Testing commercial biopreservative and bioprotective cultures to enhance MAP packed fresh sheep ricotta cheese shelf-life”.

Industrial production of fresh ricotta cheese from sheep’s milk provides the combined use of modified atmosphere packaging (MAP) and refrigerated storage intended to extend the shelf-life. Due to its composition, and inherent physical, chemical properties, fresh ricotta cheese support the growth of pathogens or spoilage psychotrophic bacteria during storage. The aim of the present study was to evaluate commercial biopreservative and bioprotective cultures towards growth of spoilage microrganisms during refrigerated storage of MAP fresh ricotta cheese made from sheep’s milk. Storage tests at 4°C were carried out on MAP ricotta cheese blank and experimental units, inoculated either by spraying on the surface: culture A including Enterococcus faecium, Lactobacillus plantarum e Lactobacillus rhamnosus; culture B including Carnobacterium spp; a microbial fermentation complex. Blank and experimental units were stored at 4°C and triplicate samples were analyzed at 7, 14 and 21 days after inoculation for Total Bacterial Count, LABs, Enterobacteriaceae, Pseudomonas spp, moulds and yeasts. Culture A and the fermented complex showed no significant differences in Pseudomonas fluorescens counts as compared to uninoculated blank samples. Promising results were obtained with culture B, which showed Pseudomonas fluorescens concentration of 1 log lower as compared with fermented complex and blank samples at all sampling times. This suggests a good adaptation of Carnobacterium which during refrigerated storage increases in number. Further investigation is currently being conducted to assess the efficacy of Carnobacterium and the possible changes in sensory properties