冷藏杏果LOX代谢途径香气形成生化机制研究

. Apricot is the characteristics fruit in Xinjiang, and the output of the apricot in Xinjiang was the most in China. Because of the special geographical environment and climate in Xinjiang, the colour and lustre is gorgeous, fleshy delicate, also the aroma was unique. The storage period and shelf life of the apricot was very short at room temperature. Low temperature can reduce the respiration intensity of the fruit and inhibit the senescence and disease, so, the apricot storage period can be extended. After long-term cold storage, the aroma of the apricot fruit, the edible value and economic value were reduced seriously. The LOX pathway is an important biosynthetic pathway of apricot fruit aroma components. With apricot (Saimaiti) as materials, sampling the apricot stored at 0℃,using SPME-GC-MS/MS to analyze the aroma components, to ensure the main aroma components of the apricot. The composition and content of fatty acid of aroma substance would be determined.The activity of the key enzyme in LOX pathy would be determined, the gene of key enzyme would be quantitative analysis by qPCR. The Biochemical mechanism and changes of LOX pathway aroma formation during cold storage would be studied, to fully understand the reason of the reduction of the aromaduring the cold storage. The research results would provide the theory reference for the fruit aroma change of the storage, would have an important significance for promoting the development of Xinjiang apricot industry.

杏是新疆特色水果之一，杏果实采后通过冷藏方式延长其贮藏期和货架期。杏果实冷藏期间风味物质丧失，严重影响了果实的商品质量和食用价值。LOX途径是杏果实香气成分的重要生物合成途径。研究以新疆商品性和食用性较好的主栽杏品种赛买提杏为实验材料， 0 ℃ 贮藏期间取样， 采用SPME-GC-MS/MS 对香气成分进行分析，主成分分析确定主体香气成分；GC检测香气前体物质脂肪酸的组成和含量；测定LOX 途径中关键酶活力；qPCR 对关键酶的基因进行定量分析，研究杏果实冷藏过程中基于LOX途径香气形成及变化的生化机制。通过对LOX 途径香气形成及变化生化研究，充分了解杏果实冷藏中香气丧失的原因。研究成果为冷藏中杏果实风味变化调控提供理论参考，对促进新疆杏产业的发展具有重要意义。

本课题以赛买提杏为原料，基于脂肪酸代谢途径研究冷藏过程中杏果实香气物质、香气前体物质及脂肪酸代谢相关酶活和基因表达的变化，进而阐明低温影响杏果实香气物质合成分子机制。.通过研究，获得的主要研究结果有：（1）研究了0℃和4℃冷藏温度及常温贮藏温度25℃对杏果品质的影响。4℃贮藏杏果的腐烂率和褐变指数均高于0℃，品质低于0℃，因此，更适合于杏果采后冷藏的温度是0℃。（2）测定了3种温度下贮藏杏果香气成分的变化， 0℃和4℃贮藏杏果香气数量和总量显著低于常温贮藏杏果。呼吸跃变期，常温贮藏和冷藏杏果的香气种类和含量均显著增加，乙烯释放量的增加对杏果香气的形成有重要影响。（3）在贮藏过程中，0℃和4℃贮藏杏果LOX代谢途径中的LOX酶、醇酰基转移酶（AAT）的活性在呼吸跃变期(21天)达到最大，氢过氧化物裂解酶（HPL）活性在呼吸跃变前达到最大、乙醇脱氢酶（ADH）活性则持续上升。（4）贮藏过程中，杏果LOX基因和AAT基因表达量的变化与LOX和AAT酶活性的变化具有较好的一致性，但与杏果醛类和酯类香气含量的变化一致性较差。