RESUMO
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.
O efeito da radiação gama e baixas temperaturas foi estudado no crescimento de Saccharomyces cerevisiae em suco de laranja. O suco concentrado de laranja (65°Brix) foi diluído a 10,5°Brix e inoculado com levedura comercial. As amostras foram irradiadas com doses de 1,0, 1,5, 2,0, 2,5, 5,0 e 7,5 kGy (Cobalto 60), a uma taxa de dose de 2,83 kGy/h. Todas as amostras foram armazenadas a 0°, 5° e 25°C, por 1, 7, 14, 21, 30, 60 e 90 dias. O tratamento combinado de 1 kGy e refrigeração a 0°C foi efetivo para a conservação do suco de laranja por 90 dias de armazenamento. A dose de 2,5 kGy foi suficiente para conservar o suco de laranja por 90 dias de armazenamento a 5°C. A 25°C, somente as doses mais altas (5 e 7,5 kGy) foram efetivas no controle do crescimento da levedura no suco de laranja.
RESUMO
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.
O efeito da radiação gama e baixas temperaturas foi estudado no crescimento de Saccharomyces cerevisiae em suco de laranja. O suco concentrado de laranja (65°Brix) foi diluído a 10,5°Brix e inoculado com levedura comercial. As amostras foram irradiadas com doses de 1,0, 1,5, 2,0, 2,5, 5,0 e 7,5 kGy (Cobalto 60), a uma taxa de dose de 2,83 kGy/h. Todas as amostras foram armazenadas a 0°, 5° e 25°C, por 1, 7, 14, 21, 30, 60 e 90 dias. O tratamento combinado de 1 kGy e refrigeração a 0°C foi efetivo para a conservação do suco de laranja por 90 dias de armazenamento. A dose de 2,5 kGy foi suficiente para conservar o suco de laranja por 90 dias de armazenamento a 5°C. A 25°C, somente as doses mais altas (5 e 7,5 kGy) foram efetivas no controle do crescimento da levedura no suco de laranja.