Nutritional evaluation of different bacterial douchi.

The aim of this study was to determine the content and/or composition of protein, peptide, amino acid, lipid and fatty acid in bacterial douchi (BD) made by different pure starter fermentation. Protein content of BD3, BD5, BD7 and BD8 was significantly higher than that of autoclaved soybean (AS). Lipid content of BD1, BD5 and BD6 was also significantly higher than that of AS. Predominant amino acids were glutamic acid (11.3-15.2%), proline (11.2-14.5%), aspartic acid (8.7-10.0%), leucine (9.2-10.0%) and alanine (7.4-8.9%). BD had EAA7 and EAA9 values of 34.4-36.4% and 40.5-41.7% respectively. Threonine with the amino acid score of 61-85 was the limiting amino acid. Triacylglycerol (82.4-88.2%) was the most abundant lipid in BD, followed by phospholipid (9.6-16.4%) and phytosterol (1.2-2.9%). Major fatty acids were palmitic (10.6-11.3%), oleic (20.5-21.9%), linoleic (54.2-55.6%) and alpha-linolenic acid (8.2-9.1%). The ratio of n-6 polyunsaturated fatty acids (PUFA) to n-3 PUFA ranged from 6.1 to 6.7. Amino acid nitrogen and trichloroacetic acid soluble protein increased from 0.2% (AS) to 1.8% (BD8) and from 1.3% (AS) to 4.0% (BD7) at the highest level respectively. Peptides with molecular weight < or = 2000Da accounted for at least 75% of total peptide. Bacterial fermentation of soybean increased amino acid nitrogen and trichloroacetic acid soluble protein except BBDC6, decreased molecular weight of 100-500 and increased 500-1000 and 2000-5000 peptides. Composition of lipids, fatty acids, and amino acids were no significant change after soybean bacterial fermentation.