Application of antimicrobial coating based on carboxymethyl cellulose and natamycin in active packaging of cheese

The effects of carboxymethyl cellulose (CMC)-natamycin (N; 0.05 and 0.5%) coating on the quality of high-moisture mozzarella cheese (HMMC) were examined. The cheeses were immersed in the coating solutions and then kept at 7 °C for 8 days and microbial specifications (i.e., total mesophilic count, total psychrophilic count, lactic acid bacteria, and yeast-mold), pH, weight loss, and sensory properties were examined. The results of the agar spot diffusion assay represented inhibitory effects of CMC-N coating solution on Aspergillus flavus, A. fumigatus, A. niger, Penicillium citrinum, and Candida albicans. In HMMC, the natamycin-free CMC coating caused a significant decrease (p < 0.05) in all microbial groups, while the addition of natamycin to the coating only reduced the count of mold and yeast. As a result, the coating with natamycin at 0.05 and 0.5% represented a 0.6 and 0.9 log cycle reduction in yeast-mold populations, respectively. Based on the total mesophilic count, the control samples reached the 7 log CFU/g on day 4, indicating a 4-day shelf life of HMMC, while in HMMC coated with and without natamycin this limit was achieved on the 8th day of storage, which indicates that the coatings have doubled the HMMC shelf life.