Effect of postharvest storage at ambient temperature on the micronutrients, phytochemicals and phenolic profile of the sclerotia of king tuber mushroom (Pleurotus tuber-regium)

摘要

King tuber mushroom (Pleurotus tuber-regium (Fr.) Sing.) is found in various continents of the world such as Africa, Asia and Australia, where it grows naturally on decaying wood in the forest. The king tuber mushroom is a macro-fungus with edible sclerotia that are used as food, herbal medicine and food additives such as bulking and flavoring agents. Its unique flavor and health benefits can be attributed to the presence of micronutrients and phytochemicals such as phenolics. The mushroom provides agood source of income to local farmers and traders, who usually store them for long duration under ambient temperature after harvest. This study examined the effect of postharvest storage at ambient temperature on the micronutrients and phytochemicals that are present in the king tuber mushroom. Micronutrients such as iron, zinc magnesium and calcium were high in the freshly harvested mushroom, but showed decline in concentrations during the postharvest storage period of 16 weeks. Phytochemicals such as tannins, phenols, alkaloids, flavonoids and saponins showed marked increase in concentrations within the postharvest storage period except for phenols, in which decrease was observed. The phenolic profile of the mushroom showed the presence of 41 constituents, which included cathechin with antioxidant activity, carvacrol with antimicrobial and antioxidant activities, salicyclic acid, vanillic acid, ferulic acid, kaempferol, gallic acid and quercetin. These phenolics showed decrease in concentrations with postharvest storage. The freshly harvested mushroom is very rich in micronutrients and phytochemicals and can be used as food, food additive and herbal medicine, however, some of the micronutrients and phenolics decreased with long postharvest storage period.