The influence of temperature on rehydration and sorption properties of freeze-dried strawberriesReport as inadecuate

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Croatian journal of food science and technology, Vol.1 No.1 July 2009. -

The aim of this work was to investigate the influence of heating shelf temperature on selected physical properties of freeze-dried strawberries. Frozen strawberries were freeze-dried at heating shelf temperature of 10, 30, 50 and 70°C for 24 hours.

Rehydration, adsorption rate and sorption isotherms were determined for freeze-dried strawberries. With increase the temperature of heating shelves in the range 10-50°C, rehydration capacity was increased. After 30 minutes of the rehydration process there was a decrease in water content, which is probably connected with changes in structure. Sorption isotherms were included to II isotherms type and have a sigmoidal shape characteristic for most food products. For the mathematical description Peleg’s model was used. For freeze-dried strawberries obtained in the range from 10 to 50°C isotherms have the same courses. Increase of temperature to 70°C resulted in obtaining the lowest water content in the water activity range from 0.113 to 0.648. There is a statistically significant influence of temperature of heating shelf on water vapour sorption for freeze-dried strawberries. For fruit freeze-dried in 30°C there was the highest water vapour sorption rate.

strawberries; freeze-drying; water sorption; kinetic; rehydration

Author: Agnieszka Ciurzyńska - ; Warsaw University of Life Sciences, Faculty of Food Sciences, Warszawa, Poland A. Lenart - ; Warsaw Uni



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