Nutritional improvement of wheat grains and soybeans by solid-state fermentation with Pleurotus ostreatus mycelium

Abstract

The nutritional quality of plant-based substrates can be improved through fungi-based fermentation. This study evaluates changes in the nutritional and non-nutritional composition of food substrates biotransformed with the edible mushroom Pleurotus ostreatus over time. The mycelium was cultivated on wheat grains or soybeans using solid-state fermentation, and the myceliated substrates were analyzed. Mycelium grows on both substrates but at a higher rate in wheat grains. Protein and phosphorus contents increase linearly with mycelial growth in both substrates, with final values up to 53 % and 36 % higher than the initial contents in wheat, while carbohydrates decrease linearly. Phytic acid shows a linear decrease, coinciding with 3- and 2-fold increases in wheat and soybean's acid-soluble/total phosphorous ratio. Phenolic content and antioxidant capacity increase in both myceliated substrates, fitting logistic growth models, with 7.8- and 4.8-fold increases in wheat. This study shows that solid-state fermentation with P. ostreatus can be applied to wheat and soybeans to enhance their content of valuable nutrients and bioactive compounds and to decrease their antinutrient content. Changes in both nutritional and non-nutritional composition are linked to the extent of mycelial growth, which can be reliably evaluated by simply measuring the percentage of substrate consumption.