Equilibrium Isotherm Equations to Represent Moisture Sorption on Starch

Boki, Keito; Ohno, S.

doi:10.1111/j.1365-2621.1991.tb14654.x

Cited by 25 publications

(22 citation statements)

References 13 publications

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“…Crapiste and Rotstein (1982) noted that it is also extremely difficult to measure and control static experiments at high relative humidities, because serious moisture fluctuations occur around the dew point. Our static sorption data are in good agreement with those reported by Van den Berg et a1 (1975) and Boki and Ohno (1991) for potato starch. They are also in general agreement with those of Bull (1944) for egg albumin and with those of Bushuk and Winkler (1957) concerning wheat gluten.…”

Section: Resultssupporting

confidence: 94%

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Equilibrium moisture characteristics of dehydrated food constituents as studied by a modified inverse gas chromatographic method

Lagoudaki

Demertzis

1994

J Sci Food Agric

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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-I1 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,) indicated that GAB and 'Local' isotherm models could explain the data well over a wide a, range to 0.80. The heats of sorption of the three substrates were also calculated.

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Section: Resultssupporting

confidence: 94%

“…Boki and Ohno (1991) proposed that the greater the values of the constants of the Chung-Pfost equation the where A and B are constants (Table 4) Three replicates.…”

Section: Smith Equationmentioning

confidence: 99%

Equilibrium moisture characteristics of dehydrated food constituents as studied by a modified inverse gas chromatographic method

Lagoudaki

Demertzis

1994

J Sci Food Agric

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“…The Henderson model is a semi-empirical model derived on thermodynamic procedures. The large value of the constants for the Henderson model indicated a possible microporous or energetically heterogeneous structure for chitosan adsorption [49]. In the Smith model [27] the adsorbed amount on the surface is subdivided into a bound and a normally condensed fraction.…”

Section: Discussionmentioning

confidence: 99%

Understanding the adsorption mechanism of chitosan onto poly(lactide-co-glycolide) particles

Guo

Gemeinhart

2008

European Journal of Pharmaceutics and Biopharmaceutics

114

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Polyelectrolyte-coated nanoparticles or microparticles interact with bioactive molecules (peptides, proteins or nucleic acids) and have been proposed as delivery systems for these molecules. However, the mechanism of adsorption of polyelectrolyte onto particles remains unsolved. In this study, cationic poly(lactide-co-glycolide) (PLGA) nanoparticles were fabricated by adsorption of various concentrations of a biodegradable polysaccharide, chitosan (0-2.4 g/L), using oil-in-water emulsion and solvent evaporation techniques. The particle diameter, zeta-potential, and chitosan adsorption of chitosan coated PLGA nanoparticles confirmed the increase of polyelectrolyte adsorption. Five adsorption isotherm models (Langmuir, Freundlich, Halsey, Henderson and Smith) were applied to the experimental data in order to better understand the mechanism of adsorption. Both particle diameter and chitosan adsorption increased with chitosan concentration during adsorption. A good correlation was obtained between PLGA-chitosan nanoparticle size and adsorbed chitosan on the surface, suggesting the increased particle size was primarily due to the increased chitosan adsorption. The zeta-potential of chitosan-coated PLGA nanoparticles was positive and increased with chitosan adsorbed until a maximum value (+55 mV) was reached at approximately 0.4-0.6 g/L; PLGA nanoparticles had a negative zeta-potential (−20 mV) prior to chitosan adsorption. Chitosan adsorption on PLGA nanoparticles followed a multilayer adsorption behavior, although the Langmuir monolayer equation held at low concentrations of chitosan. The underlying reasons for adsorption of chitosan on PLGA nanoparticles were thought to be the cationic nature of chitosan, high surface energy and microporous non-uniform surface of PLGA nanoparticles.

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“…The agreement of these models with the experimental data shows variations depending on the water activity range and the type of food (Ayranci et al 1990;Boki & Ohno 1991;Palou et al1997).…”

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confidence: 50%

Influence of chemical composition and environmental conditions on the textural properties of dried fruit bars

Özilgen¹

2011

Czech J. Food Sci.

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Ozilgen S. (2011): Influence of chemical composition and environmental conditions on the textural properties of dried fruit bars. Czech J. Food Sci., 29: 539-547.The influences of the composition, environmental humidity, and temperature on the stability of dried fruit bars during storage were investigated. Sultana bars were chosen to represent similar types of fruit bars. The moisture sorption isotherms and textural stability of sultana bars with and without glucose and maltodextrin additives were determined at 20°C and 40°C using the standard static gravimetric method. The shape of all of the isotherms was found to be typical of high sugar foods and could be explained by four different models. Additives and storage temperatures affected the monolayer moisture content, equilibrium moisture content, and the textural stability of the sultana bars during storage at the same water activity. The relationship between the loss of stiffness and water activity had a sigmoid shape and was explained by Fermi's equation. This paper fills an important gap with that which does not exist in a large number of sorption behaviour publications available in the literature. It presents real data explaining the true mechanism of textural change during storage with both water activity and glass transition theories for high sugar fruit pastes. The information obtained from this study may help the food producers, who make high sugar containing dried fruit products, to create better textural and sensory properties, and may also help to predict the storage stability and packaging requirements.

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Equilibrium Isotherm Equations to Represent Moisture Sorption on Starch

Cited by 25 publications

References 13 publications

Equilibrium moisture characteristics of dehydrated food constituents as studied by a modified inverse gas chromatographic method

Equilibrium moisture characteristics of dehydrated food constituents as studied by a modified inverse gas chromatographic method

Understanding the adsorption mechanism of chitosan onto poly(lactide-co-glycolide) particles

Influence of chemical composition and environmental conditions on the textural properties of dried fruit bars

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