The Effect of Temperature on Physicochemical and Microbiological Aspects of Serrano Artisanal Cheese Ripening

Abstract

Abstract The serrano artisanal cheese (SAC) is a traditional raw milk dairy produced in southern Brazil. The maturation temperature plays a crucial role regarding the cheeses’ microbiological and physicochemical features and has been underexplored when it comes to unpasteurized milk dairy in Brazil. The objective of the present work is to evaluate the effect of ripening temperature on foodborne bacteria (total and thermotolerant coliforms, positive coagulase Staphylococcus and the production of its enterotoxin, Listeria monocytogenes, Escherichia coli and Salmonella spp.) and physicochemical attributes (moisture, water activity, pH, acidity and sodium chloride concentration) of SAC during maturation at 5ºC-20ºC for up to 60 days. Metagenomic analysis was also evaluated through the rDNA 16S method at ripening time of 0-60 days. The samples were safe for L.monocytogenes, E.coli, Salmonella spp. and staphylococcal toxin. The physicochemical parameters reached legal boundaries as follows: moisture, after 30 days at 5ºC; fat, after 30 days at 12.5ºC and 20ºC; fat at dry extract, after 30 days at 12.5ºC or 15 days at 5ºC. The microbiological features indicate that positive coagulase Staphylococcus reached legal conditions after 30 days when cheeses were ripped at 12.5ºC and 20ºC; thermotolerant coliforms after 30 days at 12.5ºC and 20ºC; and total coliforms after 15 days at 20ºC. Lower temperatures lead to lower inactivation rates, and Staphylococcus did not reach legal parameters at 5ºC positive coagulase regarding moisture, water activity and pH reduction. Meanwhile, sodium chloride concentration and enhanced acidity played important role regarding foodborne pathogen inactivation. The main lactic acid bacteria within the cheeses during ripening were Enterococcus sp. and Lactococcus sp.

Keywords

• raw milk cheese
• maturation
• foodborne bacteria
• acid lactic bacteria.