Effect of fermentation time on the physicochemical and functional properties of pea protein-enriched flour fermented by Aspergillus oryzae and Aspergillus niger

Background and objectives Pea protein-enriched flour (PPEF) was inoculated with Aspergillus oryzae NRRL 5,590 or Aspergillus niger NRRL 334 to obtain limited protein hydrolysis (0%-10%). Fermented PPEF was analyzed for surface properties, water hydration capacity (WHC), oil-holding capacity (OHC), and nitrogen solubility and emulsification and foaming properties at pH values of 3.0, 5.0, and 7.0. Findings The surface charge of fermented PPEF increased over fermentation time for both fungi, whereas surface hydrophobicity decreased. In all samples, functionality (based on solubility, emulsification, and foaming) was greatest at pH 3.0 and 7.0 and lowest at pH 5.0. Fermented PPEF significantly decreased in solubility over fermentation time for both fungi, and in turn, the foaming properties were negatively impacted, whereas the emulsifying properties remained relatively unchanged. However, fermentation improved the water and oil binding properties of fermented PPEF; WHC increased from 1.46 to 2.03 g/g with A. oryzae, and OHC increased from 1.18 to 2.27 g/g with A. niger. Conclusions Fermentation of PPEF with A. oryzae or A. niger may be considered for applications requiring high WHC and OHC, respectively. Significance and novelty Fermented PPEF represents a novel protein material that should be further explored for specific food applications.