Nutritional Composition of Wild Edible Mushrooms Growing in Kenya and their Utilization in Food Product Development

Abstract

Mushrooms, a group of macro-fungi, have been used as food for centuries all over the world because of their characteristic texture and flavor. They are documented as being good source of nutrients and bioactive compounds beneficial to the human body. In spite of this, consumption of wild mushrooms in Kenya is low. This research aimed at determination of nutritional chemical composition and phytochemical compounds of wild edible mushroom found in selected areas in Kenya and utilization of the mushrooms in product development. Two commercially grown and ten wild edible mushrooms species were collected from coast, central and western parts of Kenya. They were analyzed for nutrients according to standard procedures. All the analysis was done in triplicate. Proximate analysis showed high levels of nutrients: lipids, 1.6-10.3 %; insoluble fiber 4.5-16.3 %; ash 6.6-21.8%; protein 16.6-35.9 % and soluble carbohydrates 37.5-63.3 %. Mineral analysis showed presence of calcium, sodium, copper, manganese, zinc, potassium, phosphorus, magnesium and iron. Potassium was found to be present in the highest proportion in most of the species (202 -4140 mg/100 g, dwb) and iron most abundant trace element (4.2-42.1 mg/100 g, dwb). Water soluble vitamins B2, Folate and ascorbic acid were detected in all the mushrooms at 0.1-6.4; 0-0.8 and 0.1-1.2, mg/100 g (dwb) respectively. Phytochemical compounds screening indicated presence of saponins, polyphenols and terpenoids. Total polyphenols values ranged 210.5-1614.1 mg/100g, dwb and flavonoids 214.2-1695.4 mg, Quercetin Equivalent (QE)/100 g dwb. The results showed a positive relationship between both total polyphenols (TP) and total xvii flavonoids (TF) with the radical scavenging activity (RSA). Mushrooms with high TP/TF had high RSA values. The correlation coefficient between polyphenols and RSA was 0.8. High RSA is a desirable property. Mushroom flour was used in development of noodles, soup and biscuits. Subsequently consumer preference evaluation was done. Noodles with 25 % oyster and soup with 2.5 % oruka mushroom flour received highest consumer preference rating. The research showed that all mushrooms are rich in nutrients and phytochemical compounds which are necessary for a healthy body. It also showed that all types of edible mushrooms can be used in formulation of value-added products.