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Equilibrium moisture characteristics of dehydrated food constituents as studied by a modified inverse gas chromatographic method
Author(s) -
Lagoudaki Maria,
Demertzis Panagiotis G
Publication year - 1994
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740650115
Subject(s) - chromatography , moisture , chemistry , gas chromatography , inverse gas chromatography , inverse , mathematics , organic chemistry , geometry
Computerised inverse gas chromatography was used to study the combined effects of moisture and temperature on the water sorption of potato starch, egg albumin and wheat gluten. A moisture increase resulted in typical BET‐II sorption isotherms. The water sorption isotherms of the three food constituents determined at 22, 30, 37 and 45°C showed that water sorption is favoured at low temperatures. A comparison between the computerised inverse gas chromatographic and the static gravimetric methods at 30°C showed that the former was faster and that the sorption isotherms of the two methods correlated well. BET, GAB, Freundlich, Chung‐Pfost, Smith and ‘Local’ isotherm models were tested to fit the data. Goodness of fit, standard deviation and applicable range of water activity ( a w ) indicated that GAB and ‘Local’ isotherm models could explain the data well over a wide a w range to 0.80. The heats of sorption of the three substrates were also calculated.