Bioactivity of probiotic whey cheese: characterization of the content of peptides and organic acids

Background: Probiotic whey cheeses have been produced for several years. It is recognized that several bacterium-mediated metabolic activities contribute differently to the final sensory and nutritional profiles of dairy products. Hence the metabolic activity of probiotic strains in a whey cheese and their contribution to the bioactivity of such matrices were investigated here, including in particular Bifidobacterium animalis, Lactobacillus acidophilus and Lactobacillus casei. Results: Both L. casei and B. animalis produce lactic and acetic acids, whereas L. acidophilus produce mainly lactic acid; these metabolites may be considered bioprotection factors. Water-soluble extracts (WSE) obtained from these cheese matrices were subjected to ultrafiltration through a 3 kDa cut-off membrane, and the eluted peptides were resolved by high-performance liquid chromatography. Different qualitative and quantitative profiles were obtained, depending on the strain. WSE were further assayed for their ability to inhibit angiotensin-converting enzyme; the <3 kDa fraction exhibited higher activities in the case of L. casei and B. animalis than the control and L. acidophilus. Conclusion: Whey cheeses with higher nutritional value were those inoculated with L. casei.