Cheese whey fermentation with lactic acid bacteria (LAB) results in the production of lactic acid, but can also induce the proteolysis of the major whey proteins, therefore originating polypeptides with antibacterial activities. This work set out to determine if by using different types of whey (ovine, caprine and bovine), inoculated with three different LAB strains, could enhance proteolysis degradation of major whey proteins and improve antibacterial activity. Lactic acid production was monitored throughout time by using chromatographic techniques and protein variations were evaluated by electrophoretic techniques. Low Molecular Weight (LMW) polypeptides were isolated by ultra filtration and tested for their bioactivities against the model bacteria Listeria monocytogenes. Overall, results showed that consumption of whey proteins α-lactalbumin and β-lactoglobulin as well as antibacterial activities induced by fermentation were highly dependent on the bacterial strain, the type of whey used and the length of fermentation. Despite being little known by its proteolytic activity towards caseins and whey proteins, Lactobacillus casei proved to be a strain with high fermentative potential and the capacity to produce antibacterial polypeptides

Mestrado em Engenharia Alimentar - Qualidade e Segurança Alimentar - Instituto Superior de Agronomia