This study examined the efficacy of potassium lactate and lactic acid to control Campylobacter sp. and psychrotrophic bacteria on chicken. The objectives of the two studies conducted were to determine the optimal combination of potassium lactate and lactic acid to inhibit Campylobacter sp. in a challenge study and to inhibit naturally occurring Campylobacter sp. and psychrotrophic bacteria in a shelf life study. Boneless, skinless chicken breasts were injected with three levels of potassium lactate (0,1.5,2%), in conjunction with four levels of lactic acid. Lactic acid was injected (0, 0.1, 0.2, 0.3%) as well as applied directly to the surface (0.1% of weight of chicken breast). The chicken breasts were surface inoculated with a mixture of Campylobacter sp. and sampled over a period of 28 days at 11oC. The greatest inhibition was found using 2% potassium lactate in conjunction with any level of lactic acid (injected) or 0.1% lactic acid (surface application). Results of this study indicate that potassium lactate and lactic acid can be used to control the growth and/or survival of Campylobacter sp. on boneless chicken breasts. The second study eliminated the 1.5% potassium lactate and 0.2% and 0.3% lactic acid treatments and chicken breasts were not inoculated with Campylobacter sp.. This 4oC shelf life study occurred over 32 days, testing for Campylobacter species, psychrotrophic bacteria, as well as testing for sensory perceptions of color and odor changes in the chicken. The most effective treatment was the 2% potassium lactate-0.1% lactic acid surface treatment, demonstrating the most inhibition against both target populations. This treatment also had the greatest impact upon the odor of the chicken breasts. This treatment had the greatest difference from control samples, which was achieved by the inhibition of spoilage organisms on the chicken breasts. / Master of Science

Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Campylobacter sp is recognized as one of the main causes of human gastroenteritis of food origin. Among the foods that circulate these microorganism, chicken is the meat most involved. Existent studies about the vertical transmission of Campylobacter sp are scarce and inconclusive. The aim of this study was to verify the vertical transmission of Campylobacter sp from heavy matrixes to the progeny. With the use of the traditional culture method, cloacal swabs of 279 heavy matrix samples were analyzed from the follow sits: 6 bed, 4 nest, 11 ovary and oviduct, 11 liver, spleen and heart and 11 intestine. In 11 cloacal swab samples polymerase chain reaction (PCR) was also performed, using the automated BAX® system. In progeny samples, the following were analyzed: 78 and 44 fresh eggs, disinfected and not disinfected, respectively, 12 infertile eggs, 45 unhatched eggs, 13 hatching environment samples, 121 meconium samples and 36 organ samples (heart, liver, spleen) and 36 intestines from one-day old chickens. The analyses were performed by the traditional culture method. In another 10 meconium samples, analysis was performed by the BAX® method. The positivity in the cloacal swab samples by the traditional culture method was 13.97% and by the BAX® methodology it was 54.54%. The bed samples, positivity was 83.33% and in the nest samples it was 0.25%. In matrix organs, Campylobacter sp was only isolated in 27.27% of samples and only in the intestines. There was no positivity in any of the samples of fresh eggs, infertile eggs, embryonic eggs, chicken organs or from the hatching environment. By the traditional culture method there was no positivity in the meconium, but with the use of the BAX® system, positivity was 80%. Although the physiological characteristics of the matrixes, the eggs and Campylobacter sp are favorable to the entry and survival of bacteria in the eggs, and consequently in the one-day old chickens, in this study, positivity in the progeny was only found with the use of the BAX® system. These findings suggest that further studies with the use of molecular techniques should be conducted to verify vertical transmission. / Campylobacter sp é reconhecida como uma das principais causas de gastroenterite humana de origem alimentar e dentre os alimentos veiculadores desses microrganismos, a carne de frango é a mais implicada. As pesquisas existentes sobre a transmissão vertical da Campylobacter sp são escassas e não conclusivas. O objetivo desse estudo foi verificar a transmissão vertical da Campylobacter sp de matrizes pesadas para a progênie. Utilizando o método de cultura tradicional, foram analisados suabes cloacais de 279 amostras matrizes pesadas, 6 de cama, 4 de ninho, 11 de ovário e oviduto, 11 de fígado, baço e coração e 11 de intestino. Em 11 amostras de suabe cloacal, também foi realizada a reação da polimerase em cadeia (PCR) utilizando o sistema automatizado BAX®. Em amostras da progênie foram analisadas: 78 e 44 ovos frescos desinfetados e não desinfetados, respectivamente, 12 ovos inférteis, 45 ovos não eclodidos, 13 amostras ambientais de nascedouro, 121 de mecônio e 36 amostras de órgãos (coração, fígado, baço) e 36 intestinos de pintainhos de um dia. As análises foram realizadas pelo método de cultura tradicional e em outras 10 amostras de mecônio, pelo método BAX®. A positividade em amostras de suabe cloacal pelo método de cultura tradicional foi de 13,97% e pela metodologia BAX® 54,54%. Nas de cama, a positividade foi de 83,33% e nas de ninho, 25%. Em órgãos de matrizes, Campylobacter sp foi isolada em 27,27% das amostras e somente em intestinos. Não houve positividade em nenhuma das amostras de ovos frescos, inférteis, ovos embrionados, órgãos de pintainhos ou ambiente de nascedouro. Pelo método de cultura tradicional, não houve positividade em mecônio, embora com o uso do sistema BAX® a positividade foi de 80%. Apesar das características fisiológicas das matrizes, dos ovos e da Campylobacter sp serem favoráveis à entrada e sobrevivência da bactéria nos ovos, e conseqüentemente, nos pintainhos de 1 dia de idade, nesse estudo, as positividades na progênie foram apenas encontradas com a utilização do sistema BAX®. Esses achados sugerem que outros estudos com utilização de técnicas moleculares devem ser aplicados para verificação da transmissão vertical. / Mestre em Ciências Veterinárias