Efficiency of Bacteriocin-like Substances Produced by Lactobacillus rhamnosus as a Biopreservative for Ras Cheese

摘要

The present work was carried out to study the efficiency of bacteriocin-like substances (BLS) produced by Lactobacillus rhamnosus as a biopreservative for Ras cheese. The in vitro mycelial inhibition percentages of Aspergillus paraceticus were 7.35, 91.14, 100 and 100% for 2, 4, 8 and 16 mg/ml~(-1), respectively whereas, they were 14.70, 94.11, 100 and 100% for Asp. flavus and 17.64, 97.05, 100 and 100% for Penicillium roqueforti, respectively. Cheese blocks were superficially treated with three concentrations of BLS (8, 16 and 32 mg/ml~(-1)) compared with control and potassium sorbate treatment. Ripening indices values decreased by increasing the amount of BLS. This agreed with the results of the cheese protein fractionation profile (SDS-PAGE). Comparing the results between fresh and ripened cheese, the degradation of protein was more evident in the control. Also, the lowest level of proteolysis was obtained in the cheese superficially treated with 32 mg/ml BLS. Finally, the use of a film containing BLS can improve the chemical, organolyptic and microbiological quality of Ras cheese.