Effects of thermal and nonthermal processing technology on the quality of red sour soup after storage

In the present study, we investigated the effects of thermal preservation, such as pasteurization, and nonthermal preservation, including irradiation, sodium dehydroacetate (SDHA), and nisin, on the quality of red sour soup after storage. Single-factor experiments were used to optimize the parameters of different processing technologies, and the best irradiation dose and heating temperature were 4 kGy and 85℃, respectively. The optimal additive amounts of SDHA and nisin were 150 mg/500 g. During the shelf storage experiment, prepared red sour soup was stored at room temperature in the glass bottles, and further analyses were carried out up to 5 weeks of storage. The quality of red sour soup was evaluated by microflora and sensory analysis. The results showed that Lactobacillus, Streptomyces, Pediococcus, Pichia, Kazachstania, and Candida were the main microorganisms in all samples, and there were no harmful microorganisms. The sensorial attributes were observed, including different parameters, such as odor, organic acid content, color, taste, texture, apparent viscosity, and thixotropy. All of the data showed that the irradiated groups were more dramatically changed compared with the other groups, while these changes did not directly affect the sensory quality of the products. Consequently, irradiation could be used as an ideal quality preservation method for the red sour soup to reduce the impact of heat treatment and chemical additives on the quality of characteristic food.