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Effect of Temperature on the Moisture Sorption Isotherms and Water Activity Shift of Two Dehydrated Foods
Author(s) -
LABUZA T. P.,
KAANANE A.,
CHEN J. Y.
Publication year - 1985
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1985.tb13409.x
Subject(s) - sorption , moisture , water activity , chemistry , thermodynamics , vapour pressure of water , salt (chemistry) , vapor pressure , monolayer , water vapor , water content , analytical chemistry (journal) , chromatography , adsorption , organic chemistry , biochemistry , physics , geotechnical engineering , engineering
The water activity (a w ) of eight salt solutions was determined at three temperatures (25, 30, 45°C) using a pressure transducer‐vapor pressure manometer. The a w s of the salts showed a decrease with increasing temperature, which was explained with the help of a thermodynamic equation. This is opposite to the increase in a w with increase in temperature for foods. Moisture sorption data for fish flour and cornmeal were obtained at 25–65°C. The Guggenheim‐Anderson‐deBoer model was evaluated and shown to be comparable to the Brunauer‐Emmett‐Teller model for prediction of the monolayer. Product was equilibrated at different a w s at 25°C then subsequently shifted to 30°C and 45°C in a sealed chamber. The resultant a, change, measured on the Kaymont‐Rotronics, was predictable from the isotherm at each temperature using the Clausius Clapeyron relationship.