Abstract:
Data of water desorption on different food products were analysed from the point of view of the BET theory. A plot of log C against 1/T as used for the independent evaluation of E1‐EL and the pre‐exponential a1b2/b1a2, in the expression for the constant C of the BET theory. It was found that a1b2/b1a2, may range from 10−3 to 10−6 and the E1 ‐ EL values are correspondingly much higher than usual. An equation has been obtained within the framework of the BET theory for the dependence of the net heat of desorption on moisture content. In the present analysis the variation of the monolayer value with temperature is considered by means of a simple empirical equation. The results are compared with the heats of desorption calculated directly by the Clausius‐Clapeyron equation. Copyright © 1984, Wiley Blackwell. All rights reserved
Referencias:
- Berezin, G.I., Kiselev, A.V., Coverage on the basis of BET theory assumptions. Dependence of heat capacity of adsorbate on surface (1966) Journal of Colloid and Interface Science, 22, pp. 161-164
- Bettelheim, F.A., Volman, D.H., Pectic substances—water. II. Thermodynamics of water vapor sorption (1957) Journal of Polymer Science, 24, pp. 445-454
- Brunauer, S., Emmett, P.H., Teller, E., Adsorption of gases in multimolecular layers (1938) Journal of the American Chemical Society, 60, pp. 309-319
- Bull, H.B., Adsorption of water vapor by proteins (1944) Journal of Chemical Physics, 66, pp. 1499-1507
- Bushuk, W., Winkler, C.A., Sorption of water vapor on wheat flour, starch and gluten (1957) Cereal Chemistry, 34, pp. 73-85
- Cassie, A.B.D., Multimolecular absorption (1945) Transactions of the Faraday Society, 41, pp. 450-464
- Day, D.L., Nelson, G.L., Desorption isotherms for wheat (1965) Transactions of the American Society of Agricultural Engineers, 8, pp. 293-297
- Iglesias, H.A., Chirife, J., Isosteric heats of water vapor sorption on dehydrated foods. II. Hysteresis and heat of sorption comparison with BET theory (1976) Lebensmittel Wissenschaft und Technologie, 9, pp. 123-127
- Iglesias, H.A., Chirife, J., Lombardi, J.L., An equation for correlating equilibrium moisture content in foods (1975) Journal of Food Technology, 10, pp. 289-297
- Kemball, C., Schreiner, G.D.L., The determination of heats of adsorption by the Brunauer‐Emmett‐Teller single isotherm method (1950) Journal of the American Chemical Society, 72, pp. 5605-5607
- Masuzawa, M., Sterling, C., Gel‐water relationships in hydrophilic polymers: thermodynamics of sorption of water vapor (1968) Journal of Applied Polymer Science, 12, pp. 2023-2032
- Mohlin, U.B., Gray, G.D., Gas chromatography on polymer surfaces: adsorption on cellulose (1974) Journal of Colloid and Interface Science, 47, pp. 747-777
- Roman, G.N., Urbicain, M.J., Rotstein, E., Moisture equilibrium in apples at several temperatures: experimental data and theoretical considerations (1982) Journal of Food Science, 47, pp. 1484-1488
- Suárez, C., Aguerre, R.J., Viollaz, P.E., Analysis of the desorption isotherms of rough rice (1983) Lebensmittel Wissenschaft und Technologie, 16, pp. 176-179
- Volman, D.H., Simons, J.W., Seed, J.R., Sterling, C., Sorption of water vapor by starch. Thermodynamics and structural changes for dextrin, amylose and amylopectin (1960) Journal of Polymer Science, 46, pp. 355-364
- Wolf, W., Spiess, W.E.L., Jung, G., The water vapor sorption isotherms of foodstuffs (1973) Lebensmittel Wissenschaft und Technologie, 6 (3), pp. 94-96
Citas:
---------- APA ----------
AGUERRE, R.J., SUÁREZ, C. & VIOLLAZ, P.E.
(1984)
. Calculation of the variation of the heat of desorption with moisture content on the basis of the BET theory. International Journal of Food Science & Technology, 19(3), 325-331.
http://dx.doi.org/10.1111/j.1365-2621.1984.tb00355.x---------- CHICAGO ----------
AGUERRE, R.J., SUÁREZ, C., VIOLLAZ, P.E.
"Calculation of the variation of the heat of desorption with moisture content on the basis of the BET theory"
. International Journal of Food Science & Technology 19, no. 3
(1984) : 325-331.
http://dx.doi.org/10.1111/j.1365-2621.1984.tb00355.x---------- MLA ----------
AGUERRE, R.J., SUÁREZ, C., VIOLLAZ, P.E.
"Calculation of the variation of the heat of desorption with moisture content on the basis of the BET theory"
. International Journal of Food Science & Technology, vol. 19, no. 3, 1984, pp. 325-331.
http://dx.doi.org/10.1111/j.1365-2621.1984.tb00355.x---------- VANCOUVER ----------
AGUERRE, R.J., SUÁREZ, C., VIOLLAZ, P.E. Calculation of the variation of the heat of desorption with moisture content on the basis of the BET theory. Int. J. Food Sci. Technol. 1984;19(3):325-331.
http://dx.doi.org/10.1111/j.1365-2621.1984.tb00355.x