Dados do Trabalho

Título

INACTIVATION KINETICS OF SPORES OF Bacillus cereus IN WHOLE MILK YIELDED BY HIGH-INTENSITY ULTRASONIC

Introdução

The use of emerging technologies to reduce microbial population microorganisms in food has become relevant in recent years. Non-thermal treatments, such as ultrasound, have emerged as promising methods for bacterial inactivation. Regarding dairy product contamination, Bacillus cereus poses a concern due to its ability to resist chemical and physical agents, its resistance structure called spores, and its toxigenic and spoilage characteristics. In this sense, this study aimed to assess the inactivation parameters of B. cereus (ATCC 14579) under different High-Intensity Ultrasound (HIUS) conditions.

Material e Métodos

The experiments were performed for spores at 20 kHz and a maximum power of 500 watts and 90% amplitude. Spores were inoculated separately in whole pasteurized milk with an initial concentration of 8,03 Log Spore/mL. The inoculated samples were treated by HIUS for 10 and 15 minutes. The samples were collected every 1 minute to assemble the survival curves. The survival spore fraction was enumerated using heat shock (70°C for 15 minutes) and plated in Agar Nutrient. The plates were incubated at 30°C for 24 hours. The survival curves were fitted in Ginafit using the Weibull Model.

Resultados e Discussão

The results revealed that the first decimal reduction (δ) for 10 minutes was 67.74 minutes, and the curvature parameter (p) was 0.74. Meanwhile, for 15 minutes, the δ value was 10.76 minutes, and the p value was 0.38. Concerning the reduction in the spore population, 0.22 and 1.11 log reductions in spores/mL were observed for 10 and 15 minutes.

Conclusão

Increasing the time resulted in a decrease in spore resistance during treatment, which is related to the loss, mainly of the exosporium, the outermost layer of the spore structure. Overall, ultrasound treatment has demonstrated promising results in the inactivation of B. cereus. These results provide new frontiers for food safety management in the dairy industry.