Shiitake mushrooms (Lentinus edodes) form a great source of protein; however, the effect of enzymatic hydrolysis to improve its flavor has not yet been investigated. To explore the effects of different protease treatments on protein degradation and flavor compounds of shiitake mushrooms, papain, neutral protease, and flavourzyme were selected for the hydrolysis of shiitake mushrooms. Proteolysis index, Trichloroacetic acid-nitrogen soluble index, and protein content were estimated to evaluate protein degradation. Flavor amino acids and volatile components of the hydrolysate were also analyzed. Results showed flavourzyme has an advantage over the others in promoting protein degradation and improving flavor. Compared to single-enzyme treatment, a combination treatment with three enzymes, at 1:1:1 ratio, was found to perform greater protein hydrolysis. After protease-mediated hydrolysis, the variety and content of flavor substances (free amino acids and eight-carbon compounds) in L. edodes increased. We concluded that protease treatment is an effective method for improving the quality and flavor of L. edodes.

To explore the effects of fermentation on the umami taste substances of shiitake mushrooms (Lentinus edodes), the umami substances of fermented shiitake mushrooms using different microorganism species were investigated. Saccharomyces cerevisiae, Aspergillus oryzae, Aspergillus niger and Lactobacillus plantarum were selected to ferment the pileus and stipe of shiitake mushrooms, and the umami substances in the fermentation liquid were analyzed and compared. The contents of free amino acids and flavor nucleotides were measured, and the taste activity value (TAV) and equivalent umami concentration (EUC) were calculated to evaluate the taste of fermentation. The results showed that acidity as well as the content of free amino acids and flavor nucleotides in the fermentation broth increased throughout the fermentation process. The EUC values of the fermentation broths ranged from 9.95 to 34.58 g monosodium glutamate (MSG)/100 g, and TAVs were greater than 1. According to our analysis, Lactobacillus plantarum was the best species for fermentation providing the strongest umami flavor.

Abstract To explore the effects of fermentation on the umami taste substances of shiitake mushrooms (Lentinus edodes), the umami substances of fermented shiitake mushrooms using different microorganism species were investigated. Saccharomyces cerevisiae, Aspergillus oryzae, Aspergillus niger and Lactobacillus plantarum were selected to ferment the pileus and stipe of shiitake mushrooms, and the umami substances in the fermentation liquid were analyzed and compared. The contents of free amino acids and flavor nucleotides were measured, and the taste activity value (TAV) and equivalent umami concentration (EUC) were calculated to evaluate the taste of fermentation. The results showed that acidity as well as the content of free amino acids and flavor nucleotides in the fermentation broth increased throughout the fermentation process. The EUC values of the fermentation broths ranged from 9.95 and 34.58 g monosodium glutamate (MSG)/100 g, and TAVs were greater than 1. According to our analysis, Lactobacillus plantarum was the best species for fermentation providing the strongest umami flavor.

Shiitake mushroom (Lentinus edodes) is the second most-widely-consumed edible fungi with strong flavor and unique taste. To study the effects of Lactiplantibacillus plantarum fermentation on umami compounds in shiitake mushrooms, the levels of taste-imparting compounds were analyzed, including organic acids, free amino acids, and 5'-nucleotides during fermentation. The contents of all umami compounds except for succinic acid and fumaric acid were improved with increasing fermentation time; broths obtained at each fermentation stage formed clear clusters upon subjecting the electronic tongue data to principal component and discriminant function analyses. Compounds that predominantly contributed to important umami were identified. Among the 30 umami compounds investigated, 11 compounds were considered to be predominantly responsible for the different taste characteristics of shiitake mushroom broths at various stages of fermentation. Taken together, L. plantarum fermentation improved the contents of umami taste compounds in shiitake mushroom.

目的:探究植物乳杆菌发酵对香菇不同部位风味物质的影响.方法:以香菇盖和香菇柄发酵液为原料,以香菇发酵液的等鲜浓度(EUC)为响应值,分别考察发酵时间、菌液接种量、粉末添加量和发酵温度4个因素对发酵的影响;通过Box-Behnken Design(BBD)响应面分析优化植物乳杆菌发酵香菇盖和香菇柄的最佳工艺条件.结果:植物乳杆菌发酵香菇盖的最优工艺条件为发酵时间4 d,接种量4.5％,粉末量1.5 g,发酵温度40℃;植物乳杆菌发酵香菇柄的最优工艺条件为发酵时间3 d,接种量4.2％,粉末量1.5 g,发酵温度30℃.在此条件下香菇盖和香菇柄发酵液的EUC值分别为84.61 gMSG/100 g和32.02 gMSG/100 g,与预测值84.09 gMSG/100 g和32.38 gMSG/100 g相近.结论:本试验从多角度优化植物乳杆菌发酵香菇工艺,为香菇的进一步加工提供理论基础.