| Congresso Brasileiro de Microbiologia 2023 | Resumo: 473-1 | ||||
Resumo:Filamentous fungi can cause various issues in the dairy industry, such as visible mycelium growth on product surfaces, production of bitter flavors or gas, and the potential for mycotoxin production, which is a concern for public health. To control fungal growth, food industries typically adopt good manufacturing practices and use chemical preservatives like natamycin, potassium sorbate and sodium benzoate. However, the growing demand for "clean label" foods has led to a search for natural and healthier alternatives, including the replacement of chemical preservatives with natural compounds. This has increased scientific interest in microbial cultures with bioprotective functionality, particularly lactic acid bacteria (LAB), which are known for their ability to produce various antimicrobial compounds. Thus, this study aimed to compare the antifungal effect of 52 LAB isolates and to assess their antifungal activity with commercial bioprotective cultures. To evaluate the antifungal effects of LAB isolates, the study assessed their inhibitory effects against Aspergillus niger IOC 207 and Penicillium chrysogenum IOC 132 through in vitro tests and in simulated cheese matrices. The in vitro test was carried out in 96-well microplates, adding the spore suspension of the fungi and the cell-free supernatant (CFS) of the tested LAB; then, the microplates were incubated at 30°C for 48 hours. Absorbance values were measured (OD600) at 600 nm and antifungal activity was given in percent. The in situ test was carried out through an assay that simulates the cheese matrix in 24-well plates; these “mini-cheeses” were prepared with retentate of standardized ultrafiltered milk, and each well was inoculated with the LAB cultures and the fungi. Treatments with and without addition of starter culture were also evaluated. As a control, a commercial bioprotective culture was used. The mini cheeses were incubated for 5 days at 25°C. Initially, 52 LAB isolates were screened in the in vitro test, and from those, 5 isolates were selected for the in situ test. The selected isolates, Weissella confusa W5 and W8, Weissella paramesenteroides W9, Weissella cibaria W25, and Lactiplantibacillus plantarum Q4C3, exhibited excellent antifungal effects in the simulated cheese matrices against both fungi. However, when combined with a commercial starter culture, their antifungal activity was reduced. Despite this reduction, the study suggests that these LAB isolates have potential as bioprotective cultures in food applications. Their ability to produce antifungal compounds could be further characterized, and they could be used as adjunct cultures in future food processing. Additional research in this direction is warranted to explore their metabolic capabilities fully and pave the way for their potential use as bioprotectives in the food industry. Palavras-chave: antifungal, bioprotective culture, acid lactic bacteria Agência de fomento:FAPEMIG, CNPq and CAPES. | |||||