The methods described in GB/T were used to measure the moisture, crude fat, total nitrogen, and crude protein contents in seven commercially available samples of sweet bean sauce. An automatic amino acid analyzer and high performance liquid chromatography were employed to analyze the free amino acids and nucleotides in the sweet bean sauces, respectively. The molecular weight distribution of small peptides in the sweet bean sauces was determined by size exclusion chromatography (SEC), and the degree of hydrolysis, average peptide chain length, and taste activity value (TAV) of amino acids in sweet bean sauce, as well as their contributions to the taste were calculated and analyzed. The experimental results showed that the moisture, crude fat, total nitrogen, and crude protein contents in seven commercially available samples of sweet bean sauce were 51.42%, 1.84%, 1.284%, and 7.32%, respectively. The total free amino acid contents in the seven pastes ranged from 1.55~2.78 g/100 g, and the most abundant amino acids were proline, glutamic acid, leucine, and aspartic acid. Among them, glutamic acid had the highest TAV (7.00-25.67) and had an important contribution to the taste of umami. Hypoxanthine (Hx) was the dominant nucleotide in sweet bean sauce (3.19~4.87 mg/100 g), but did not have a direct impact on the taste (TAV < 0.5). The small peptide content in sweet bean sauce was in the range of 0.55~3.31 g/100 g; the average peptide chain length (PCL) was between 2 and 4, and the molecular weight distribution was in the range of 221~445 u. Additionally, these small peptides contributed to the taste of umami to some extent.
