Kinetic modeling of inactivation of foodborne bacterial pathogens in serrano artisanal cheese during ripening

Abstract

Serrano artisanal cheese is a traditional raw milk dairy product from southern Brazil. For safe consumption of raw milk products, ripening is a critical period for reducing populations of pathogenic and spoilage microorganism and, then, the knowledge on inactivation kinetics of microorganisms is necessary to guarantee food safety and quality. In the present work, inactivation kinetics of foodborne bacterial pathogens required by Brazilian regulations in serrano artisanal cheeses were statistically evaluated during ripening. The Salmonella spp., Listeria monocytogenes, coagulase-positive strain of Staphylococcus aureus and fecal coliforms were analyzed for up to 60 days. Experimental data were fitted using first-order model, Weibull and log-linear + shoulder models. Results showed no presence of Salmonella spp. and L. monogyatogenes in the cheeses through the studied period. The first-order and Weibull models presented good performance to represent coagulase-positive strain of S. aureus and fecal coliforms during ripening, although Weibull distribution showed better outcomes to experimental data. Log-linear+shoulder equation was discarded to describe the reduction of microorganism counts for physical criteria. Kinetics showed an initial resistance of fecal coliforms to be inactivated, unlike to coagulase-positive strain of S. aureus population. Modeling analysis allowed estimating serrano artisanal cheese ripening period to be longer than 33 days for achieving a safe product according to the Brazilian Regulatory Standards.

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

“…Population reduction of foodborne bacteria during ripening of serrano cheese was evaluated and results showed that dairy products are free of Salmonella spp., E. coli and L. monocytogenes through the maturation period. Pretto and coauthors [10] also observed the absence of Salmonella spp. and L. monocytogenes on SAC, although is not rare to find these bacteria on artisanal dairy products [19][20].…”

“…Souza and coauthors [9] observed that serrano artisanal cheeses' ripening process should be longer than 30 days, but not necessarily 60 days, in order to allow microbiological stabilization. Pretto and coauthors [10] observed that ripening SAC for 33 days is enough to reach a safe foodborne microbial pattern. But there is still the need for food science and technology efforts to properly produce SAC products safely with a low ripening time.…”

“…Since SAC products are typically produced by small cheese makers characterized by small scale production, they present low parameters of production control [8][9][10][11], including ripening rooms' temperature. In the study of Souza and coauthors [9], experimental procedures were evaluated during the winter and summer periods, whereas Pretto and coauthors [10] did not control the maturation temperature and estimated to be approximately 10ºC. According to the current legislation, ripening must happen at a temperature above 5ºC [43], but in Rio Grande do Sul, the maturation is allowed to happen at room temperature [12].…”

Unveiling Safety Concerns in Brazilian Artisanal Cheeses: A Call for Enhanced Ripening Protocols and Microbiological Assessments

“…However, in most studies, Salmonella sp. [ 12 , 15 , 18 , 28 , 33 , 35 , 36 , 48 , 49 ] and L. monocytogenes [ 10 , 13 , 18 , 33 , 36 , 40 , 48 , 49 ] were absent in the various kinds of artisanal cheese surveyed. It is worth noting, though, that Allaion et al [ 34 ] detected 8 positive samples (out of 100) for Salmonella by PCR, but only one was confirmed by the culture-dependent method.…”

“…Concerning the Serrano cheese produced in Santa Catarina state, two of the studies in the reviewed literature [ 15 , 41 ] demonstrated that 60 days of ripening may not be enough to meet the legal parameters since L. monocytogenes was present at 35 [ 41 ] and 60 days [ 15 ] of ripening. However, for Serrano cheese produced in Rio Grande do Sul state, Souza et al [ 68 ], Pretto et al [ 48 ], and Ströher et al [ 49 ] indicated a minimum ripening time ranging from 30 to 33 days, which is a much shorter ripening period that can still reach acceptable microbiological levels than those required by Normative Instruction SEAGRI N° 7 [ 63 ]. It is important to highlight that Ströher et al [ 49 ] demonstrated that the refrigerated temperature (5 °C) determined by IN 7/2014 is not adequate for ripening this type of cheese.…”