| Congresso Brasileiro de Microbiologia 2023 | Resumo: 335-1 | ||||
Resumo:Chocolate is a globally beloved food known for its sensory appeal. It is characterized by a minimum cocoa solids content, high fat, and low water activity. The presence of Salmonella in chocolate raises food safety concerns, with outbreaks reported since the 1960s. The most recent case occurred in Belgium in 2022, resulting in at least 450 cases. Despite chocolate not being a favorable environment for microbial growth, Salmonella cells that accidentally contaminate the product can persist through various processing stages. This is due to their resilience to osmotic stress, which also enhances their thermal resistance. Understanding the impact of processing stages, like roasting, conching, and storage, is vital to accurately assessing associated risks. Tests conducted by our research group indicate that commonly used methods to quantify Salmonella in chocolate may underestimate the pathogen's population, impacting the accuracy of predictive microbiology studies. Our aim is to compare the efficacy of different culture-dependent quantification methods for recovering inoculated Salmonella in milk chocolate. To conduct the experiment, standard milk chocolate with butter, cocoa liquor, sucrose, whole and skim milk powder, and emulsifiers were prepared. After homogenization and refining, the mixture was conched at 60 °C/2 h in a stainless-steel reactor with 200 rpm agitation. After cooling to 45 °C, the chocolate was inoculated with Salmonella Typhimurium 87.09 at two concentrations (106 or 103 CFU/g). Salmonella population on the suspension was confirmed using a spread plate technique on XLD agar, and this data was used to calculate the estimated Salmonella population in the chocolate. Subsequently, samples of contaminated chocolate were collected for quantification of the Salmonella population using different methods, including 5 diluents, 6 plaque enumeration methods, and the most probable number test, resulting in 31 distinct assays, replicated twice, for each inoculum level. The quantified population was compared with estimated population in log (CFU/g). The data were subjected to ANOVA and Tukey test (p≤0.05) to compare the recovery efficiency. For lower inoculum levels, the recovered Salmonella population diverged by 0.60 to 1.78 log from the estimated population, and at higher levels, this discrepancy ranged from 0.89 to 2.49 log. Reconstituted skim milk with 1% brilliant green favored better recovery, while Lactose Broth with Triton-100 resulted in poorer recovery, on average. Regarding plating techniques, Pour Plate on TSA and Spread Plate on TSA with XLD overlay demonstrated greater cell recovery, while Spread Plate on XLD exhibited less satisfactory outcomes. These data indicate that commonly used methods may not provide efficient Salmonella recovery in chocolate, potentially underestimating its true population. This might be due to bacterial cells trapped within fat globules or a viable but non-culturable state induced by chocolate's composition and low water activity. Studies using electron microscopy and flow cytometry could shed light on these hypotheses. Additionally, we should investigate the impact of different chocolate formulations, such as dark and white chocolate, on recovery performance, as well as the behavior of other Salmonella serotypes. Standardizing an efficient quantification method is essential for generating robust data on Salmonella behavior in chocolate, crucial for process design and risk assessment studies. Palavras-chave: Chocolate processing, Food Safety, Low-moisture foods, Quantification Methods Agência de fomento:Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) | |||||