An assessment of the occupational environment contributing to the microbial contamination and diversity of leisure dried tofu

This study examines the total viable counts (TVC) of air, contact surfaces, raw materials, and semi-finished products throughout the production leisure dried tofu (LD-tofu) at three different companies. High-throughput sequencing was used to analyse the microbial diversity of fermented soybean whey (FSW), marinade, and LD-tofu to evaluate the effect of occupational environment on the microbial diversity of LD-tofu. Results indicated that the average TVC of marinade and LD-tofu was 3.79 and 1.83 lg CFU/g, respectively, which were within clean levels. The workshop air (4.14–5.27 lg CFU/m 3 ), contact surfaces (4.61–7.01 lg CFU/m 2 ), FSW (5.88 lg CFU/g), and tofu (4.89 lg CFU/g) were within mild to severe contamination levels. The pressing wooden frames were within severe contamination levels, as they are difficult to clean and may have residual soybean residue. Pearson correlation analysis showed that Lachnospiraceae, Moraxellaceae, and Bacillaceae were closely related to the TVC of FSW, while Vibrionaceae, Pseudomonadaceae, and Burkholderiaceae were closely related to the TVC of LD-tofu and marinade. This study provides scientific basis for improving the microbial control of the production environment, equipment, and raw materials for LD-tofu production, as well as the theoretical basis for the storage and safety control of soybean products. • Microbial safety during the production process of LD-tofu is of utmost importance. • Microbial contamination occurs in the workshop air and on contact surfaces. • The pressing wooden frame is considered a serious contamination level. • FSW, marinade, and products are key processes in the production of LD-tofu. • The marinating processes can affect the TVC and the bacterial community of LD-tofu.