Broad bean fermentation is of vital importance in PixianDouban (PXDB) production, as well as a key process for microorganisms to degrade protein, which lays the foundation for the formation of PXDB flavor. In this study, two fungi and bacteria were screened, and their morphology, molecular biology, growth, and enzyme production characteristics were analyzed, and then they were applied to the broad bean fermentation simulation system. The protein, peptide, amino acid, amino nitrogen, and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) in the system were evaluated. The results showed that the four microorganisms were Aspergillus oryzae, Aspergillus jensenii, Staphylococcus gallinarum, and Enterobacter hormaeche. Aspergillus oryzae had the highest protease activity at pH 7.0, while the other three strains had better enzyme activity stability under neutral acidic conditions. And the total protein (F1 and F2 were 18.32 g/100 g, 19.15 g/100 g, respectively), peptides (11.79 ± 0.04 mg/g and 12.06 ± 0.04 mg/g), and amino acids (55.12 ± 2.78 mg/g and 54.11 ± 1.97 mg/g) of the fungus experimental groups (F) were higher than the bacterial experimental groups (B). In addition, the enzyme system produced by fungi exhibited a stronger ability for albumin (20 kDa) and glutenin (<30 kDa) deterioration in neutral conditions, while the bacterial enzyme system was more efficient in degrading albumin (<30 kDa) and glutenin (20–30 kDa) in acidic conditions, as indicated by SDS‐PAGE. These findings showed that both bacteria and fungi played an important role in the degradation of protein in different fermentation stages of broad bean fermentation.Practical applications: There is a lack of comprehensive understanding of the protein composition and protein degradation mechanism of broad beans in the fermentation stage of PXDB. This research work explored the differences in the degradation of PXDB fermented protein by different microorganisms, and provided a theoretical basis for optimizing the production of PXDB and improving the quality of PXDB.

The objective of this study was to identify the key aroma compounds of Dongpo pork dish (DPD) and to explore the changes in key aroma compounds of DPD during the storage period. Quantitative descriptive analysis (QDA) combined with two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) was employed to investigate the aroma characteristics and the volatile profiles of DPD. Further, a sensomic approach was used to decipher its key aroma compounds. The typical flavors identified in DPD were described as meat, grease, garlic, wine, soy sauce, and spice flavors by the QDA. The key aroma compounds contributing to the flavor of DPD include 2-heptanol, 1-octen-3-ol, hexanal, (E)-2-octenal, 3-methylthiopropanal, decanal, ethyl caproate, 2,5-dimethylpyrazine, and dimethyl trisulfide. In addition, the changes of key aroma compounds of DPD at different storage temperatures (25 °C, 4 °C) were explored, and the results demonstrated that the key aroma compounds showed an overall trend of attenuation with the increase in time. The content of ethyl caproate decayed by more than 60%. Compared with the storage temperature of 25 °C, DPD storage at 4 °C was more effective in slowing down the change of key aroma compounds. These results can provide theoretical evidence for the flavor modulation and the industrial production of DPD.

The complex coacervation of soybean protein isolate and polysaccharide has been widely applied for preparing biopolymer materials like microcapsule. In this study, hydrolytic soy protein isolate (HSPI) was prepared by mild hydrolysis of soy protein isolate (SPI) with fungal protease 400 (F400). The degree of hydrolysis (DH) for the enzymatic products was controlled at 1%–5%. Emulsification, oxidation resistance, and thermal stability were used to evaluate the performances of HSPI with different DH. The results showed that the HSPI with the hydrolysis degree of 2% had the optimal property. Subsequently, the complex polymer of HSPI/SA was prepared by the coalescence reaction of HSPI and sodium alginate (SA). The turbidity curves manifested the optimal complex coacervation occurred at the ratio of 7:1 (HSPI:SA). Fourier transform infrared spectroscopy (FTIR) presented that the reaction involved electrostatic interactions between ‐NH₃⁺ in HSPI and ‐COO⁻ in SA. Isothermal titration calorimetry experiments indicated that the complex coacervation reactions of HSPI and SA arose spontaneously. The microencapsulation by complex coacervation of HSPI and SA was further produced for embedding sweet orange oil. The thermogravimetric analysis (TGA) result revealed that the microencapsulation system of HSPI/SA had a better heat resistance than that using the SPI/SA complex polymer.