Abstract: To enrich the flavor and nutritional efficacy of soymilk powder, this study investigated the effects of adding different ratios of pea peptides on the quality, nutrition and flavor of soymilk powder. The reconstitutability of soymilk powder was examined based on solubility and caking rate, and its in vitro bioactive functions were evaluated in terms of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and cholesterol scavenging capacity. The changes in the structural properties and flavor quality of soymilk powder caused by addition of pea peptides were explored by Fourier transform infrared (FTIR) spectroscopy, nanoparticle size analyzer, confocal laser scanning microscopy (CLSM), and headspace solid phase microextraction (HS-SPME)-gas chromatography-mass spectrometry (GC-MS). The results showed that the addition of 30% pea peptides to soymilk powder increased the protein content by 13.05% and solubility by 11.23%, decreased the caking rate by 4.20%, enhanced the DPPH radical and cholesterol scavenging capacity by 19.84% and 21.25%, respectively, and significantly improved the reconstitutability in hot water at 70 ℃. The structural analysis results revealed that pea peptide addition altered the secondary structure of proteins, reduced the average particle size, and resulted in more uniform particle size distribution in reconstituted soymilk, thereby improving the solubility of soymilk powder. Additionally, pea peptide addition changed the concentrations of the key flavor components geranylacetone, myristic acid, 3-methylthiopropanal, 2-methylpyrazine and 2,5-dimethylpyrazine in reconstituted soymilk, while decreasing the concentrations of off-flavor substances, such as hexanal, trans-2-nonenal, nonanal, n-hexanol, 1-octen-3-ol and naphthalene.

Key words: pea peptide-incorporated soymilk; solubility; flavor substance