Effect of Soybean Varieties on the Fibrinolytic Activity and Sensory Characteristics of Douchi

Abstract

Douchi is a traditional Chinese soybean‐fermented food. For preparation of a functional douchi with high fibrinolytic activity, the effect of soybean variety on the fibrinolytic activity and sensory characteristics of douchi was investigated. Douchi was prepared by inoculating the cooked soybean made from 15 soybean varieties [Glycine max (L.) Merr.] with Bacillus subtilis DC33 and fermented at 30C for 30 h. The soybean variety affected the fibrinolytic activity, amino nitrogen and sensory characteristics of douchi significantly. The soybeans that had higher soluble sugar and smaller 100‐grain weight produced the better douchi with higher fibrinolytic activity. Yellow soybeans with round seeds were more appropriate to process douchi than black ones. Longxiaolidou 1 was screened out as the optimal variety for processing fibrinolytic douchi with regard to sensory properties. It is suggested that varietal differences should be considered when selecting soybeans for douchi production. PRACTICAL APPLICATIONS Douchi is a traditional soybean‐fermented food with a long history; however, there is very little research about douchi. Recently, douchi are still mostly processed by the traditional natural fermentation with a small scale of production. Therefore, the processing of douchi is not yet industrialized. Comparing douchi to material soybean, the physiological activities in douchi has a great improvement. In order to improve the thrombolytic activity in douchi, the douchi in this study is prepared by inoculating Bacillus subtilis DC33 with a high fibrinolytic enzyme yield to produce functional douchi. The effects of soybean varieties on the traits and sensory characteristics were studied. The optimal soybean variety for processing fibrinolytic douchi was screened out. The result has the guiding significance to process fibrinolytic douchi.

Isolation and identification of an effective fibrinolytic strain Bacillus subtilis FR-33 from the Chinese doufuru and primary analysis of its fibrinolytic enzyme

“…A number of investigations have been done for this purpose, and indeed some new fibrinolytic strains and their enzymes have been identified (Wang et al, 2008;Yoon et al, 2002). Different kinds of fermented foods and even different varieties of raw materials for fermented foods produce different activity from fibrinolytic enzymes (Luo et al, 2010). The Chinese soy cheese doufuru is a traditional soybean-fermented food with a long history; however, there is little research on its fibrinolytic strains.…”

“…Earlier, Bao et al (2002), Yang and Zhang (2007) and Ma et al (2007) each reported a strain from natto with a fibrinolytic activity of 786, 1033 and 1722.4 IU/mL, respectively (Wang et al, 2008;Yoon et al, 2002). Different kinds of fermented foods and even different varieties of raw materials for fermented foods produce different activity from fibrinolytic enzymes (Luo et al, 2010). Tan et al (2009) isolated a strain from douchi with a fibrinolytic activity of 1225.5 IU/mL.…”

Changes in enzymatic activities during “koji” incubation and natural fermentation of soybean paste

“…Oil and protein, together, represents 60% of dry soybeans by weight, protein at 40%, and oil at 20%. The carbohydrate and the ash represent 35% and 5%, respectively (Luo et al, ; Yu et al, ). Soybean paste was produced by two steps of fermentation processes, namely, koji and moromi fermentation.…”

Correlation Between Protein Hydrolysates and Color During Fermentation ofMucor-TypeDouchi

“…There are three types of douchi based on the microorganisms used for fermentation, which include the Mucor-type, Bacteria-type, and Aspergillus-type douchi. The Aspergillus-type douchi, [1][2][3][4] and Bacteria-type douchi [5][6][7] have been widely researched on their physical, chemical, and functional properties; however, few reports on the Mucor-type douchi are available, and most of these have focused on the comparisons of various activities among the different types of douchi. Li et al [8] found that douchiqu fermented with Aspergillus oryzae, Mucor-wutungkiao, Bacillus subtilis natto, and Bacillus subtilis B1 had significantly different (p < 0.05) angiotensin-converting enzyme (ACE) inhibitor activities, with decreasing IC 50 values of 0.4991, 0.3535, 0.2294, and 0.0901 mg/mL, respectively.…”