Adesão de Staphylococcus aureus em superfícies e condições do processamento de produtos cárneos
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Data
2010-07-30
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Universidade Federal de Viçosa
Resumo
Em função da demanda por alimentos mais saudáveis e convenientes, existe a necessidade crescente do desenvolvimento de modelos matemáticos que descrevam o comportamento dos micro-organismos sob diversas condições. Este trabalho teve como objetivo avaliar o efeito de diferentes combinações de temperatura, pH, concentração de NaCl, concentração de NaNO2 e tempo de contato, aplicadas simultaneamente, na adesão de Staphylococcus aureus em superfícies de aço inoxidável (AIN), poliuretano (PU) e cloreto de polivinila (PVC). Os experimentos foram conduzidos de acordo com o delineamento de Box-Behnken, sendo portanto, escolhidos três níveis de cada variável independente estudada. Os níveis inferiores, centrais e superiores de cada variável foram designados como -1, 0 e +1. Foram ensaiadas 40 combinações entre os níveis dos cinco fatores de interesse e seis repetições referente a combinação no ponto central para estimativa da variância experimental. O programa MINITAB® 13 foi utilizado nas análises estatísticas. S. aureus aderiu, em determinadas condições, nas superfícies de AIN, PU e PVC. Em todas as superfícies estudadas os níveis extremos dos fatores proporcionaram menor capacidade de adesão do micro-organismo à superfície, sendo a condição ótima de adesão próxima ao ponto central estudado. Foi observado que a adesão de S. aureus às superfícies torna-se maior com o aumento do tempo de contato. Nenhuma das concentrações de NaNO2 influenciaram a adesão de S. aureus (p > 0,05). As condições utilizadas na fabricação de produtos cárneos fermentados como baixo pH alcançado em curto intervalo de tempo e manutenção do produto em baixas temperaturas, além de diminuir a proliferação de S. aureus neste produto podem impedir que esse micro-organismo inicie o processo de adesão sobre as superfícies de AIN, PU e PVC. Os altos valores de coeficiente de determinação (R2) demonstraram a adequação do modelo quadrático em explicar a influência das variáveis independentes na resposta. Em superfície de AIN o modelo respondeu por 80,5 %, em PU 78,2 % e em PVC 80,6 %. Os fatores bias (fb) calculados para as superfícies de AIN, PU e PVC foram 1,05, 1,05 e 1,08 respectivamente, enquanto os fatores exatidão (fe) foram 1,18, 1,16 e 1,82 respectivamente. Os modelos gerados no presente estudo foram classificados como bons e aceitáveis e, deste modo, podem ser utilizados para predição da adesão de S. aureus sobre as superfícies de AIN, PU e PVC.
Depending on the demand for healthier foods and convenience, the researchers acknowledge that there is a growing need for mathematical models that describe the behavior of micro-organisms under different conditions. This study aimed to evaluate the effect of different combinations of temperature, pH, NaCl concentration, concentration of NaNO2 and contact time, applied simultaneously, in the adhesion of Staphylococcus aureus on surfaces of stainless steel (STS), polyurethane (PU) and polyvinyl chloride (PVC). The experiments were conducted in accordance with the Box-Behnken design, being therefore, selected three levels of each independent variable studied. The lower, central and upper levels of each variable were designated as -1, 0 and +1. 40 combinations between the levels of five factors and six replicates of interest regarding the combination at the center point to estimate the experimental variance were tested. The Minitab® 13 program was used in the statistical analysis. S. aureus was able to adhere, under certain conditions, on the surfaces of STS, PU and PVC. On all studied surfaces the extreme levels of the factors provided lower adhesion ability of the microorganism to the surface, being the best condition of theadhesion close to the studied central point. It was observed that the adherence of S. aureus to the surfaces becomes more pronounced as the contact time increases. None of the NaNO2 concentrations used in this study were significant in the adhesion of S. aureus (p > 0,05). The results indicated that the conditions used in the manufacture of fermented meat products such as low pH achieved in a short period of time and the packaging of the product at low temperatures, besides decreasing the proliferation of S. aureus in this product may prevent the micro-organism to start the adhesion process on the surfaces of STS, PVC and PU. The high coefficients values of determination (R2) demonstrated the suitability of the quadratic model to explain the influence of independent variables in the response. On the surface of STS the model accounted for 80.5 %, 78.2 % in PU and in PVC 80,6 %. The bias factors (bf) calculated for the surfaces of STS, PU and PVC were 1.05, 1.05 and 1.08 respectively, while the accuracy factors (af) were 1.18, 1.16 and 1.82 respectively. The models generated in this study were classified as good and acceptable and thus can be used to predict the adhesion of S. aureus on the surfaces of STS, PU and PVC.
Depending on the demand for healthier foods and convenience, the researchers acknowledge that there is a growing need for mathematical models that describe the behavior of micro-organisms under different conditions. This study aimed to evaluate the effect of different combinations of temperature, pH, NaCl concentration, concentration of NaNO2 and contact time, applied simultaneously, in the adhesion of Staphylococcus aureus on surfaces of stainless steel (STS), polyurethane (PU) and polyvinyl chloride (PVC). The experiments were conducted in accordance with the Box-Behnken design, being therefore, selected three levels of each independent variable studied. The lower, central and upper levels of each variable were designated as -1, 0 and +1. 40 combinations between the levels of five factors and six replicates of interest regarding the combination at the center point to estimate the experimental variance were tested. The Minitab® 13 program was used in the statistical analysis. S. aureus was able to adhere, under certain conditions, on the surfaces of STS, PU and PVC. On all studied surfaces the extreme levels of the factors provided lower adhesion ability of the microorganism to the surface, being the best condition of theadhesion close to the studied central point. It was observed that the adherence of S. aureus to the surfaces becomes more pronounced as the contact time increases. None of the NaNO2 concentrations used in this study were significant in the adhesion of S. aureus (p > 0,05). The results indicated that the conditions used in the manufacture of fermented meat products such as low pH achieved in a short period of time and the packaging of the product at low temperatures, besides decreasing the proliferation of S. aureus in this product may prevent the micro-organism to start the adhesion process on the surfaces of STS, PVC and PU. The high coefficients values of determination (R2) demonstrated the suitability of the quadratic model to explain the influence of independent variables in the response. On the surface of STS the model accounted for 80.5 %, 78.2 % in PU and in PVC 80,6 %. The bias factors (bf) calculated for the surfaces of STS, PU and PVC were 1.05, 1.05 and 1.08 respectively, while the accuracy factors (af) were 1.18, 1.16 and 1.82 respectively. The models generated in this study were classified as good and acceptable and thus can be used to predict the adhesion of S. aureus on the surfaces of STS, PU and PVC.
Descrição
Palavras-chave
S. aureus, Adesão, Indústria de produtos cárneos, Aço inoxidável, Poliuretano, PVC, S. aureus, Adhesion, Meat products industry, Stainless steel, Polyurethane, PVC
Citação
TETTE, Patrícia Amaral Souza. Adhesion of Staphylococcus aureus on different surfaces and conditions used in the processing of meat products. 2010. 85 f. Dissertação (Mestrado em Ciência de Alimentos; Tecnologia de Alimentos; Engenharia de Alimentos) - Universidade Federal de Viçosa, Viçosa, 2010.