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研究了 2 0℃、相对湿度 80 %～ 90 %条件下黄花梨果实采后软化的生理生化变化。结果表明 ,黄花梨属于呼吸跃变型果实 ,采后果肉硬度逐渐下降而出汁率逐渐增加。采后 5d内淀粉酶活性增加 2 .9倍而淀粉含量下降 72 .80 % ,之后淀粉酶活性和淀粉含量逐渐下降。采后原果胶和纤维素含量下降而可溶性果胶含量增加 ,且果肉硬度同原果胶含量和纤维素含量都呈极显著正相关 (P <0 .0 1)。采后 5d内 ,多聚半乳糖醛酸酶 (PG)和纤维素酶活性变化不大 ,之后迅速上升 ,到采后 15d达到酶活性高峰 ,分别为采收时的 3.0倍和 7.9倍 ,之后酶活性逐渐下降。因而认为 ,黄花梨采后 5d内果肉软化 ,主要是淀粉酶活性的快速上升催化淀粉的快速水解造成的 ,并为呼吸跃变准备能源物质 ;之后果肉软化是由PG、纤维素酶作用引起果胶质、纤维素等细胞壁组分降解所致。
The physiological and biochemical changes of Huanghua pear fruit at 20 ℃ and relative humidity of 80% ~ 90% were studied. The results showed that P. hupehensis belonged to the climacteric fruit of respiration, and the fruit firmness gradually decreased and the juice yield increased gradually. After 5d, the amylase activity increased by 2.9 times and the starch content decreased by 72.80%, then the amylase activity and starch content decreased gradually. The content of pectin and cellulose decreased and the content of soluble pectin increased after harvest, and the fruit firmness had extremely significant positive correlation with the original pectin content and cellulose content (P <0.01). Within 5 days after harvest, the activities of polygalacturonase (PG) and cellulase did not change much, then increased rapidly and reached the peak of enzyme activity 15 days after harvest, 3.0 times and 7.9 times harvested respectively Enzyme activity gradually decreased. Therefore, the flesh softening of Huanghua pear within 5 days after harvest was mainly caused by the rapid increase of amylase activity caused by the rapid hydrolysis of catalytic starch and the preparation of energy substances for respiration. Afterwards, flesh softening was caused by the action of PG and cellulase Glial, cellulose and other cell wall components caused by degradation.