Authors: Francisco Chenlo Ramón Moreira Diego M Prieto María D Torres
Publish Date: 2009/08/13
Volume: 4, Issue: 8, Pages: 1497-1504
Abstract
The desorption isotherms of chestnut flour and chestnut starch were determined at different temperatures 20°C 35°C 50°C and 65°C using gravimetric method Desorption isotherms of potato starch were also determined in order to establish a comparison against desorption isotherms of chestnut starch Several saturated salt solutions were selected to generate different water activities in the range of 009 to 091 Obtained desorption isotherms were of type II according to Brunauer’s classification Threeparameter Brunauer–Emmett–Teller and Guggenheim–Anderson–de Boer GAB models satisfactorily fitted the experimental data for all systems studies although the last one can be considered better based on obtained statistical parameters and because it is applicable in a broader water activity range The average monolayer moisture content kilograms per kilogram db calculated by GAB model was 0059 ± 0007 for chestnut flour 0103 ± 0021 for chestnut starch and 0060 ± 0028 for potato starch The net isosteric sorption heat calculated by means of Clausius–Clapeyron equation decreased when moisture content increased The maximum values of net isosteric sorption heat kilojoules per mole were approximately 275 for chestnut flour 160 for chestnut starch and 330 for potato starch in the range of temperature from 20°C to 50°C
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