| Congresso Brasileiro de Microbiologia 2023 | Resumo: 473-2 | ||||
Resumo:Lactic acid bacteria (LAB) are naturally present in various food matrices and are considered an interesting microbial group due to their important technological applications, especially in fermented foods. In the dairy industry, LAB play an important role either as starter, adjunct and bioprotective cultures. Oven recent years, there has been increased considerably in the market for microbial cultures for application in food, driving a continuous search for new cultures with diverse technological capabilities. Therefore, this work aimed to evaluate the technological characteristics of 40 LAB isolates obtained from different food matrices in the region of Sicily, Italy. Initially, the genetic variability among the isolates was verified through PCR amplification of repetitive extragenic palindromic sequences (rep-PCR). Then, the isolates were subjected to the spot-on-the-lawn method to identify their antimicrobial activity against following pathogens: Salmonella enterica subsp. enterica serovar Enteritidis ATCC 13076, Listeria monocytogenes ATCC 19112, Staphylococcus aureus subsp. aureus ATCC 25923, Escherichia coli ATCC 25922, Enterococcus faecalis FAIR-E77, and Shigella flexneri ATCC 12022. The technological potential was evaluated through phenotypic tests that include diacetyl production, proteolytic capacity, and acidifying activity. The rep-PCR fingerprint analysis resulted in 4 different clusters with similarity indices of at least 70% and 1 solitary fingerprints. However, there was no clustering in relation to the isolation source. Despite this, high similarity was observed regarding the identification of the isolate. None of the isolates showed antimicrobial activity against the tested pathogens. Regarding the technological potential, approximately 52.5% of isolates produced diacetyl, which is an important compound for flavor and aroma in the production of cheeses and yogurts, and other fermented foods. The presumed proteolytic activity was observed in 87.5% of the isolates. This test can presume the ability of bacteria to cause proteolysis in milk proteins, being an important parameter in cheese maturation. All isolates showed some ability to acidify milk, despite a very weak reduction of pH after 24 hours at a temperature of 25°C. In addition, the titratable acidity results, expressed as lactic acid content, confirmed the pH measurements. These results showed that the evaluated cultures may indeed have a specific potential for proteolysis and aroma production in products without causing extreme acidification. Therefore, they can add the sensorial characteristics and may also have potential for the development as adjunct cultures. Thus, further studies of quantitative technological tests regarding the production of aromatic compounds and derivatives of proteolysis are necessary, in addition to tests with the food matrix to prove the effects of technological application. Palavras-chave: biotechnology, adjunct cultures, technological properties Agência de fomento:FAPEMIG, CNPq and CAPES. | |||||