两个不同类型薄皮甜瓜品种成熟特性、香气成分及其相关酶活性分析

 【目的】比较两个品种薄皮甜瓜成熟特性、主要香气组分和含量以及香气合成相关酶活性。【方法】分别采用气相色谱仪和氧电极法检测薄皮甜瓜果实乙烯释放量及呼吸速率,利用气质联用(GC-MS)检测香气物质的种类和含量并测定香气合成关键酶活性。【结果】‘彩虹7号’乙烯和呼吸跃变期比‘日本甜宝’提前3 d,后者成熟果实可溶性固形物含量显著高于前者;成熟‘日本甜宝’果实中醇类和醛类含量均显著高于‘彩虹7号’,而总芳香物质和酯类含量差异不显著;‘彩虹7号’和‘日本甜宝’中总酯类与乙酸酯类物质含量分别在花后33 d 和35 d达到最大;‘日本甜宝’果皮和果肉中脂氧合酶(lipoxygenase, LOX)活性显著高于‘彩虹7号’,醇酰基转移酶(alcohol acyltransferase, AAT)活性则正好相反,两品种果实中醇脱氢酶(alcohol dehydrogenase, ADH)活性差异不显著,且果皮中芳香物质含量和酶活性均高于果肉。【结论】成熟时‘日本甜宝’中较高的醇、醛含量是其果实清香的重要原因,酯类与各香气成分相互之间构成比例的差异可能是导致薄皮甜瓜果实整体香气不同的原因,LOX、ADH和AAT协同作用影响果实的香气类型。

Analysis of Ripening Characteristics,Aroma Components and Aroma-Related Enzymes in Oriental Sweet Melons(Cucumis meld var.makuwa Makino)

【Objective】Comparison on ripening characteristics, main aroma compounds and aroma-related enzymes activities between two cultivars of oriental sweet melons were conducted.【Method】Gas chromatograph and oxygen electrode method were used to detect ethylene production and respiration rate, respectively. Varieties and content of aroma compounds were measured by gas chromatograph-mass spectrometer(GC-MS), whilst aroma-related enzymes activities were also determined.【Result】 Climacterics of ethylene and respiration of ‘Caihong7’ were 3 days earlier than ‘Japanese Tianbao’. The soluble solids contents of mature ‘Japanese Tianbao’ were significantly higher than that of ‘Caihong7’. The contents of alcohols and aldehydes were higher of ripening ‘Japanese Tianbao’ were higher than that of ‘Caihong7’ markedly, while the differences on content of total aroma volatiles and esters were not significant. The content of total and acetate esters reached maximum value on day 33 and 35 after anthesis in ‘Caihong7’ and ‘Japanese Tianbao’, respectively. Activities of LOX in flesh and peel of ‘Japanese Tianbao’ were significantly higher than in ‘Caihong7’, whereas AAT activities followed the opposite trend and no significant differences in ADH activities were observed in both cultivars. The content of aroma compounds and enzyme activities were higher in peel than in flesh of both cultivars. 【Conclusion】Higher contents of alcohols and aldehydes in mature ‘Japanese Tianbao’ considered to be important contributors to its cucumber-like flavor. The different components proportion of aroma compounds might be the reason for causing different types of fragrance between both cultivars. LOX, ADH and AAT had interaction effects on fragrance types.