ABSTRACT
ABSTRACT: Despite the fact that cold storage and modified atmosphere techniques have already been studied for fresh cut Star fruit, little has been done considering the whole fruit. Besides that, each cultivar has its peculiarities, so the efficiency of combined postharvest treatments should be studied. The objective of this study was to evaluate the effect of polyvinyl chloride (PVC), 8.5 µm thick and low-density polyethylene (LDPE), 33 µm thick associated with cold storage (10 ± 1 °C and 5 ± 1 °C / 85 ± 5% RH) on the conservation of 'Malasia' Star fruit. Storage at 25 oC maintained Star fruit overall quality, regardless of the film type, up to four days. The weight loss was higher in fruit packed with PVC, but this fact was not noticed by the sensory analysis. The storage in 5 and 10 oC did not caused chilling injury but fruit presented retention of yellow color development and firmness reduction; these aspects were positively assessed by the sensory analysis. The film type did not influence the conservation of the fruit. The storage at 5 and 10 °C, regardless of the package film, prolonged 'Malasia' star fruit shelf life up to 16 days, followed by two days at 25 °C.
RESUMO: Apesar das técnicas de armazenamento refrigerado e atmosfera modificada já terem sido estudadas para carambolas processadas, pouco foi feito considerando a fruta inteira. Além disso, cada cultivar possui peculiaridades, dessa forma a eficiência dos tratamentos pós-colheita combinados deve ser estudada. O objetivo deste trabalho foi avaliar o efeito do cloreto de polivinila (PVC), 8,5 µm de espessura e polietileno de baixa densidade (PEBD), 33 µm de espessura associados ao armazenamento refrigerado (10 ± 1 °C e 5 ± 1 °C / 85 ± 5% de UR) na conservação da carambola Malasia. O armazenamento a 25 °C manteve a qualidade da carambola, independentemente do tipo de filme, até quatro dias. A perda de massa foi maior nos frutos embalados em PVC, mas esta não foi percebida pela análise sensorial. As temperaturas de armazenamento de 5 e 10 °C não causaram dano de frio, mas os frutos apresentaram retenção no desenvolvimento da coloração amarela e na redução da firmeza; esses aspectos foram avaliados positivamente na análise sensorial. O tipo de filme não influenciou a conservação do fruto. O armazenamento a 5 e 10 °C, independente do filme da embalagem, prolongou a vida útil da carambola 'Malasia' até 16 dias, seguido por dois dias a 25 °C.
ABSTRACT
The relationships between fungal growth and ergosterol content and between aflatoxins B1 and B2 production and ergosterol content were verified in corn grains. In the first experiment, fungal growth and ergosterol content were monitored during incubation of corn grains presenting water activities of 0.85aw and 0.92aw at 25§C over a period of 18 days. For the Taiúba variety, the fungi growth and ergosterol content increased more rapidly for 0.92aw than 0.85aw. Maximum ergosterol levels were 2.8 and 4.6 µg/g, respectively, for 0.85aw and 0.92aw. For the Cargill hybrid 606, a more pronounced increase in fungal growth was verified just at the end of the incubation period, mainly for 0.92aw when an acentuated increase in ergosterol content was also observed. Maximum ergosterol levels detected were 1.6 µg/g and 5.8 µg/g, respectively, for 0.85aw and 0.92aw. There was a significant correlation between ergosterol content and log of CFU g-1 for 0.92aw but not for 0.85 aw. In the second experiment, samples of corn grains of the Taiúba variety at 0.87aw and 0.95aw were inoculated with a toxigenic Aspergillus flavus strain and incubated at 25§C. Ergosterol levels reached maximum values of 12.1 and 73.4 µg/g, respectively, for 0.87aw and 0.95aw. In both water activities, content aflatoxin B1 followed the same trend as ergosterol. For the aflatoxin B2 this trend was not observed. Ergosterol assay appears to be a useful test to measure fungal growth and to indicate the possibility of aflatoxin production in corn grains.