Abstract:[Objective] This study aims to explore the impacts of single strain fermentation and mixed fermentation on the flavor,composition, and antioxidant activity of soybean whey.[Method] Gas chromatography-ion mobility spectrometry (GC-IMS) was coupled with E-nose and high-performance liquid chromatography (HPLC) to analyze the flavor and function of soybean whey fermented by the single and mixed strains.[Result] Compared with single-strain fermentation by Limosilactobacillus fermentum HJS-1 or Kluyveromyces marxianus HJS-2, mixed fermentation (Limosilactobacillus fermentum HJS-1 + Kluyveromyces marxianus HJS-2) effectively improved the levels of functional substances and antioxidant activity of soybean whey. Compared with non-fermented soybean whey, mixed fermentation increased the mass concentrations of soy isoflavones and organic acids in soybean whey by 65.53% and 182.39%, respectively. Moreover, mixed fermentation increased the proportions of sweet-taste amino acids and aromatic amino acids by 49% and 9%, while reducing the proportions of umami/sour-taste amino acids and bitter-taste amino acids by 16% and 42%, respectively. The ABTS+, hydroxyl, and DPPH free radical clearance rates of the soybean whey after 36 h of mixed fermentation reached (20.95±0.07)%, (9.08±0.07)%, and (37.62±0.21)%, respectively. A total of 53 volatile flavor compounds in the fermented soybean whey were identified by GC-IMS, mainly including esters, aldehydes, alcohols, and acids. Large amounts of esters such as isobutyl acetate and ethyl acetate existed in the soybean whey after mixed fermentation, which removed the beany flavor of soybean whey.[Conclusion] Mixed fermentation can effectively improve the flavor quality and antioxidant activity of soybean whey.
