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vol. 12, nr. 3 (2008)
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The effect of enzymaztic treatment on convective drying kinetics and dehydration properties of dried pumpkin, carrot and apples
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Dorota Konopacka, Witold Płocharski
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Research Institute of Pomology and Floriculture, ul. Pomologiczna 18, 96-100 Skierniewice |
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vol. 12 (2008), nr. 3,
pp. 699-711
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abstract:
The paper presents results of a study on drying kinetics and rehydration properties of enzymatically treated tissue of fruit and vegetable. Apple, carrot and pumpkin of different maturity were diced and soaked in water solutions of enzyme preparations of pectinase activity (20 g L-1, 2 min, 20°C). Just after the treatment, cubes were dried convectively (70C, 2 m s-1, 240 min) or frozen before freeze drying. It was found that use of enzyme preparations (active against specific components of plant tissue) apparently increased water loss rate. However, it did not reduce total drying time due to the necessity of evaporating the water absorbed during soaking. In the case of carrot, an increase of equilibrium water content was also noticed. Using enzymes of polygalacturonase activity (for apple) and of pectinlyase activity (for carrot) caused an increase of rehydration ability of freeze dried products. In the case of convectively dried material enzymatic treatment did not influence the reconstitution properties. Convectively dried pumpkin subjected to pectinlyase treatment was char-acterized with lower rehydratation ability than the control; in the case of freeze dried material water absorption was faster at the beginning, however at a later stage of hydration the tissue was falling apart. Depending on the kind and destination of dried product, the enzymatic treatment before processing can be useful for modification of physical properties of final product.
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keywords:
convective drying, freeze drying, drying rate, rehydration ratio
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original in:
Polish
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