温度和乙烯处理对番荔枝软熟过程中多糖代谢的影响

摘要

以AP(African Pride)番荔枝冬季果为试材,研究不同温度、乙烯利处理下,番荔枝果实淀粉、可溶性糖、蔗糖等糖类以及果胶含量和细胞壁代谢相关酶(多聚半乳糖醛酸酶、纤维素酶、果胶甲酯酶)活性的变化,以期从多糖代谢角度探讨温度和乙烯对番荔枝冬季果软熟的影响.结果表明:低温(20℃)可延缓淀粉向可溶性糖的转化,高温(32℃)可促进淀粉向可溶性糖的转化,而28 ℃下番荔枝软熟最快.28、32℃下果实果皮变硬可能与果皮中原果胶的合成有一定关系.果实的软化与果肉中的原果胶降解有关,但和可溶性果胶含量上升无必然联系.温度和乙烯对酶活性均有不同程度影响,其中Eth-28℃处理对酶活性诱导最显著.Cx和PG活性的变化与果实软化最相关,而PME在果实软化中可能不起关键作用.%African Pride(AP) winter fruits were chosen as the materials.In order to explore the effects of temperature and ethylene on atemoya winter fruit ripening and softening from the perspective of polysaccharide metabolism,starch,total soluble sugars,sucrose contents in pulp,protopectin and soluble pectin in the pericarp and pulp were determined,meanwhile the cell wall metabolism related enzymes(PG,Cx,PME) activities in the pericarp and pulp were analyzed.The results showed that low temperature(20 ℃) inhibited the conversion of starch to soluble sugars,and high temperature(32 ℃) promoted starch degradation,whereas under 28 ℃,fruits softened the fastest.The pericarp was hardened under 28 ℃ and 32 ℃,which might have relationship with the protopectin synthesis.The softening of the fruits might be associated with the protopectin degradation in the pulp,but no positive connection with soluble pectin contents increased.Both temperature and ethylene had different degree influence on PME,PG and Cx activities,but 28 ℃ treatment had more significant inducement on enzymes activities than other treatments.The activities of Cx and PG changes were tightly associated with fruit softening,whereas PME might not be a key role in fruit softening.