Evaluation of the Impact of Whey Edible Coatings with Bioprotective Cultures and Thyme Essential Oil Applied to Cheese

This research work evaluated the application of whey-based edible coatings to cheeses. Coatings were prepared with a bioprotective culture (BC) containing Lacticaseibacillus paracasei and Lacticaseibacillus rhamnosus alone, or in conjunction with thyme essential oil (TEO). The samples containing the BC or the BC plus TEO were compared with cheeses without coating, with cheeses with whey-based coatings without BC or TEO, and with cheeses treated with natamycin. The cheeses were evaluated regarding their physicochemical, microbiological, and sensory properties. All cheeses produced were classified as full-fat (≥45–60% fat in dry matter—FDM) and semihard (>54–<63% moisture in the defatted cheese—MDC), with an exception made for the control cheese, which presented lower levels of MDC, graded as hard (>49–<56% MDC). Most of the parameters evaluated presented significant differences between samples and as a result of ripening time. Regarding color parameters, it was observed that, after ripening, the external color of the samples with the whey coating presented higher lightness values (L*), higher a* values, and lower b* values. These differences clearly resulted from the white color imparted by the coating. Significant differences were also observed with respect to the texture parameters of the cheeses. The samples containing the BC or the BC plus TEO presented higher values for hardness and chewiness. In what concerns the microbiological evaluation, in all cases, lactic acid bacteria counts increased from log 7.5–8 CFU/g on the first day to ca. log 10 CFU/g at the end of the ripening period. Yeast and mold counts were significantly lower in samples containing the BC or the BC plus TEO, with values of ca. log 3 CFU/g and log 2.5 CFU/g, respectively. These values are like those obtained in samples with natamycin, with 1–2 log cycles below those of cheeses without treatment. However, the use of BC and BC plus TEO had a negative impact on the sensory properties of cheeses. Future work should evaluate the synergistic effect of different BCs and EOs.