05);细胞壁结构单糖中阿拉伯糖含量降低最为显著,其次是葡萄糖。综上,细胞壁的结构和组分的改变是果实软化的内在因素,通过促进或抑制细胞壁的降解过程,可有效改善猕猴桃的贮藏和加工品质,研究结果为猕猴桃果实采后贮藏保鲜提供了理论依据。

In order to investigate the mechanism of postharvest kiwifruit fruit softening and cell wall properties,this experiment was conducted on Longnan kiwifruit at different postharvest periods to analyze the relationships between titratable acid (TAC),respiration rate,soluble solids (SSC),fruit microstructure,crude cell wall,cellulose,hemicellulose,pectin (WSP,CSP,ISP) content,cell wall polysaccharide molecular weight and monosaccharide composition and fruit hardness at 0 days postharvest (hard ripening-T1) and 3 days postharvest (early softening-T2) at 20 ℃ and 45% RH.The results showed that fruit hardness and titratable acid decreased significantly (P<0.05),while soluble solids and respiration rate increased significantly (P<0.05) in T2 compared with T1.Comparing the cell microstructure,it was found that the thickness of fruit cell wall became thinner at T2 stage,and crude cell wall,cellulose,hemu-cellulose,pectin (WSP,CSP,ISP) content and molecular weight of cell wall polysaccharides were decreased significantly (P<0.05);the most significant decrease in cell wall structural monosaccharides was found in arabinose content,followed by glucose.In conclusion,changes in the structure and components of the cell wall are intrinsic to fruit softening,and by promoting or inhibiting the degradation process of the cell wall,the storage and processing quality of kiwifruit can be effectively improved,and the results of this study provide a theoretical basis for postharvest storage and preservation of kiwifruit fruit.