| Congresso Brasileiro de Microbiologia 2023 | Resumo: 306-1 | ||||
Resumo:The dairy industry faces a significant challenge in preventing the growth of spore-forming bacteria, particularly Bacillus cereus, which has raised concerns about the safety of processed cheeses (PC). To address this issue and extend the shelf life of PC, melting salts containing phosphorus pentoxide (P2O5) have been considered as a potential strategy. In this study, we investigated the bacteriostatic effect of six melting salts, with varying levels of P2O5, in PC samples deliberately contaminated with B. cereus spores. Six treatments were performed according to the final P2O5 content of the melting salts combinations (F1 = 17.25%; F2 = 59.7%; F3 = 62.03%; F4 = 63.0%; F5 = 65.7%; F6 = 66.0%). PC samples were produced by pasteurization (PST) and creaming (CRE) methods, and inoculated with a mix of spores of B. cereus INV 10(3) and B. cereus DSM 626 at 1 × 106 spore/g. The samples were subjected to B. cereus enumeration and spores enumeration throughout 120-days of storage (days 0, 15, 30, 45, 60, 90 and 120) at 6 and 30 ºC. In total, 672 samples were produced. The results indicated that storage temperature, choice of melting salts, and its dosage significantly influenced bacterial growth in PC. The CRE method and higher P2O5 content demonstrated an enhanced inhibitory effect. In details, the results indicated that most samples stored at 6 ºC did not show bacterial growth, exhibiting a bacteriostatic effect against vegetative cells and a reduction in spores count during 120 days of storage. Conversely, samples stored at 30 ºC exhibited different behavior, where F6 was the only treatment able to inhibit B. cereus growth. The absence of spore growth at 30 ºC suggested that spores could germinate from their resting state, resume multiplication, and normal metabolic activity. Regarding the processing method, our results show that the growth of B. cereus vegetative cells occurred faster in PC-PST samples. There are no articles available in the literature that compare processing methods with the inhibitory effect of melting salts in PC. However, as the CRE process is more extensive, it may increase the Ca2+ exchange of para-casein micelles for Na+ ions (introduced by sodium phosphates), consequently, available Ca2+ will be less to maintain bacterial metabolism. The specific formulation of the melting salts also influenced the inhibitory effect. Although F6 with the highest P2O5 content showed the best inhibitory effect and maintained the PC color up to 120 days of storage, F5 has practically the same P2O5 content and did not show the same behavior. Based on the results here described, the appropriate melting salts represent a promising approach to control B. cereus in PC. The present study, for the first time, showed that the CRE process and the P2O5 content can improve the inhibitory effect of melting salts. Further studies are needed to identify the specific melting salt composition responsible for bacterial inhibition. Palavras-chave: dairy, emulsifiers, microbiological stability, spore-forming bacteria Agência de fomento:CAPES (Financial code 001), CNPq and FAPEMIG. | |||||