Abstract:

Objective: To assess microbial contamination of the workshop, equipment and critical procedures during theproduction of stewed dried tofu by aerobic plate count (APC). Methods: APC levels were tested and graded according toGB4789.2-2010 and rating standard of microorganisms in the air. Results: The APC was (3.98 ± 0.14) (lg (CFU/m3))in the air of workshop, higher than 4.50 (lg (CFU/m2)) on the surface of equipment and operators’ hands, (6.21 ±0.49), (7.28 ± 1.30), (5.54 ± 0.28) and (7.32 ± 0.30) (lg (CFU/g)) in soybean, soaked beans, baked tofu and seasonedtofu, respectively, being rated as polluted to seriously polluted, and (2.48 ± 0.07), (2.47 ± 0.16), (3.01 ± 0.15) and(2.11 ± 0.30) (lg (CFU/g)) in cooked pulp, coagulated soymilk, cleaned bean curd before stewing and sterilized bean curd,respectively, all being rated as clean. Duncan’s variance analysis showed that there was a significant difference in APCbetween different production procedures. Conclusions: The poor hygiene conditions in workshop, equipment and operatorsmay lead to secondary pollution. Microbial distribution is closely related to the production process. The starting rawmaterial, soaking, baking and seasoning are the critical procedures for the safety of stewed dried tofu. Pulping, bean curding,cleaning before stewing and sterilization are critical to reduce microbial contamination.

Key words: stewed dried tofu, total colonies number, microorganism detection, safety control