Study of Enterobacteriaceae during the manufacture and ripening of San Simón cheese (original) (raw)
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Microbiological Study of Arzúa Cheese (NW Spain) Throughout Cheesemaking and Ripening
Journal of Food Safety, 1994
Changes duringproduction and ripening in the microbialflora of 1 I batches of Anua, a soft cheese made from raw cow's milk, were investigated. me following microbial groups were counted on the surface and interior of the cheese: total viable count (TVC), lactic acid bacteria (LAB), halotolerant flora, enterococci, proteolytic enterococci, staphylococci, Staphylococcus aureus, Enterobacteriaceae, faecal coliforms, molds, yeasts, Listeria spp. and (in milk) Brucella spp. pH and water activiry were also determined. TVC and LAB were, generally, more than 9 log (cfulg). Enterococci counts increased gradually, reaching values in excess of 6 log units. Halotolerant jlora and staphylococci remained practically constant throughout ripening, at 6-8 and 5-7 log units, respectively. Maximum Enterobacteriaceae and faecal coliform counts exceeded 7 and 6 log units, respectively. Brucella spp. were not detected in any of the milk samples. Listeria spp. were detected in four batches, and Listeria monocytogenes in two.
Brazilian Journal of Microbiology, 2013
The ripening process of Serro Minas cheese, one of the most popular cheeses produced with raw milk in Brazil, was studied over the course of 60 days of ripening during dry and rainy seasons. Brazilian legislation prohibits the production of cheese from raw milk unless it was submitted to a maturation period greater than 60 days. However Minas Serro cheese is sold within a few days of ripening. A total of 100 samples of Serro cheese were obtained from five farms; 50 samples were collected during the dry season (winter in Brazil) and 50 samples were collected during the rainy season (summer in Brazil). From each farm, ten cheeses were collected during each season after two days of ripening. Our results showed high levels of total and fecal coliforms at the beginning of the ripening period (approximately 4 Log MPN/g with 3 days of ripening) that decreased with 60 days of ripening reaching almost 1.5 Log MPN/g. Contamination by coagulase-positive staphylococci was reduced by the end of the ripening period. Salmonella spp. was not detected. The staphylococcal enterotoxins B and C were detected in 1% and 4% of the cheeses, respectively, after 30 days of ripening. These results suggest that the ripening process was not effective in eliminating staphylococcal enterotoxins from the cheese. However, none of the investigated strains of Staphylococcus spp. isolated from Serro cheese produced enterotoxins A, B, C or D. The high pathogen and coliform levels at the beginning of the ripening process for the cheese produced during both seasons indicate the need for improvement of the sanitation of the manufacturing conditions.
On the microbiology of Serra da Estrela cheese: geographical and chronological considerations
Food Microbiology, 2000
Serra da Estrela cheeses, produced following artisanal practices from raw ewe's milk in two consecutive years in ¢ve selected dairies, were sampled throughout a 60-day ripening period. The viable numbers of the major microbial groups (Enterobacteriaceae, staphylococci and yeasts, as well as such lactic acid bacteria as lactobacilli, lactococci and enterococci) were determined and statistical signi¢cance of the results was assessed. Signi¢cant di¡erences in the viable counts of lactococci, lactobacilli, enterococci, Enterobacteriaceae and staphylococci were found for the various geographical locations, whereas the year of manufacture played a signi¢cant role only upon the viable numbers of yeasts and staphylococci.These data back up the claim that those microbial families usually implicated with health hazards are prone to a wide variability, which re£ects the intrinsic heterogeneity associated with production and handling of raw milk in traditional cheesemaking.
The spatial distribution of bacteria in Grana-cheese during ripening
Systematic and Applied Microbiology, 2012
The microbial composition and its spatial distribution of Grana Trentino, a hard Parmesan-like cheese, was determined, from vat milk to cheese. After cutting along the vertical axis of the cheese wheels, three layers were sampled diagonally across the cheese: under the cheese rind, an intermediate section and the cheese core. After two different ripening periods (9 and 18 months), the cheese samples were analysed using traditional culture dependent and culture independent methods. Milk samples were dominated by mesophilic and psychrophilic bacterial counts. Thermophilic bacteria (Lactobacillus helveticus) were found in high amounts in cooked whey and natural whey starter cultures. After 9 months of ripening, lactic acid bacteria (LAB) counts were higher than those after 18 months. Furthermore, the LAB numbers in the cheese core was lower than those under the rind or in the intermediate section. The main LAB species isolated from milk (Lactococcus lactis, Pediococcus pentosaceus, Streptococcus uberis and Lactococcus garvieae) were not found in the corresponding cheeses. Some differences were observed in the species composition among the three cheese sections. Microbiota under the rind and in the intermediate section was similar and dominated by Lactobacillus paracasei and Lactobacillus rhamnosus. The core, after 18 months of ripening, was characterized by a total absence of LAB. In each sample, all LAB were genotypically grouped and the different biotypes were subjected to several technological tests indicating that some non-starter LAB (NSLAB) displayed technological features that are favorable for the production of Grana Trentino cheese.
Microorganisms influence on quality and flavor of cheese
2016
For this study information about microorganism in cheese and their effect on the final product was gained from science databases, e.g. Science Direct, Web of Science and Prima. The taxonomic structures of microbial communities in cheese can be studied by culture-dependent and culture independent methods. Some problems with production of cheese are early and late gas formation and growth of pathogens. Although these problems can be counteracted by sanitation, adding nitrate, microfiltration, bactofugation, lower water activity and by lowering the pH, they can give the cheese inferior quality. Biological hazards can be avoided by good sanitation. For a good shelf-life cheese, techniques such as fermentation and pasteurization are important. Lactic acid bacteria are very important for flavor development and toxin-producing bacteria can in combination with resistant bacteria be used to control flavor development.
PLoS ONE, 2013
Microbial communities play an important role in cheese ripening and determine the flavor and taste of different cheese types to a large extent. However, under adverse conditions human pathogens may colonize cheese samples during ripening and may thus cause severe outbreaks of diarrhoea and other diseases. Therefore in the present study we investigated the bacterial community structure of three raw ewe's milk cheese types, which are produced without the application of starter cultures during ripening from two production sites based on fingerprinting in combination with next generation sequencing of 16S rRNA gene amplicons. Overall a surprisingly high diversity was found in the analyzed samples and overall up to 213 OTU 97 could be assigned. 20 of the major OTUs were present in all samples and include mostly lactic acid bacteria (LAB), mainly Lactococcus, and Enterococcus species. Abundance and diversity of these genera differed to a large extent between the 3 investigated cheese types and in response to the ripening process. Also a large number of non LAB genera could be identified based on phylogenetic alignments including mainly Enterobacteriaceae and Staphylococcacae. Some species belonging to these two families could be clearly assigned to species which are known as potential human pathogens like Staphylococcus saprophyticus or Salmonella spp. However, during cheese ripening their abundance was reduced. The bacterial genera, were identified at a relative low level and only in selected samples. Overall the microbial composition of the used milk and the management of the production units determined the bacterial community composition for all cheese types to a large extend, also at the late time points of cheese ripening.