ABSTRACT
Hispanic-style fresh cheeses, such as queso fresco, have relatively low salt content, high water activity, and near neutral pH, which predisposes them to growth of Listeria monocytogenes. Biosafety constraints limit the incorporation of L. monocytogenes into cheeses manufactured via traditional methods in challenge studies, so few have focused on in situ testing of novel antimicrobials in fresh cheeses. We have developed a modular, miniaturized laboratory-scale queso fresco model for testing the incorporation of novel antilisterials. We have demonstrated the assessment of the antilisterials nisin and ferulic acid, alone and in combination, at various levels. Our results support the inhibitory effects of ferulic acid in cheese, against both L. monocytogenes and its common surrogate Listeria innocua, and we provide preliminary evaluation of its consumer acceptability.
Subject(s)
Anti-Infective Agents/pharmacology , Cheese/microbiology , Listeria monocytogenes/drug effects , Listeria monocytogenes/growth & development , Animals , Cheese/analysis , Coumaric Acids/pharmacology , Food Microbiology , Hydrogen-Ion Concentration , Microbial Sensitivity Tests , Nisin/pharmacologyABSTRACT
Of 20 Lactobacillus and 8 Bifidobacterium species examined, only Bifidobacterium breve ATCC 15700 was able to ferment starch from fava beans. Bifidobacterium breve ATCC 15700 and Lactobacillus rhamnosus GG ATCC 53103 were selected as probiotics for use in fresh-style Panela cheese. Two types of fresh cheese (with and without 3% fava bean starch) were manufactured with 3 combinations of probiotics: L. rhamnosus GG only, B. breve only, or both L. rhamnosus GG and B. breve. During 4 wk of storage at 4°C, the addition of fava bean starch to the cheese was not found to cause significant differences in the viability of either probiotic strain. However, the microstructure and texture of Panela cheese were altered, resulting in a much softer product. A sensory panel showed that the presence of added fava bean starch in Panela cheese was less desirable to consumers, whereas probiotic supplementation had no effect on perceived taste or appearance. Panela cheese could be a suitable food for inclusion of probiotic bacteria.
