Fatty and amino acids composition of selected wild edible mushrooms of Bunyoro sub-region, Uganda

Abstract

For thousands of years, mushrooms have long been used for their health promoting properties. The aim of this study was to determine the fatty acids and amino acids contents in priority wild mushrooms: Termitomyces microcarpus, Termitomyces sp. (Bunyanaka), Termitomyces globulus, Termitomyces eurrhizus and Polyporus tenuiculus widely consumed in Bunyoro Sub-region, Uganda. The study revealed seventeen amino acids using pre-column derivatization with a phenylisothiocyanate followed by HPLC-UV-vis, and tryptophan using spectrophotometry. Fatty acids were determined by gas chromatography and detected by a flame ion detector. The essential amino acids ranged from 23.6% P. tenuiculus to 59.0% T. microcarpus of the total amino acids. Termitomyces sp. (Bunyanaka) and T. globulus were the most nutritious species based on essential amino acid indices. Generally, glutamic acid was high followed by phenylalanine, histidine, tryptophan and lysine concentrations, whereas threonine, valine, methionine, leucine, cysteine, arginine and tyrosine contents were either low or absent. T. eurrhizus and T. globulus were limited in leucine and valine, T. microcarpus in leucine and Termitomyces sp. (Bunyanaka) in isoleucine and valine. Unsaturated fatty acids predominated over saturated ones. Termitomyces sp. (Bunyanaka) and T. globulus had poor fatty acid profiles, rich in monounsaturated fatty acids (nervonic and eruic acids), had low PUFA:MUFA ratio and a PUFA+MUFA:SFA ratio greater than two. Docosahexaenoic (DHA) and a trans-fatty acid, elaidic were also identified in these mushroom species. This represents the first report on the occurrence of DHA in mushrooms. T. microcarpus had a fairly good profile, high in palmitoleic, e-linolenic, a- linolenic, palmitic and oleic acids. Stearic DHA, linoleic and eicosapentaenic acids were detected in small quantities. The odd carbon number fatty acids (heptadecanoic, heneicosanoic and cis-10-heptadecanoic) were also identified. These results serve as a basis to encourage the local communities to exploit the nutritive potentials of these mushrooms in order to reduce the burden of nutritional deficiencies. Key words : Amino acids, fatty acids, mushrooms