Abstract

Volvariella volvacea, also known as straw mushroom or paddy straw mushroom is a tropical and subtropical tasty edible mushroom, characterized with the difficulty to store after harvest due to an endogenous enzymatic phenomenon of self digestion (autolysis). The mushroom has been shown to contain complex enzymatic systems which are both endogenous and exogenous in activity. The aim of this study was to assess biochemically the endogenous enzymes responsible for the mushroom self-digestion that gives rise to its short shelf-life. Enzymatic assay method of Cleland was used to determine possible endogenous enzymes in the mushroom. The study revealed eight (8) enzymes; namely: Glucose-oxidase, Hexose-oxidase, Glucotransferase, Lipase tributyrase, Tannase, Cellulase, Decarboxylase and Phosphoglucose-isomerase. These are oxidative, lytic and hydrolytic enzyme groups. The implication is that if V. volvacea grows on a substrate made of lignin, its exogenous enzymes will secrete oxidative enzymes. However, as the mushroom attempts to grow in the presence of its endogenous hydrolytic enzymes and while in the struggle to grow, it loses its strength, becomes weak, soft, decomposes and consequently dies, because it lacks the ability to synthesize phenol-oxidizing and lignin transforming enzymes which are supposed to transform the lignin material to substrates for its benefits. Therefore, this study satisfies the search that the presence of endogenous enzymes as mentioned above in V. volvacea are truly responsible for the self-digestion (autolysis) that gives rise to the short shelf life of the mushroom.