Fermentation with edible mushroom mycelia improves flavor characteristics and techno-functionalities of soybean protein

Abstract

Fermentation has been considered as an effective strategy for improving the flavor characteristics and techno-functionalities of plant proteins. However, fermentation of soybean protein with mycelia of edible mushrooms has not been reported yet. In this study, edible mushrooms of Morchella Crassipes, Hedgehog Fungus, and Shiitake mushroom were selected for mycelium fermentation of soybean protein isolate (SPI). Mycelium fermentation modified the flavor profile of SPI in strain-dependent manner as indicated by electronic nose analysis. Sourness, bitterness, and astringency of SPI were altered after fermentation with increased proportion of sweet and tasteless amino acids. While, the proportion of bitter amino acids in SPI after 6 days fermentation with Morchella Crassipes (9.88%) was significant decreased as compared with that of untreated SPI (47.95%). Besides, off flavor of SPI was improved by fermentation as indicated by HS-SPME-GC-MS analysis with the relative content of hexanal be reduced from 22.40% to 6.93% after 6 days fermentation with Morchella Crassipes. Moreover, newly formed flavor compounds of benzaldehyde and 5-hydroxymethylfurfural have been identified after fermentation of SPI with mycelia of the selected edible mushroom. Fermentation with mycelium of Morchella Crassipes for six days significantly decreased surface hydrophobicity but increased sulfhydryl content in SPI with changed structural features. Those might contribute to the increased protein solubility (81.16 ± 2.77%) and foaming capacity (221.66 ± 2.35%), while the emulsifying capacity of SPI was significantly decreased. Findings gained in this study would benefit the production of soybean protein with superior flavor and techno-functionalities for potential food applications.