Safety and suitability of using Aspergillus oryzae for the production of legume-based meat substitutes

Abstract

Abstract

The growing world population is increasing the need for high-quality, non-animal protein sources. This literature review presents an overview of research to discuss the safety and suitability of fermentation of A. oryzae to produce legume-based meat substitutes. Legumes contain antinutritive molecules, do not contain sufficient amounts of indispensable amino acids (IAAs), and their taste and texture differs greatly from meat. Fermentation of legumes with Aspergillus oryzae could provide a solution to these challenges. It is shown that A. oryzae does produce kojic acid (a mycotoxin), but at concentrations safe for human consumption. Multiple sources are presented to explore the genetic similarity between A. oryzae and aflatoxin B1 (AFB1)-producing A. flavus. A. oryzae does not produce AFB1 although the gene cluster is preserved on its genome (133 000 SNPs compared to A. flavus genome). Research is presented that suggests inhibition of AshA (or ashA expression) in A. oryzae, as an ΔashA mutant of A. flavus was incapable of producing AFB1. Data about the production of amino acids is shown that proves fermentation with A. oryzae introduces umami taste to the product. A. oryzae is also shown to be capable of breaking down antinutritive molecules in the substrate. Research is presented that shows A. oryzae is capable of producing methionine on legume substrates, although no data was found that quantifies the methionine content of the fermented product. The review aims to combine data from different sources to give a clear overview of IAA content of (fermented) legumes in comparison to animal-based protein sources, but was unsuccessful because there is no single method for measuring and presenting protein content. In conclusion, fermentation of legumes with A. oryzae seems suitable and safe, but requires more research. Mainly, it is recommended that careful determination of IAA content of substrate and product take place and researchers obtain a better understanding of the epigenetic pathways that inhibit AFB1 production in A. oryzae.