Avaliação da resistência térmica de Salmonella sp. em água de escaldagem do abate de suínos em função do pH e matéria orgânica

Orientador : Prof. Dr. Luciano dos Santos Bersot

Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Palotina, Programa de Pós-Graduação em Ciência Animal. Defesa: Palotina, 30/09/2015

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Resumo: In Brazil, as in many parts of the world, there are projects that aimed at the replacement of diesel with biodiesel in order to reduce the dependence of the energy on the non-renewable fossil fuels. Currently, there is great concern about biodieseldiesel blends at low temperatures. While the diesel has its cloud point (CP) around - 16 °C, in case biodiesel this transition may occur in a temperature range between 0 °C and 16 °C. Therefore, the addition of biodiesel can cause problems as the formation of sludge in storage tanks, transport, to impair performance in engines, among others. This project aims to evaluate the cloud point of mixtures of biodiesel with diesel by means of curves of solid-liquid equilibrium (ESL) obtained by differential scanning calorimetry (DSC). To this, were determined T-x phase diagrams of solid-liquid equilibrium of binary systems, pseudo-binary and ternary involving majority saturated esters found in biodiesel, ethyl palmitate, ethyl stearate and representative alkane of diesel, n-hexadecane. Samples of the each mixture are prepared in weight using the micro analytical balance (Perkin-Elmer AD6). The cloud point of mixtures was characterized by DSC 8500 with auto samp A escaldagem é uma das principais etapas do abate de suínos com o objetivo de reduzir grandes quantidades de micro-organismos patogênicos, como a Salmonella. Conhecer os fatores que afetam a sobrevivência da Salmonella na escaldagem é essencial para garantir a menor passagem deste micro-organismo para as etapas posteriores de abate. O objetivo desta dissertação foi avaliar a resistência térmica de Salmonella Typhimurium e Derby em condições similares à escaldagem de abate de suínos e com diferentes pH e concentrações de matéria-orgânica. Amostras de água de escaldagem foram coletadas antes do início, no meio e ao final do abate de um matadouro frigorífico. Foram realizadas análises físico-químicas para quantificação de matéria-orgânica, cloro, turbidez e pH. O pH das amostras foi ajustado em 4, 7 e 10 e divididas em tubos de ensaio para os testes de letalidade térmica que foram realizados em banho-maria a 62°C por 5 minutos. Houve elevação constante na concentração de matéria-orgânica durante o abate. Não foi observada diferença no tempo de redução decimal (valor-D) entre as concentrações de matéria orgânica. Em pH alcalino Salmonella foi mais sensível com valor-D cerca de 17% menor que em neutro. O sorotipo Derby foi mais resistente que o Typhimurium inicialmente, porém, no final de cinco minutos foram equivalentes. Houve uma redução média de aproximadamente 3,19 log UFC/mL de Salmonella e valor-D de 1,65 minutos. Conclui-se que a adoção de escaldagem com temperatura de 62°C por 5 minutos é eficaz, e a definição do parâmetro de renovação de água não foi relevante para melhorar a eficiência na eliminação de Salmonella. Palavras-chave: cal, calor, escaldagem, resistência, Salmonellaler (Perkin Elmer). These phase diagrams obtained, present the peritectic and eutectic points. All eutectic points occurred in ??1 ? 0,2. The experimental results showed that no significant difference in cloud point, if the mixture (binary, ternary and pseudo-binary) has a number equal or greater than 80% by weight of hexadecane. For lower amounts of hexadecane, the presence of ethyl palmitate resulted in a decrease in cloud point. This work again demonstrated the suitability of the technique used in this type of study and contributed clearly to a better understanding of the cloud point of biodiesel-diesel blends behavior. Key-words: Solid-liquid Equilibrium. Ethyl Palmitate. Ethyl Stearate. Hexadecane.

Abstract: The scalding is one the main steps of swine slaughtering in order to reduce great quantities of pathogenic microorganisms, like Salmonella. To know the factors that affect the Salmonella survival in scalding is essential to guarantee the smallest passage of this microorganism to further slaughtering steps. This paper's objective was to avail the thermic resistance of the Salmonella Typhimurium and Derby in similar condition to scalding of swine slaughtering and with different pH levels and organic matter concentration. Samples of scalding water were collected before the beginning, in the middle, and at the end of the slaughter in a slaughterhouse. Physicochemical analyses were made to quantify the organic matter, chlorine, turbidity and pH. The sample's pH was adjusted to 4, 7, 10 and divided test-tubes to thermic lethality tests that were made in water-bath at 62ºC for 5 minutes. There was constant rising in the organic matter concentration during the slaughter. It was not observed difference in the decimal reduction time (D-value) in the different levels of organic matter concentrations during the slaughter. In alkaline pH Salmonella was more sensible with approximately 17% lower D-value than when in neutral pH level. The serotype Derby was initially more resistant than the Typhimurium, however, by 5 minutes they were equivalent. There was an average reduction of approximately 3.19 log CFU/mL of Salmonella and D-value of 1.65 minutes. It was concluded that the adoption of scalding in temperatures of 62ºC by 5 minutes is effective, and the definition of the water renovation parameter was not relevant to enhance the Salmonella elimination efficiency. Keywords: lime, heat, scalding, resistance, Salmonella