Vietnam's agri-food sector produces 1.64 million tons of byproducts yearly and contributes almost 26% of the country's GDP in 2023. A very small portion of this waste was turned into compost, with the majority being disposed of as waste in the environment. However, there has not been much done in the way of research or technical applications to utilize this residue up to this point. Hence, this study investigated the effect of solid-state fermentation with Pleurotus citrinopileatus mycelia on polysaccharide (PS) and protein contents, antioxidant properties, probiotic growth stimulation, pathogenic inhibition, and bio-physicochemical properties of extracts from culture medium before and after fermentation was investigated. The findings indicated that when cassava (CASS) residue and okara are mixed in a 1:1 ratio, the mycelium develops swiftly uniform, even white, very thick, and high density. The total protein, ash, and PS contents from this fermented mixture were raised by 65.12%, 70%, and 57.24%, respectively. The PS extract inhibited the growth of Escherichia coli and Staphylococcus aureus with sterile ring diameters of 3.47 ± 0.38 and 3.06 ± 0.27 cm, respectively; stimulated the growth of Lactiplantibacillus plantarum with a colony density of 9.34 logCFU/ml after 24 hours of culture; and increased antioxidant capacity with IC50 = 3,287.62 g/ml. Heavy metals content, bacteria, yeasts, and mold levels were all lower than the allowable thresholds as recommended for animal feed purposes. The results show that P. citrinopileatus mycelium can ferment CASS residue and okara to produce a safe and nutritious source of animal feed supplements. This offers a viable approach for enhancing the added value of agricultural residue. Thus, more research is required to assess the financial viability of using fermented substrates produced by oyster mycelium as an additional feed source for animals. Researchers can also concentrate on conducting additional studies on the safety, use, and biological activity of the isolated PS fractions in the functional food sector.
Key words: agricultural residues, antioxidant, cassava residue, okara, P. citrinopileatus solid-state fermentation.
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