Enthalpy–entropy compensation in sorption phenomena of starch materials

McMinn, W.A.M.; Al-Muhtaseb, Ala’a H.; Magee, T.R.A.

doi:10.1016/j.foodres.2004.11.004

Cited by 111 publications

(120 citation statements)

References 24 publications

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“…Also, as T1>Thm, the processes can be considered as enthalpy driven, which implies that only one mechanism of reaction is followed by all members of the reaction series. This further suggests that the microstructure of the flour was stable and does not undergo any changes during moisture adsorption (McMinn et al, 2005). The result obtained agrees with that reported for sweet potato flour by Fasina (2006).…”

Section: Enthalpy-entropy Compensation Theorysupporting

confidence: 90%

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Adsorption isotherms and thermodynamics properties of water yam flour

Owo

Adebowale

Sobukola

et al. 2017

Quality Assurance and Safety of Crops & Foods

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SummaryAdsorption isotherms of water yam flour were determined by static gravimetric method of saturated salt solutions in the range of water activities between 0.11 and 0.96 and at temperatures of 25, 35 and 45 °C. The experimental sorption data was fitted to five models: Guggenheim-Anderson-De Boer (GAB), Peleg, Iglesias-Chirife, Exponential and Oswin and the differential enthalpy and entropies were determined. Equilibrium moisture contents decreased with increase in temperature at all the water activities studied. Peleg model gave the best fit for the sorption isotherm of water yam flour. Monolayer moisture content values estimated from the GAB-model were found to decrease with increases in temperature. The differential enthalpy and entropy decreased with increases in moisture content. The isokinetic temperature was 371.32 K and the compensation theory was satisfied.

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Section: Enthalpy-entropy Compensation Theorysupporting

confidence: 90%

“…Examining the values of ∆G from Equation 8 above revealed that the sorption process was spontaneous. McMinn et al (2005) had previously reported spontaneous sorption isotherms for starchy materials.…”

Section: Enthalpy-entropy Compensation Theorymentioning

confidence: 99%

Adsorption isotherms and thermodynamics properties of water yam flour

Owo

Adebowale

Sobukola

et al. 2017

Quality Assurance and Safety of Crops & Foods

View full text Add to dashboard Cite

show abstract

“…Thus, entropy characterizes or defines the degree of order or randomness existing in the water-sorbent system and aids interpretation of processes such as dissolution, crystallization and swelling. Free energy (ΔG) indicates the affinity of the sorbent for water, and its sign provides a criterion as to whether water sorption is a spontaneous (-ΔG) or non-spontaneous process (+ΔG) (McMinn et al, 2005).…”

Section: Resultsmentioning

confidence: 99%

Moisture sorption characteristics of microalgae Spirulina platensis

Oliveira

Rosa

Moraes

et al. 2009

Braz. J. Chem. Eng.

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-In recent times, the microalgae Spirulina platensis has been used as a functional ingredient in several food applications; its process involving drying and storage steps. Moisture equilibrium data for adsorption isotherms of microalgae Spirulina were investigated at 10, 20 and 30°C and for desorption, at 40, 50 and 60°C, using the gravimetric static method. The experimental data were analyzed by GAB and BET models. The GAB equation showed the best fitting to the experimental data with R² ≈ 99% and MRE < 10%. The water surface area values calculated by GAB and BET models were very similar. The isosteric heats were determined by application of Clausius-Clapeyron equation to sorption isotherms obtained from the best-fitting equation. The isosteric heat and the entropy of desorption isotherm presented similar behavior, with a sharp change in an equilibrium moisture content of 10%. The enthalpy-entropy compensation theory was applied to the isotherms, indicating that they are enthalpy-controlled.

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“…In Equation 10 ∆H int is the molar equilibrium enthalpy of sorption (integral enthalpy, J/mol) at a constant potential surface, also called diffusion pressure or spreading pressure (J/m 2 ), defined by Equation 11 (McMinn et al, 2005):…”

Section: Thermodynamic Properties Of Water Sorptionmentioning

confidence: 99%

Study of thermodynamic water properties and moisture sorption hysteresis of mango skin

Souza

Alves

Vieira

et al. 2015

Food Sci. Technol (Campinas)

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The equilibrium moisture content for adsorption and desorption isotherms of mango skin was determined using the static gravimetric method at temperatures of 20, 26, 33, 38 and 44 o C in the 0.056 to 0.873 water activity range. Both sorption curves show a decrease in equilibrium moisture content as the temperature increasing. The hysteresis effect was observed at constant water activity. The Guggenheim, Anderson, and de Boer (GAB) model presented the best fitting accuracy among a group of models and was used to determine the thermodynamic properties of water sorption. Integral enthalpy and integral entropy areas showed inverted values for the adsorption and desorption isotherms over the wide range of water activity studied. These values confirm, in energetic terms, the difference between adsorption and desorption isotherms observed in the hysteresis phenomenon. Finally, the Gibbs free energy revealed that the sorption process was spontaneous for both sorption isotherms.Keywords: agricultural waste; gravimetric method; integral properties; modelling; water content.Practical Application: This work presents information about the hysteresis characteristics of mango skin as well as their thermodynamic properties of water sorption. The information given in this study can be used for processing, storage, and packaging of this agro-waste. In addition, the combination of classical and modern methodologies is useful for determining the best stability conditions over a range of water activity and equilibrium moisture content.

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Enthalpy–entropy compensation in sorption phenomena of starch materials

Cited by 111 publications

References 24 publications

Adsorption isotherms and thermodynamics properties of water yam flour

Adsorption isotherms and thermodynamics properties of water yam flour

Moisture sorption characteristics of microalgae Spirulina platensis

Study of thermodynamic water properties and moisture sorption hysteresis of mango skin

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