外源乙烯对冷藏桃果实香气物质合成的调控

Aroma Volatiles Biosynthesis and Relative Enzyme Activities Regulated by Exogenous Ethylene in Peach Fruits Stored at Low Temperature

为了探讨外源乙烯对冷藏过程中‘大久保’桃果实香气合成的调控,以常温贮藏桃(CK1)和0℃贮藏桃(CK2)为对照,在低温贮藏期间外源乙烯处理(T)对桃果实中芳香成分的释放及香气合成相关酶脂氧合酶(LOX)、乙醇脱氢酶(ADH)和乙醇酰基转移酶(AAT)活性的影响进行研究。结果表明:在测得的29种挥发性香气中,有19种成分的合成受到低温抑制,含量降低,在外源乙烯的诱导下除了薄荷醇外,其余18种成分含量均升高;在10种受低温诱导而含量增加的成分中,有4种同时被外源乙烯诱导,而其余6种成分则受到外源乙烯的抑制含量降低。低温阻遏薄荷醇的合成,因此只在常温条件下检测到。低温冷藏导致花香型香气酯类物质代谢发生障碍,果实品质下降;而施加外源乙烯能促进特征香气芳樟醇和γ-癸内酯的合成,抑制己醛、反-2-己烯醛和苯甲醛的释放,青草型与花香型香气比值降低,从而有利于果实品质的改善。LOX活性受到乙烯的抑制而降低,而ADH和AAT则受乙烯的诱导活性升高,相应的6-C醛类物质在外源乙烯处理的桃果实中含量降低。

In order to explore the regulation of exogenous ethylene on biosynthesis of aroma volatiles in peach during cold （0 ℃ ） storage, the release of aroma components as well as the changes of LOX, ADH and AAT activity closely related biosynthesis of aroma volatiles were investigated. The peaches stored at ambient temperature and 0 ℃ respectively served as the control 1 and control 2. The results showed that the syntheses of 19 components were inhibited by low temperature and their contents decreased. However the all components, except for menthol, were induced by exogenous ethylene and increased. The other 10 components were induced by low-temperature and increased in the cold storage. Four components of the 10 were induced by exogenous ethylene simultaneously, while the rest six were inhibited by exogenous ethylene. Low temperature repressed the synthesis of menthol, thus it was detected only under room temperature condition. Low-temperature storage resulted in obstacles of floral aroma esters metabolism, and lowered the fruit quality, while exogenous ethylene could promote the biosynthesis of the characteristic aroma linalool and γ-decalaetone, inhibit hexanal, trans-2-hexenoic aldehyde and benzaldehyde release, and reduced the radio of the grassy flavor and floral flavor, so that the fruit quality was improved by exogenous ethylene. LOX activity was inhibited by exogenous ethylene, but the activity of ADH and AAT were elevated by exogenous ethylene, leading to reduction of the content of 6-C aldehydes accordingly.