Efeito da microbiota endógena e da nisina sobre Listeria sp. e Staphylococcus aureus em queijo Minas artesanal do Serro

• Autor(a) principal: Pinto, Maximiliano Soares
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/404
• topic: Queijos artesanais; Patógenos em queijos; Microbiologia de queijos; Artesanal cheese; Cheese pathogens; Cheese microbiology; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::TECNOLOGIA DE ALIMENTOS

Traditional Minas cheese is commonly produced by milk obtained from herds located in mountains. In addition, Traditional cheese is manufactured in small properties situated mainly in four regions of state of Minas Gerais: Serra da Canastra, Serro, Cerrado and Araxá. Because cheese is produced with raw milk, it can be impropriated for consumption, since it can contain pathogenic microorganisms. Studies carried out in laboratories show the inhibitory effect of lactic acid bacteria against Listeria sp. and Staphylococcus aureus. This work aimed to evaluate the antagonistic effect of endogenous bacteria and natural starter of Traditional Minas cheese against Listeria innocua during 60 days of ripening. Besides, it was also evaluated the effect of addition of 100 and 500 IU.ml-1 of nisin, added to milk against the behavior of S. aureus and also its influence on fracturability, elasticity, gumminess, chewiness, cohesiveness and physicochemical characteristics (moisture, fat content, salt, pH, aw, ripening extension and depth) of Traditional Minas cheese during 60 days of ripening. The antagonistic effect of endogenous microbiota and of natural stater it was not enough to eliminate L. innocua present in the cheese in three different concentrations, along the ripening time. The behavior of L. innocua during the ripening was similar, independent of the initial concentration used in the present work. These results show that the absence of Listeria sp. In Traditional Minas cheese observed in many other studies probably is related to the absence of this bacteria in milk. The reduction of S. aureus was proportional to the nisin doses used. The nisin was effective in the reduction of population of S. aureus between the inoculation up to the obtaining of the mass. Both doses of nisin tested showed bactericidal effect against S. aureus during the period of milk inoculation until the process to obtain the mass. The cheese treated with 500 IU.ml-1 of nisin showed higher salt levels in comparison with those treated with 100 IU.ml-1 of nisin and the control samples. The cheeses treated with nisin showed lower levels of ripening. It was not observed diference (p ≥ 0.05) in moisture, fat, pH and aw between nisin treatements and the control samples after 60 days of ripening. Also, in relation to the texture profile, it was not observed difference (p ≥ 0.05) between nisin cheese and control cheese samples, except for elasticity.