Distribution of Nutrients, Polyphenols and Antioxidant Activities in the Pilei and Stipes of Some Commonly Consumed Edible Mushrooms in Nigeria

The distribution of nutrients, polyphenols and antioxidant activities between the pilei (caps) and stipes (stalks) of three commonly consumed edible mushrooms in Nigeria namely: Termitomyces robustus [pilei (TRC) and stipes (TRS)], Coprinus sp [pilei (CSC) and stipes (CSS)] and Volvariella esculenta [pilei (VEC) and stipes (VES)] were evaluated. The pilei were separated from the stipes and their proximate composition was determined. Thereafter, their antioxidant properties as typified by their total phenol content, reducing power, DPPH free radical scavenging ability and inhibition of lipid peroxidation in vitro were determined. The pilei of the mushrooms had significantly higher (p < 0.05) protein, fat and ash content than the stipes, while the crude fibre was significantly higher (p < 0.05) in the stipes than the pilei. However, no significant difference (p > 0.05) exists between the total phenol content of the pilei [VEC (2.1 mg/g), TRC (2.5 mg/g), CSC (2.3 mg/g)] and the stipes [VES (2.0 mg/g), TRS (2.3 mg/g), CSS (1.8 mg/g)]. Nevertheless, polyphenol extracts from the stipes had a significantly (p < 0.05) higher free radical scavenging ability and reducing power than those from the pilei. Furthermore, the polyphenol extracts inhibited lipid peroxidation in the cow’s brain homogenates in a dose dependent manner; however, no significant difference (p > 0.05) exists in the inhibitory effect of the polyphenols at higher concentrations. Therefore, pilei of the mushrooms had more protein, ash and fat content; while there was no significant difference in the polyphenol distribution between the pilei and stipes; conversely the polyphenols from the stipes had higher antioxidant activity (except inhibition of lipid peroxidation) than that of the pilei.