Changes in the Contents of Sugars and Organic Acids during the Ripening and Storage of Sufu, a Traditional Oriental Fermented Product of Soybean Cubes

Abstract

In the present study, sufu, an oriental fermented product of soybeans, was prepared by ripening the tofu cubes in Aspergillus oryzae fermented rice-soybean koji mash for 16 days at 37 °C. The sufu product was further kept at room temperature for another 30 days. Examining the changes in the sugar content revealed that stachyose, raffinose, and sucrose contents of tofu and rice-soybean koji granules decreased while levels of glucose and fructose increased during the ripening period and after storage. Glucose was the most abundant sugar detected. Four organic acids, including oxalic, lactic, acetic, and citric acid, were detected in the sufu product and koji granules after ripening. Generally, the contents of these organic acid increased as the ripening period was extended. Among them, acetic acid was the most highly detected.

High-Throughput Sequencing and Metabolomics Reveal Differences in Bacterial Diversity and Metabolites Between Red and White Sufu

“…Succinic acid and propionic acid were not detectable in all sufu samples. Lactic acid, acetic acid, and citric acid have previously been reported as the predominated organic acids in sufu (Moy and Chou, 2010). However, there were no significant differences in these high-abundance organic acids between RS and WS in our study.…”

“…Organic acids were analyzed by HPLC, as previously described (Moy and Chou, 2010), with minor modifications. Briefly, an organic acid analysis column (Atlanti T3; 10.0 × 250 mm, 5 µm; Waters Corp., Milford, MA, United States) was used.…”

“…Bacteria belonging to the genera of Lactococcus, Tetragenococcus, Streptococcus, Enterobacter, Acinetobacter, and Brevibacterium are the predominant microorganisms in sufu; however, their abundances are mostly correlated with chemical characteristics, such as salinity, ethanol content, and angkak composition (Hwan and Chou, 1999;Han et al, 2001a). Moreover, metabolomic approaches, such as gas chromatography (GC), mass spectrometry (MS), high-performance liquid chromatography (HPLC), and proton nuclear magnetic resonance have been applied to determine the metabolite profiles of sufu (Moy and Chou, 2010;Huang et al, 2018;Xie et al, 2018;Fan et al, 2019). However, few systematic studies have evaluated differences in microbial compositions and metabolites between RS and WS, which are the most commonly consumed types of sufu in China.…”

Characteristic of low‐salt solid‐state fermentation of Yunnan oil furu with Mucor racemosus: microbiological, biochemical, structural, textural and sensory properties

“…Although studies had been done to show the effects of varying salt levels of red and white furu on some physiochemical properties and textural changes (Han et al ., , ; Li et al ., ; Moy & Chou, ; Kim et al ., ; Li & Wang, ; Ma et al ., ), little work has been done on Yunnan oil furu, which is manufactured so differently that it has very distinct product characteristics. Therefore, the objectives of this work were to investigate the effect of varying salt levels on structural, textural and sensory properties of Yunnan oil furu during ripening and to provide an optimal range of salt for the manufacture of low‐salted Yunnan oil furu.…”

Development of A Lexicon for Commercial Plain Sufu (Fermented Soybean Curd)

“…Proteolysis plays a crucial role in producing acceptable sufu product during the final aging stage (Li et al 2010;Moy and Chou 2010). Glycinin (7S), one of the major storage proteins in soybeans, is partially hydrolyzed to peptides, amino acids and other small nitrogenous compounds such as amines during aging (Yasuda 2011).…”