T. F. Machado

Avaliação da qualidade microbiológica de hortaliças minimamente processadas

A microbiota e um fator de grande importância na qualidade e conservacao de vegetais minimamente processados. Muitos microrganismos podem afetar adversamente a qualidade e a seguranca desses produtos, considerando que microrganismos patogenicos, que normalmente nao estariam presentes, passam a compor a microbiota contaminante decorrente do manuseio a que sao submetidos. Objetivou-se, neste trabalho, determinar a qualidade microbiologica de hortalicas, anterior e posteriormente ao processo de sanitizacao, como tambem o periodo final da vida-de-prateleira dos produtos sanitizados, avaliando-se a presenca de Listeria sp., Listeria monocytogenes e Salmonella sp. Foram analisadas amostras de agriao, alface, cenoura ralada, espinafre, repolho verde ralado e rucula minimamente processados. As amostras nao sanitizadas foram analisadas no dia da coleta, e as sanitizadas analisadas a 1, 5 e 8 dias apos o processamento, a fim de determinar a condicao microbiologica dos produtos. As hortalicas foram armazenadas sob temperatura de 5oC. Salmonella sp. foi detectada em 12,7% das amostras, enquanto L. monocytogenes nao foi encontrada em nenhuma delas, embora outras especies de Listeria tenham sido isoladas de alface e cenoura. A presenca de Salmonella sp. tornaram 16 amostras improprias para o consumo humano, de acordo com a RDC no 12.

The antimicrobial efficacy of Lippia alba essential oil and its interaction with food ingredients

The objective of this study was to evaluate the antimicrobial potential of Lippia alba essential oil (EOLa) and to investigate the effect of food ingredients on its efficacy. The antimicrobial potential of the oil was determined by the presence or absence of inhibition zones, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Escherichia coli, Listeria innocua, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella choleraesuis and Staphylococcus aureus. The effect of food ingredients and the pH on the antimicrobial efficacy of oil was assessed by monitoring the maximum growth rate of Listeria monocytogenes in model media. The model media included potato starch (0, 1, 5 or 10%), beef extract (1, 5, 3, 6 or 12%), sunflower oil (0, 5 or 10%) and TSB broth at pH levels of 4, 5, 6 or 7. The EOLa showed efficacy at all concentrations (50%, 25%, 6.25%, 3%, 1.5%, 0.8%, 0.4% and 0.2%) evaluated, against all bacterial species, Gram-positive and Gram-negative. The antimicrobial efficacy of EO was found to be a function of ingredient manipulation. Proteins and lipids had a negative impact on the oil effectiveness, indicating the protective action of both on the microbial specie tested. On the contrary, at the highest concentration of starch (10%), the lower rate growth of L. monocytogenes was detected, therefore indicating a positive effect of carbohydrates on the oil effectivenes. Regarding the pH, the studies showed that the rate of microbial growth increased with increasing pH. It was concluded that the use of EOLa is more effective control pathogenic and spoilage bacteria when applied to starchy foods under an acidic pH.

Seasonal variability of the antimicrobial activity of the essential oil of Lippia alba

Lippia alba e um arbusto da familia Verbenaceae, popularmente conhecida como erva-cidreira. Seu oleo essencial e citado com amplo espectro de atividade antimicrobiana, cuja eficacia varia em funcao da sua composicao, que sofre influencia de fatores bioticos e abioticos. O presente trabalho teve como objetivo, avaliar a eficacia antimicrobiana do oleo de folhas de L. alba, coletadas nas diferentes estacoes do ano, frente a microrganismos de importância em alimentos. O oleo, obtido por hidrodestilacao, foi testado contra culturas padroes de Pseudomona aeruginosa, Salmonella choleraesuis, Escherichia coli, Staphylococcus aureus, Listeria monocytogenes e Listeria innocua, utilizando as tecnicas de difusao em agar. Observou-se uma grande influencia das diferentes epocas de coleta na eficiencia do oleo, que variou em funcao de cada especie microbiana. No periodo dezembro - fevereiro, a melhor resposta foi frente a S. aureus. Para L. monocytogenes a maior eficacia do oleo ocorreu no periodo junho - agosto, enquanto que para L. innocua o oleo apresentou a mesma resposta em tres periodos do ano, diferenciando apenas no periodo compreendido entre marco e maio. A correlacao dos dados meteorologicos do ano de 2010 permite aferir, que as caracteristicas tipicas do periodo dezembro a fevereiro no municipio de Paraipaba-CE (altas temperaturas, longos periodos de insolacao e baixo indice de precipitacao pluiometrica) favoreceram a acao do oleo frente S. aureus. No periodo de junho a agosto, por sua vez, as condicoes da estacao potencializaram a acao do oleo contra L. monocytogenes e L. innocua.

