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vol. 11, nr. 1 (2008)
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Sorption features of corn and rice crisps
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Millena Ruszkowska , Aneta Ocieczek, Piotr Palich
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Department of Organization of Tourist and Hotel Services, Maritime Academy, ul. Morska 83, 81-225 Gdynia |
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vol. 11 (2008), nr. 1,
pp. 183-193
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abstract:
The aim of the study was to determine sorption features of extruded products on the example of plant food concentrates, rice and corn crisps. Measurements of sorption in disintegrated and non-disintegrated material were made with a static method on the basis of isotherms analysis, and with a dynamic method by determination of kinetics and rate of the vapour adsorption process of disintegrated products, in an environment with a water activity aw = 0.07, 0.55, 0.69, 0.75, 0.85, 0.98, within 24 h of measurement. Sorption isotherms were determined in the range of water activity of aw = 0.07-0.98. The monomolecular layer capacity Vm and corresponding water activity and adsorption specific surface area were calculated from the BET equation. Vapour adsorption isotherms of studied crisps corresponded with type II in the Brunauer classification, and differences observed in sorption of disintegrated and non-disintegrated material were probably a result of disintegration, causing development of surface in the studied products. Higher monolayer capacity and sorption specific surface area in the adsorption process were achieved in disintegrated products. Course of curves of vapour adsorption kinetics and rate was conditioned by the environment water activity and the initial water content in the studied products. Results of the Smirnow-Kołmogorow conformity test at the significance level of a = 0.05 showed that differences between the equilibrium water content calculated from the adsorption kinetics and the one achieved from vapour adsorption process were not statistically significant.
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keywords:
sorption isotherms, specific surface area, sorption kinetics
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original in:
English
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