Lucimara Blumer

Gamma irradiation in the control of pathogenic bacteria in refrigerated ground chicken meat

ABSTRACT: This work evaluated the effect of gamma radiation on reducting the population of Staphylococcusaureus , Escherichia coli and Salmonella typhimurium in ground chicken breast stored under refrigeration. Theexperiment included a control and 4 doses of gamma radiation (2.0, 4.0, 6.0 and 8.0 kGy) along with 5 periodsof storage under refrigeration (1, 7, 14, 21 and 28 days). Samples of ground chicken breast were inoculatedwith Staphylococcus aureus (ATCC 14458), Escherichia coli (ATCC 11105) and Salmonella typhimurium (ATCC0626), irradiated at temperatures between 4 and 8 o C and stored under refrigeration (5 o C) for 28 days. Theincreased radiation dose and period of storage under refrigeration caused a reduction of Staphylococcus aureus ,Escherichia coli and Salmonella typhimurium populations in the ground chicken breast. Mean radiation D valuesdetermined for Staphylococcus aureus and Escherichia coli were 0.41 and 0.72 kGy, respectively. Gammairradiation was an effective treatment for chicken meat conservation because the radiation dose of 6.0 kGy keptthe ground chicken breast within the microbiological limits established by the Brazilian legislation, for up to 28days under refrigeration.Key words: gamma irradiation, pathogenic bacteria, chicken meat, refrigeration

Sinergia da radiação ionizante e do aquecimento na vida de prateleira da uva Itália

The storage behavior of grapes cv. Italia, immersed in hot water and irradiated with different radiation doses was studied through their chemical analysis (soluble solids, titrable acidity and pH) and sensorial analysis (overall appearance and firmness). Samples of 500g of grapes were used in 4 replicates per treatment . Part of them were immersed in hot water (50°C for 5 min) before irradiation and part was irradiated at room temperature (22°C - 25°C). The irradiation was performed using a Cobalto-60 source, type Gammabeam-650. The dose rate was 1.89 kGy/h. The radiaton doses were 0 (control), 1, 2, 3, 4 and 5 kGy. After irradiation the samples were placed in cartoon boxes and stored under refrigeration at 6°C - 8°C. The chemical and sensorial analysis were performed after 60 days of storage. The titrable acidity and the pH increased significantly with increasing radiation doses. The heat and gamma radiation treatments, combined or not, did not extended the grape shelf life.

Efeito da radiação gama nas características físico-químicas e microbiológicas do queijo prato durante a maturação

O Prato, queijo de pasta lavada, e um dos mais populares do Brasil e deve ser maturado para atingir as caracteristicas de sabor, aroma e textura. O presente trabalho teve por objetivo estudar o efeito da radiacao gama no periodo de maturacao do queijo Prato. Dois periodos para a irradiacao foram testados, no 1o dia e no 15o dia de maturacao. Os queijos Prato foram irradiados com as doses 0 (controle), 1, 2, 3 e 4kGy nos periodos citados, em irradiador de cobalto-60 Gammabeam 650 da Atomic Energy do Canada, com taxa de dose 0,9696kGy/h e armazenados a 10-12oC e ± 85% UR, por 60 dias. As analises fisico-quimicas e microbiologicas foram realizadas de 15 em 15 dias ate completar 60 dias de maturacao. Atraves dos resultados observou-se que, com o aumento da dose de radiacao, diminuiu a flora microbiana do queijo e, que a irradiacao retardou a maturacao, conforme se aumentou a dose. Isto se deve provavelmente, pela destruicao das bacterias laticas.

EFEITOS DO TRATAMENTO COMBINADO DE IRRADIAÇÃO GAMA E REFRIGERAÇÃO NO CRESCIMENTO DE LEVEDURA (Saccharomyces cerevisiae Hansen) EM SUCO DE LARANJA

The effect of gamma radiation and of low temperatures was studied on yeast growth in orange juice. Concentrated orange juice (65° Brix) was diluted to 10,5° Brix and inoculated with comercial biological yeasts. The samples were irradiated with doses of 0.0 (control), 1.0, 1.5, 2.0, 2.5, 5.0 and 7.5 kGy (Cobalt-60), with a 2.83 kGy/h dose rate. All the samples were stored at 0°, 5° and 25°C for periods of 1; 7; 14; 21; 30; 60 and 90 days of storage. Combined treatment of 1 kGy and refrigeration at 0°C was effective for orange juice conservation for 90 days of storage. The dose of 2.5 kGy, was sufficient to conserve the juice for 90 days of storage at 5°C. At 25°C only the two highest radiation doses (5.0 and 7.5 kGy) were effective to control yeast growth in orange juice.

Chemical Elements in Organic and Conventional Sweet Oranges

This work focuses on the determination of chemical elements in sweet oranges of variety Valencia produced under organic and conventional systems using instrumental neutron activation analysis and inductively coupled plasma mass spectrometry. The distribution of chemical elements was variable among the fruit parts with usually higher concentrations of Br, Ca, Ce, K, La, Na, Rb, and Sc in the peel. However, K, Na, and Rb also presented high values in the juice samples, while Fe and Zn were higher in the seeds. Differences between organic and conventional oranges were found for Br and Cu.

Radiação gama na redução da carga microbiana de filés de frango

Neste trabalho estudou-se o efeito da radiacao gama na destruicao dos microrganismos presentes em files de frango armazenados sob refrigeracao. Um dos possiveis fatores de deterioracao da carne de frango e a atividade microbiana. A irradiacao e um processo de conservacao de alimentos atraves da eliminacao de microrganismos. O delineamento experimental foi em blocos casualizados com 5 fatores (periodos de armazenamento) e 5 niveis (doses de radiacao), com 3 repeticoes por tratamento. As amostras de file de frango foram irradiadas com doses de 0,0; 2,0; 4,0; 6,0 e 8,0kGy e em seguida armazenadas sob refrigeracao (± 5oC) por 1, 7, 14, 21 e 28 dias. A contagem total dos microrganismos foi realizada por plaqueamento em profundidade em meio de cultivo PCA. As amostras nao irradiadas permitiram um acrescimo de dois ciclos logaritmicos na contagem microbiana ao longo dos vinte e oito dias de armazenamento (de 105 para 107UFC/g). As amostras irradiadas com dose de 2,0kGy permitiram acrescimo de um ciclo logaritmico durante os vinte e oito dias de armazenamento (de 103 para 104UFC/g). As doses de radiacao de 4,0; 6,0 e 8,0kGy reduziram a populacao microbiana a niveis de 102UFC/g no vigesimo primeiro dia e 101UFC/g no vigesimo oitavo dia de armazenamento. A irradiacao pode ser um processo eficiente para a reducao da carga microbiana de files de frango porque a dose de radiacao de 4,0kGy foi suficiente para manter os files de frango refrigerados com uma populacao microbiana de 101UFC/g ate vinte e oito dias de armazenamento.