Interferência da microbiota autóctone do queijo coalho sobre Staphylococcus coagulase positiva

High levels of microbial contamination, commonly found in animal origin foods and food processing environments, are able to hinder the growth in these products. In some contexts where lactic acid bacteria (LAB) are the normal dominant microbiota, such as in fermented food, Staphylococcus coagulase positive (SCP) colonises, persists and produces food poisoning. With the aim of verifying the interference of autochthonous microbiota encountered in Curd cheese over the presence of Staphylococcus aureus, 64 samples from 16 dairy were submitted to microbiological analysis to determine the levels of Microorganisms aerobes mesophilics (MAM), LAB and SCP. The results showed that the indigenous microbiota of the samples did not lead to inadequate growth, development and isolation of SCP, since this pathogen was detected even in samples with high levels of counts of AM and BAL.

Vegetal burgers of cashew fiber and cowpea: formulation, characterization and stability during frozen storage

This work aimed to obtain a vegetable burger from the cashew juice production residue (fiber) and cowpea that are two abundant materials in Northeast Brazil. Fiber was washed and pressed in an expeller for five times. Cowpea was soaked in water and, after skin removal, ground to obtain a paste. Hamburgers were made by mixing the cashew fiber, the cowpea paste, and the ingredients used in traditional burger recipes, then shaped and frozen. Four sensory tests were performed to define: (1) the need of cooking the cowpea paste with the other ingredients; (2) the fiber/paste proportion; (3) ingredients to enhance the sensory characteristics; (4) burger acceptance. The resultant formulation had 29.3% of cashew fiber, 29.3% of cowpea paste, 25.1% of tomato, 6.8% of onion, 5.3% of sweet pepper, 1.3% of garlic, 0.1% of black pepper, 0.2% of dehydrated parsley, 1.2% of salt and 1.4% of corn oil. The sensory acceptance was 7.8 in a 9-point hedonic scale. Proximate composition was 71.08% moisture, 2.07% ashes, 4.86% proteins, 1.19% lipids and 20.79% total carbohydrates. Stability was evaluated during frozen storage (-18 oC) for 180 days. In this period, acidity increased and pH and ascorbic acid decreased. As to color, a* and b* values increased, indicating that the burgers became more orange/brown. The burger was considered microbiologically safe and shelf-stable for at least 6 months.

VEGETAL BURGERS OF CASHEW FIBER AND TEXTURIZED SOY PROTEIN

Neste trabalho, avaliou-se a utilizacao da fibra de caju em associacao a proteina texturizada de soja para elaboracao de hamburguer vegetal. Foram estudados dois tratamentos para a reducao do tamanho da fibra (prensagem mecânica associada ou nao a maceracao enzimatica) e seu impacto nas carateristicas fisico-quimicas, aceitacao sensorial e estabilidade dos hamburgueres armazenados a -18oC, por 180 dias. As duas formulacoes dos hamburgueres apresentaram alto teor de umidade e carboidratos, e baixo teor de lipideos. A maceracao enzimatica da fibra resultou em produtos com menor umidade e mais duros. Durante o armazenamento dos hamburgueres, observaram-se reducao de pH e de acido ascorbico, e aumento de acidez, nao tendo sido observadas tendencias para os parâmetros de cor. Os hamburgueres estiveram dentro dos padroes microbiologicos da legislacao brasileira para o consumo humano, e as medias de aceitacao sensorial, dentro da zona de aceitacao durante todo o periodo de armazenamento. Conclui-se que, a inclusao de maceracao enzimatica ao processo de tratamento da fibra nao apresenta vantagens e que os hamburgueres obtidos de fibra de caju e proteina texturizada de soja podem ser consumidos ate seis meses de armazenamento congelado.

ELABORAÇÃO E CARACTERIZAÇÃO DE BLENDAS DE AMIDO FOSFORILADO COM QUITOSANA E PVA

The aims of this study were to produce films from phosphorylated starch/chitosan/PVA blends and evaluate their physicochemical properties. The film properties were dependent on the starch percentage in the blend. The infrared spectra of the blends showed the appearance of bands at 1716 and 1733 cm-1 (stretching C = O of PVA acetate residues) and 1556 cm-1 (amide II deformation of the chitosan) indicating the incorporation of these components into the blends. The films with high phosphorylated starch content showed low thermal and mechanical strength and high water absorption capacity while blends with higher content of chitosan and PVA showed good mechanical properties and low water vapor permeability. Films containing 40% and 20% starch showed excellent properties such as high water absorption capacity and biodegradability for use as bandages and agricultural films and also as a source of organic matter in soil.