Determinação de indicadores básicos de higiene e estirpes estafilocócicas enterotoxigênicas presentes na produção de queijo Serra da Canastra tradicional, Minas Gerais, Brasil

Brazilian Journal of Microbiology (2006) 37:545-550

ISSN 1517-8382

545

ENTEROXIGENIC STAPHYLOCOCCUS SPP. AND OTHER MICROBIAL CONTAMINANTS

DURING PRODUCTION OF CANASTRA CHEESE, BRAZIL

Beatriz M. Borelli1; Elaine G. Ferreira1; Inayara C. A. Lacerda1; Deise A. Santos2; Luiz S. Carmo1; Ricardo S. Dias2;

Maria Crisolita C. Silva2; Carlos A. Rosa1*

1 Departamento de Microbiologia, ICB, CP. 486, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil;

2Laboratório de Enterotoxinas. Fundação Ezequiel Dias, Belo Horizonte MG, Brazil

Submitted: January 03, 2006; Returned to authors for corrections: March 23, 2006; Approved: October 13, 2006

ABSTRACT

Canastra cheese is produced from raw cow’s milk, and it is made at the farmhouse level using artisanal

procedures and natural starters. The aim of this work was to determine the main hygienic-sanitary indicators

and enterotoxigenic staphylococcal strains present during the manufacturing of traditional cheese of Serra da

Canastra region, Minas Gerais state, Brazil. Samples from 10 farms were studied, and they included: water

employed in the process, raw milk, natural starters, cheese curd before salting and cheese after five days of

ripening. All water samples exhibited faecal coliform contamination above the maximum acceptable value

recommended by Brazilian standards. Pseudomonas aeruginosa and sulfite-reducing clostridia were also

isolated from the water samples. In five samples of raw milk faecal coliform were above the limits allowed by the

Brazilian legislation. The counts of Staphylococcus spp. in milk were between <2.0 to 4.9 log.cfu.ml-1. The

counts of microbiological indicators were higher in natural starters and curd. High levels of faecal and total

coliform, as well as molds, were found in the cheese samples. In all cheeses analyzed Staphylococcus spp. were

found in levels above 5.0 log.cfu.g-1. The enterotoxins (SE) most frequently produced by Staphylococcus spp.

strains were SEB and SEC. A high number of coagulase negative Staphylococcus strains were also enterotoxin

producers. None of the samples contained Salmonella spp. or Listeria spp. These results point out a need for

improvements in the production process of the artisanal cheese produced at Serra da Canastra in Brazil.

Key words: Artisanal cheese, coliforms, Staphylococcus, enterotoxin

INTRODUCTION

Serra da Canastra cheese is traditionally made with raw cow’s

milk employing natural starters (indigenous lactic acid bacteria)

and commercial rennet. The cheeses produced in the region of

Serra da Canastra have been manufactured in a traditional

empirical manner for more than 200 years in Minas Gerais state,

Brazil (25). The natural starter used in its production is composed

by species of Lactobacillus, Lactococcus and Streptococcus,

with counts of approximately 8 log cfu.ml-1, and it is produced

by dropping whey from previous cheese covered with salt (B.

M. Borelli & C. A. Rosa, unpublished data). The production of

Canastra cheese is about 375.5 tons per month, being the main

*Corresponding Author. Mailing address: Departamento de Microbiologia, ICB, CP. 486, Universidade Federal de Minas Gerais, Belo Horizonte, MG,

31270-901 Brazil. Tel.: [phone]. E-mail: [e-mail]

economic activity of many families of the region (14).

Nevertheless, there is no standardization of the manufacturing

process, especially regarding time of coagulation, natural starter

used, pressing, salt and humidity in the final product. Thus, it is

possible to find Canastra cheeses in the market having different

and characteristic flavors and aromas.

As Canastra cheese is an artisanal product, the production

process does not follow safety standards regulary. Use of raw

milk, for example, is a cause for worry because it constitutes an

important source of pathogens such as Staphylococcus aureus,

Escherichia coli, Salmonella spp., Shigella spp., Listeria

monocytogenes, among others (6,16,20). The presence of S.

aureus and the possibility of staphylococcal toxin production

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Borelli, B.M. et al.

represent a potential risk for public health (3,4,17,22).

Staphylococcal enterotoxins (SEs) are a family of nine

thermostable, pepsin-resistant exoproteins forming a single chain

with a molecular weight ranging from 26,000 to 29,600 Da (10,17).

They are identifiable serologically and known as SEA, SEB,

SEC, SED, SEE, SEG, SEH, SEI and SEJ. Most staphylococcal

strains are able of producing one or more enterotoxins, which

are the cause of the gastrointestinal symptoms, that include

vomiting with or without diarrhea, observed