Contents of 5’-GMP, free amino acids and lentinic acid among the different cultivars of shiitake mushroom

(Lentinula edodes (Berk.) Pegler)

Abstract

　In this study, 39 cultivars of shiitake mushroom (Lentinula edodes (Berk.) Pegler) cultivated on solid media under the same conditions were analyzed for flavor components (umami) conferred by nucleotide,amino acids or peptides, such as guanosine 5’-monophosphate (5’-GMP), free amino acids and lentinic acid. The highest pileus 5’-GMP concentration (151.8 mg/100 g dry weight (d.w.)) was approximately 15 times that found in pileuses of the cultivar with the lowest 5’-GMP concentration (10.1 mg/100 g d.w.). Similarly, the highest stipe 5’-GMP concentration (60.2 mg/100 g d.w.) was approximately 14 times that found in the stipes of the cultivar with the lowest concentration (4.4 mg/100 g d.w.). Compared to the cultivar with the second highest 5’-GMP levels, 5’-GMP production was 1.5 times higher in the cultivar with the highest 5’-GMP levels. So this cultivar was specially prominent in all 37 cultivars analyzed. In addition, cultivars with high pileus 5’-GMP concentrations tended to have high stipe 5’-GMP concentrations. Wild shiitake cultivars had low 5’-GMP production ability, but 5’-GMP was high in shiitake cultivars considered suitable for log cultivation. The amounts of free amino acids in the pileus and stipe varied markedly between different cultivars. The lowest level of glutamic acid a typical umami compound in the pileus (66.0 mg/100 g d.w.) was 7.6 times lower than the highest level measured in the pileus of most cultivars (500.1 mg/100 g d.w.). Glutamic acid production in the pileus and stipe were markedly higher in wild cultivars compared to cultivars grown on sawdust substrate or on logs. Lentinic acid was the second most common flavor component to glutamine in the pileus and stipe, with a three-fold difference observed between the minimum and maximum pileus concentrations (i.e. 531.0 and 1635.9 mg/100 g d.w., respectively).