Effects of drying methods on non-volatile taste components of Stropharia rugoso-annulata mushrooms

In this study, the pileus and stipe of Stropharia rugoso-annulata were separately dehydrated using natural air drying (NAD), hot air drying (HAD) and vacuum freeze drying (VFD), the proximate composition and non-volatile compounds (soluble sugars, organic acids, free amino acids and 5′-nucleotides) were investigated. We found that the contents of free amino acids (37.21–51.07 mg/g) and 5′-nucleotides (18.33–22.76 mg/g) in pileus were higher than those of stipe. The contents of MSG-like amino acids (3.61–11.70 mg/g) and flavor 5′-nucleotides (5.47–5.94 mg/g) in pileus were also higher than those of stipe. The dried S. rugoso-annulata treated with VFD had the highest levels of soluble sugars, organic acids, free amino acids and 5′-nucleotides. We found that NAD and HAD had medium levels of MSG-like amino acids (7.95–11.7 mg/g) and VFD had low levels of MSG-like amino acids (3.16–3.61 mg/g). Moreover, HAD had the highest level of equivalent umami concentration (EUC) value (784.05 g MSG/100 g). Our results suggested that VFD was better to preserve the non-volatile compounds in S. rugoso-annulata, but HAD would be a potential method to produce umami concentration of dried S. rugoso-annulata.