Moisture sorption characteristics of freeze-dried, osmo-freeze-dried, and osmo-air-dried cherries and blueberries

摘要

Equilibrium moisture contents (EMC) of freeze-dried, osmo-freeze-dried, and osmo-air-dried sweet cherries ('Bing') and highbush blueberries ('Bluecrops') at 10, 25, and 40℃ were determined by equilibrating samples to eight different humidities.Moisture sorption isotherms of cherries and blueberries displayed characteristics typical of high-sugar foods with crossing points at 0.4 to 0.8 water activity (a{sub}w) depending on temperature. Fitting of five sorption models (modified Henderson,Chung-Pfost, Halsey, Oswin, and Guggenheim-Anderson-de Boer) to data showed that the modified Henderson equation predicted isotherms with the smallest standard error of moisture content and mean relative percent error values. None of the equationsdescribed the EMC data adequately for the entire range of ERH. The modified Henderson equation was found to give a good fit at a{sub}w 0.8.