Technological properties of candidate probiotic Lactobacillus plantarum strains

The study of new probiotic strains for their technological relevance and use in dairy products is important for trade and industry. Eight Lactobacillus plantarum strains isolated from Bulgarian cheeses and selected for their potential probiotic properties were characterized. In vitro tests with the API ZYM system revealed high aminopeptidase and phosphatase activity, and weak lipolytic activity. The L. plantarum strains showed also a weak proteolytic activity and were characterized as slow variants on the base of their coagulation ability. They maintained high viability in fermented milk over extended shelf-times at refrigerated temperature and demonstrated a good adaptation to 6% NaCl. Among the preservatives, only calcium propionate did not affect the growth of L. plantarum. The highest concentrations used of potassium sorbate (0.5 and 1%) and nisaplin (0.02%) decreased the bacterial growth. One L. plantarum strain was tested as an adjunct to commercially available formula for cream cheese. This candidate probiotic culture withstood the technological processing and retained high number of 107 cfu g−1 at the end of the 3 months storage period at 4 °C.