Micoproteínas de macrofungos obtidas em cultivo em estado sólido: avaliação do enriquecimento nutricional e compostos bioativos

Abstract

The population growth and depletion of natural resources demand research into new alternatives for the supply of protein foods. Alternative sources of proteins, such as those derived from microorganisms, can help solve this problem. In this study, Agaricus blazei, Auricularia fuscosuccinea and Pleurotus albidus mycoproteins were produced in solid-state cultivation (SSC) using vegetable raw materials such as grains (brown rice, corn, wheat) or bagasse (brewer spent grain, grape marc) in the cultivation medium. The colonized material was dried and milled to obtain mycoproteins flours which were analyzed for mycelial biomass content, nutritional composition, physical and physicochemical characteristics, bioactive secondary compounds (ergosterol, ergothioneine and lovastatin), biological activity in vitro (antioxidant and α-glicosidase, α-amilase and pancreatic lipase enzymatic inhibition) and compared with the respective control flour. The results demonstrated that in the production of P. albidus mycoproteins, mycelial growth was observed in all the raw materials used, being determined the highest values of ergosterol (0.60 mg.g-1) and fungal biomass (183 mg.g -1) in flours obtained from wheat grains myceliated by this macrofungi. In the evaluation of the nutritional composition, regarding the proteins and total amino acids, the most relevant results were observed in mycoproteins of P. albidus. In flour obtained from wheat grains and brewer spent grain myceliated by P. albidus, the percentage of protein enrichment relative to the control were 46 and 42%, respectively; and increase in total amino acid content compared to control were 17.7 and 20.2%, respectively. As for the phenolic compounds and antioxidant activity, in general, the highest values were determined in the A. fuscosuccinea mycoproteins. In these aspects, it is possible to highlight the flour obtained from corn grain myceliated by A. fuscosuccinea, in which the phenolic content was 29 times higher than the control, and the scavenging capacities of the radicals DPPH· and ABTS·+ were 10 and 55 times higher than control, respectively. In the investigation of the secondary compounds, the presence of ergothioneine was identified particularly in the P. albidus mycoproteins, as in the flour obtained from wheat grain myceliated by the fungus in which the concentration of 26.01 μg.100 g -1 of sample was determined. The highest concentrations of lovastatin were determined in A. fuscosuccinea mycoproteins flour produced in wheat grain (0.660 μg.100 g -1) and in brewer spent grain (1.170 μg.100 g -1), and also in the P. albidus mycoprotein produced in grape marc (0.883 μg.100 g -1). A. blazei and P. albidus mycoproteins were the most effective inhibitors of the α-glycosidase enzyme (at least 78.4% inhibition in the in vitro assay). The highest inhibition of pancreatic lipase in vitro (74.5%) was evidenced in the P. albidus mycoprotein produced in wheat grain. Finally, P. albidus mycoprotein flour produced in brewer spent grain was used to nutritionally enrich the formulation of a cookie. Total replacement of refined wheat flour by mycoprotein flour resulted in a product with higher values of protein (11.60 g.100 g -1), of total dietary fiber (32.35 g.100 g -1), of antioxidant activity (50.4% in DPPH assay) and α- glucosidase inhibition (74.9%). In conclusion, macrofungi mycoprotein production is a promising strategy for nutritional enrichment and the production of bioactive compounds, with potential use as a functional ingredient in food or as an additive in animal nutrition. [resumo fornecido pelo autor]