大球盖菇干制过程香气变化规律及与关键酶促反应的关联性

Aroma Change and Its Relationship with Key Enzymatic Reactions in Drying Process of Stropharia rugosoannulata

采用顶空固相微萃取结合气相色谱-质谱联用技术对不同干制时间段的大球盖菇子实体中挥发性风味化合物进行分离、鉴定,探究其在55℃恒温热风干制过程中挥发性风味物质的变化规律。在整个干制过程中共鉴定出245种挥发性风味化合物,其中包括34种醛类化合物、29种酯类化合物、40种醇类化合物、37种酮类化合物、7种酸类化合物、24种烷烃类化合物、26种烯烃类化合物及48种其他类化合物;醛、酮、醇类化合物占比较大,三者含量之和占总含量的65.49%~89.30%,为大球盖菇中主要的挥发性物质。通过气味活度值热图分析结合偏最小二乘判别分析法,筛选出45种关键气味化合物,其中1-辛烯-3-酮始终是干制过程中气味贡献最大的化合物,整个干制过程中共有20种差异性化合物。综合分析得到大球盖菇干制过程香气变化规律:随着干制的进行,样品土腥味、青草气味逐渐减弱,干制后期呈现焦香、麦芽香等风味,但整个过程中蘑菇味、土腥味仍是大球盖菇的关键风味特征。对合成醛、酮、醇类化合物的主要代谢途径中的关键酶酶活进行测定,发现此类酶会受热激活,随干制的进行酶活整体呈现显著下降趋势,在干制终点几乎没有活性。代谢酶活性与对应化合物含量相关性分析表明,脂肪氧合酶与醛酮类化合物具有较强的正相关性,乙醇脱氢酶与醇类化合物具有较强的负相关性,这与大球盖菇干制过程中醛、酮、醇类化合物含量的动态变化趋势一致。

Headspace solid phase microextraction-gas chromatography-mass spectrometry technology was used to separate and identify the volatile flavor compounds in the fruiting bodies of Stropharia rugosoannulata at different drying periods,and the changes of volatile flavor compounds in the drying process under the condition of hot air drying at 55℃constant temperature was explored.A total of 245 volatile flavor compounds were identified in the whole drying process,including 34 aldehydes,29 esters,40 alcohols,37 ketones,7 acids,24 alkanes,26 olefins and 48 other compounds.Aldehydes,ketones and alcohols accounted for a relatively large proportion,and the sum of the three contents accounted for 65.49%-89.30%of the total content,which were the main volatile substances in Stropharia rugosoannulata.A total of 45 key odor compounds were screened out through the thermal analysis of odor activity value combined with partial least squares discriminant analysis.Among them,1-octene-3-ketone was always the compound with the largest contribution to the odor during the drying process,and there were 20 different compounds before and after the drying process.The comprehensive analysis showed that the aroma change law of Stropharia rugosoannulata during the drying process was as follows:with the drying process,the odors of soil and grass gradually weakened,and the flavors of coke and malt presented in the late drying process,but the mushroom flavor and soil odor were still the key flavor characteristics of Stropharia rugosoannulata during the whole process.Determination of key enzyme activities in the main metabolic pathways of aldehydes,ketones and alcohols,indicated that the enzyme would be activated by heat,and the enzyme activity showed a significant downward trend as a whole during the drying process.There was almost no activity at the end of the drying process.The correlation analysis between the metabolic enzyme activity and the corresponding compound content showed that lipoxygenase had a strong positive correlation with aldehydes and ketones,alcohol dehydrogenase had a strong negative correlation with alcohols.It was consistent with the dynamic change trend of aldehydes,ketones and alcohols during the drying process.