Effect of refrigerated storage on microbiological, chemical and sensory characteristics of a ewes' raw milk stretched cheese

This study aimed to describe the effects of refrigerated storage up to 180 days on microbiological, chemical, physical, and sensory characteristics of a PDO ewes' raw milk stretched cheese. To this aim, a total of 224 cheeses were manufactured in four consecutive production weeks, and series of 32 of them were examined before packaging and after 15, 30, 60, 90, 120, and 180 d of storage at 4 ± 2 °C in the dark, respectively. Lactic acid bacteria cocci displayed the highest levels (7.8 Log CFU*g−1) during early storage and decreased progressively over time (7.4 Log CFU*g−1), while the opposite trend was observed for lactic acid bacteria rods (from 6.5 to 7.3 Log CFU*g−1). TMC and enterocci significantly increased during the storage. Chemical parameters showed a natural increase of proteolytic index during storage, an increase of pH (from 5.44 to 5.92), salt (from 2.08 to 2.40% of DM) and a decrease of aw (from 0.984 to 0.971). Storage modified the color of the cheeses, provoked a slight browning, while a* value (red-green) and b* value (yellow-blue) increased until 30 days and then remained unchanged. Cheese fatty acids composition didn't show particular trend during the storage, while several panel test parameters changed. Cheeses after 180 days of storage showed higher solubility, greater odor of butter and less odor of milk than fresh cheeses, that determined an high overall satisfaction of the panelists at the end of storage.