Effects of γ-ray irradiation on insect pests, physicochemical properties, and microbial community of strong-flavor Daqu during maturation

Abstract

Daqu is the fermentation starter of Chinese Baijiu, which is one of the six major types of liquor in the world. However, the incubation and maturation processes of Daqu are prone to infestation by pests, resulting in compromised quality and decreased grade. Irradiation technology, as an effective insecticide, has been applied to the insecticide treatment of grain. In this study, γ-ray irradiation was used to control pests during the maturation of Daqu. By analyzing the changes in the microbial communities and physicochemical properties of Baijiu Daqu bricks during maturation with time and irradiation dose, an optimal irradiation dose was obtained. The results showed that after γ-ray irradiation treatment at 0.27–0.36 kGy, all stages of insect pests in Daqu died within one month. Irradiation at a dose of 0.27 kGy could improve saccharifying power and liquefying power, and reduce acidity. Furthermore, a positive correlation was found between saccharifying power and Lactobacillaceae, Marinilabiliaceae, and Saccharomycopsidaceae, as well as between liquefying power and Lactobacillaceae, Aspergillaceae, and Phaffomycetaceae. Additionally, the number of pests positively correlated with Bacillaceae, Thermoactinomycetaceae, Thermoascaceae, and Trichocomaceae, suggesting that the activity of pests in Daqu might lead to an increase in the proportion of these microorganisms. This work provides a reference for the control of insect pests and microorganisms in Daqu and offers new insights for the application of irradiation technology in the Baijiu Daqu industry.