Microbiological Changes during Ripening of Chihuahua Cheese Manufactured with Raw Milk and Its Seasonal Variations.

Chihuahua cheese is a traditional cheese produced in Northwest Mexico that is consumed shortly after production. Cheeses prepared during autumn, winter and summer were collected from five dairies, and analyzed to determine seasonal influence on proximate analysis, texture profile and the microbiological dynamic during a ripening period of 270 days. Coliforms, coagulase-positive staphylococci, molds, yeast, as well as presumptive mesophilic lactobacilli, thermophilic lactobacilli, lactococci, thermophilic cocci and enterococci, were enumerated by plate count on selective agar. Manufacturing dairy had an effect on Chihuahua cheese composition and texture profile. Seasonality influence on the microbial dynamic was observed, since the highest initial counts of coliforms (5.14 log CFU/g), coagulase-positive staphylococci (4.13 log CFU/g) and mesophilic lactobacilli (7.86 log CFU/g) were detected on summer samples. Also, ripening time affected the survival of coliforms and presumptive lactococci after 270 days (1.24 and 5.89 log CFU/g respectively) while from day 90th, coagulase-positive staphylococci were absent. Microbial changes and seasonal influence provide information on the microbiota that can influence the sensorial characteristics of Chihuahua cheese.