Some Biochemical and Physical Changes during Manufacturing of Grey Sufu, a Traditional Chinese Fermented Soybean Curd

Abstract

Abstract In this study, grey sufu, a traditional Chinese fermented soybean curd, was prepared by ripening the salted pehtze in dressing mixture containing soy whey left over from making tofu. The biochemical and physical changes during grey sufu manufacturing were investigated. It was found that amino nitrogen, water-soluble protein, peptide and free amino acid content increased significantly during manufacturing. Meanwhile, hydrophobic amino acid proportion increased to 84.15% after ripening for 90 days. Examining the changes in short-chain fatty acids revealed that butyric acid, acetic acid and succinate increased, while lactic acid content experienced a significant decline. In addition, it was found that grey sufu was rich in butyric acid with the highest content of 25.44 mg/g dry matter, which was much higher than that of other foods known. It was suggested that high concentration of butyric acid might make grey sufu potentially helpful in controlling several diseases.