Search

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. [ABSTRACT FROM AUTHOR]

As potential biomass resources, biomass waste products have been considered worldwide in recent decades. Peony seed meal (PSM) is a kind of agricultural resource waste containing polyphenols, in particular flavonoids. In this study, the total flavonoids of PSM were extracted and purified by AB‐8 macroporous resin (MR), the antioxidant activities of three extract fractions were evaluated, and the total flavonoids were encapsulated with alginate and chitosan by the complex coacervation method. After purification, the yield of total flavonoids was 11.32% and the content in the product increased to 42.89% ± 2.66. The antioxidant activities of three fractions on ·OH, DPPH, and ABTS assays exhibited the following descending order: ethanol elution fraction (ELF) > ethyl acetate extract fraction (EAF) > ethanol extract fraction (EEF). The single‐factor assay showed that the encapsulated total flavonoid microcapsules (EFMs) were prepared with a chitosan concentration of 10 mg/ml, a sodium alginate concentration of 30 mg/ml, a calcium chloride concentration of 50 mg/ml, a ratio of sodium alginate to total flavonoids of 1:3, a flavonoid concentration of 40 mg/ml, and an encapsulation yield of 80.7%. Most microcapsules are smooth‐faced, spherical and uniform in size ranging from 2 to 3 mm in diameter. In vitro release studies suggested that the EFM was stable at pH 1.2 and dissolved at pH 7.5. The result indicated that the EFM is worthy for the development of functional foods and supplements, and PSM could be a potential resource in the food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]