Shelf-life increase of fresh mushrooms Pleurotus sajor-caju using gamma radiation. / Aumento da vida útil de cogumelos Pleurotus sajor-caju in natura com aplicação de radiação gama

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The production and consumption of edible mushrooms has been increasing in the last years due to its nutritional composition and sensory quality. The irradiation of mushrooms has been used with the purpose of maintaining the fresh product characteristics during shelf-life. The present study evaluated the effect of different radiation doses on the conservation of mushrooms Pleurotus sajor-caju, through by chemical, physical, microbiological and sensorial parameters. The packaging consisted on polystyrene trays with 250 g of sample, wrapped in polyvinyl chloride (PVC). The mushrooms were irradiated with doses of 125, 250, 500 and 750 Gy in a Gammacell 220 type irradiator, and stored at 4±1ºC and 90% UR for 10 days. The proximate composition (moisture, crude fibre, total protein, total fat and ash), total soluble solids, pH, texture, color (L, a*, b*, Chroma and ho), enzymatic activity (polyphenoloxidase and peroxidase), microbiological (total coliform, Escherichia coli and total psychotropic bacteria) and sensory evaluation (color, taste and appearance) were determined in the 1st, 5th and 10th storage days. For the respiratory rate analysis, 30 g of sample were placed in jars and stored at 4±1ºC and 90% UR for 8 days. CO2 was analyzed every day using a gaseous chromatographer. The results were submitted to variance analysis and average test using the SAS statistical package. The total protein and total fat values did not differ significantly between treatments or storage periods, while the moisture, crude fibre and ash values differ between treatments and periods. The dose of 750 Gy darkness the mushroom in the last evaluation, and texture was better in control during the storage period. The color (L, a*), texture and proximate composition values did not differ significantly between treatments or storage periods. A significant increase was observed for soluble solids, b* and enzymatic activity values in all treatments at the end of the storage period. Values of polyphenoloxidase and peroxidase activities increased in the last day of evaluation in samples irradiated with 250 Gy. This fact may be a result of the water radiolysis process, since mushrooms have high water content. The dose of 125 Gy increased the respiratory rate of the samples until the 5th storage day in comparison to the other treatments, causing reduction in the product shelf-life. The samples irradiated with 250, 500 and 750 Gy had a reduction on the respiratory rate if compared with the control, so contributing to the maintenance of the postharvest quality during the storage. The samples which received 750 Gy obtained the best results in the microbiological analyses, with reduction of total coliform and psychotropic bacteria during the storage period. Sensory analyses showed that the control had higher scores for color, aroma and appearance attributes; they were above the acceptability limit until the last storage day. In general, the irradiated samples were accepted for the evaluated attributes until the 5th storage day; thus, establishing the shelf-life for irradiated mushrooms

ASSUNTO(S)

pleurotus sajor-caju irradiação conservation mushrooms irradiation conservação cogumelos pleurotus sajor-caju

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