Changes in quality components and antioxidant activity of peony seed soy sauce during low‐salt solid‐state fermentation

Abstract

BACKGROUND In this study, the fermentation conditions of peony seed soy sauce (PSSS) koji were optimized by response surface method, and the quality components and antioxidant activity of PSSS were investigated at different low‐salt solid‐state fermentation stages. RESULTS Results of response surface method showed that the optimal fermentation conditions were 460.6 g kg−1 water content, 48.6 h culture time, 31.5 °C culture temperature and ratio 2.1:1 (w/w) of peony seed meal:wheat bran, with the highest neutral protease activity (2193.78 U g−1) of PSSS koji. PSSS had the highest amino acid nitrogen (7.69 g L−1), salt‐free soluble solids (185.26 g L−1), total free amino acids (49.03 g L−1), essential free amino acids (19.58 g L−1) and umami free amino acids (16.64 g L−1) at 20 days of fermentation. The highest total phenolics were 5.414 g gallic acid equivalent L−1 and total flavonoids 0.617 g rutin equivalent L−1, as well as the highest DPPH radical scavenging activity (86.19%) and reducing power (0.8802, A700) of PSSS fermented at 30 days. Sensory evaluation showed that fermentation of 20 days and 25 days could produce a better taste and aroma of PSSS than 15 days and 30 days. CONCLUSION PSSS had the highest quality components in the middle of fermentation (20 days) and the highest antioxidant activity in the late fermentation period (30 days). These results demonstrated that peony seed meal could be used to produce high‐quality soy sauce with high antioxidant activity. © 2023 Society of Chemical Industry.

A Method of Reducing Salt Content in Fermented Soy Sauce Improves Its Flavor and Quality

“…The alkaline and neutral proteases were the most active in the initial system due to the generally high pH at the beginning of the fermentation. As the fermentation progressed, the pH of the system gradually decreased, leading to an increase in acid protease activity [ 21 ]. The raw soybean meal material was defatted of extruded soybeans, because after extrusion treatment, it is distributed in flakes, without the three-dimensional particles of soybeans [ 28 ].…”

“…The content of amino acid nitrogen was calculated according to the volume of NaOH used. Total nitrogen (TN) was measured according to Zhang et al [ 21 ]. Approximately, 2 mL soy sauce was added to the digestion tube and mixed with 0.2 g CuSO 4 , 3 g K 2 SO 4 , and 10 mL H 2 SO 4 and heated to 450 °C for 4 h. The total nitrogen content was measured by an automatic Kjelter nitrogen detector (RK-9870, RayKol Co., Ltd., Xiamen, Fujian, China).…”

Developing a High-Umami, Low-Salt Soy Sauce through Accelerated Moromi Fermentation with Corynebacterium and Lactiplantibacillus Strains

“…As for G4, the amino acid nitrogen finally reached 0.92 g/100 mL, reaching the first level of China's national soy sauce standard. In the low-salt solid-state fermentation process of soy sauce by Zhang et al [37], the amino acid nitrogen reached 0.7 g/100 mL. Additionally, during the low-salt fermentation of doubanjiang (broad bean paste) with the salt concentration of 11%, the amino acid nitrogen reached 1.0 g/100 mL after 50 days [31].…”