Moisture sorption and thermodynamic properties of safflower petals and tarragon

Kaya, Sevim; Kahyaoğlu, Talip

doi:10.1016/j.jfoodeng.2005.10.009

Cited by 54 publications

(36 citation statements)

References 34 publications

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“…As the equilibrium moisture content increases, the sites available for water sorption decrease, resulting in lower values of net isosteric heat (Tsami et al 1990). Similar results have been reported for the foodstuffs in literature (Delgado and Sun 2002;Kaymak-Ertekin and Gedik 2004;Kaya and Kahyaoglu 2007;Rosa et al 2010).…”

Section: Net Isosteric Heat Of Sorptionsupporting

confidence: 90%

“…Once again, the differential entropy of desorption is higher than the corresponding adsorption value, at constant equilibrium moisture content. The differential entropy data displays a strong dependence on equilibrium moisture content as stated by Kaya and Kahyaoglu (2007). gives the parameters T β and ΔG β (Eq.…”

Section: Differential Entropymentioning

confidence: 95%

“…The net Isosteric heat of sorption is defined as the isosteric heat of sorption minus the latent heat of the pure water vaporisation. It can be computed from experimental sorption isotherm data using the Clausius-Clapeyron equation in the form (Kaya and Kahyaoglu 2007;Singh et al 2011;Chenlo et al 2011):…”

Section: Isosteric Heat Of Sorptionmentioning

confidence: 99%

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Thermodynamic analysis of sorption isotherms of cassava (Manihot esculenta)

et al. 2012

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Sorption isotherms of cassava were determined experimentally using a static gravimetric method at 30, 45 and 60°C and within the range of 0.10-0.90 water activity. At a constant water activity, equilibrium moisture content decreased with increasing temperature. The equilibrium moisture content increased with increasing water activity at a given temperature. The experimental results were modelled using seven sorption models using non-linear regression technique. Results demonstrated that the GAB model adequately predicted equilibrium moisture content of cassava for the range of temperatures and water activities studied. The thermodynamic functions such as net isosteric heat of sorption, differential entropy of sorption, net integral enthalpy and entropy were evaluated to provide an understanding of the properties of water and energy requirements associated with the sorption behaviour. Net isosteric heat and differential entropy decreased with increasing equilibrium moisture content. The net integral enthalpy decreased while net integral entropy increased with increasing equilibrium moisture content. Net integral entropy was negative in value. All thermodynamic functions were adequately characterised by a power law model. The point of maximum stability was found between 0.053 and 0.154 kg water/kg db for cassava.

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Section: Net Isosteric Heat Of Sorptionsupporting

confidence: 90%

Section: Differential Entropymentioning

confidence: 95%

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Thermodynamic analysis of sorption isotherms of cassava (Manihot esculenta)

et al. 2012

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“…Thermodynamic functions such as heat of vaporization (differential heat of sorption), net isosteric heat of sorption, and differential entropy are readily calculated from moisture sorption isotherms. The endpoint to which food must be dehydrated for a stable product with optimal moisture content, and the theoretical minimum amount of energy needed to remove water to a certain level of moisture content from the food can be determined from this information (14).…”

Section: Introductionmentioning

confidence: 99%

Moisture Sorption and Thermodynamic Properties of Vacuum-Dried Capsosiphon fulvescens Powder

Zuo

Rhim

Lee

2015

JFN

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ABSTRACT:The moisture sorption isotherms of vacuum-dried edible green alga (Capsosiphon fulvescens) powders were determined at 25, 35, and 45 o C and water activity (aw) in the range of 0.11∼0.94. An inversion effect of temperature was found at high water activity (＞0.75). Various mathematical models were fitted to the experimental data, and Brunauer, Emmett, and Teller model was found to be the most suitable model describing the relationship between equilibrium moisture content and water activity (＜0.45). Henderson model could also provide excellent agreement between the experimental and predicted values despite of the intersection point. Net isosteric heat of adsorption decreased from 15.77 to 9.08 kJ/mol with an increase in equilibrium moisture content from 0.055 to 0.090 kg H2O/kg solids. The isokinetic temperature (T) was 434.79 K, at which all the adsorption reactions took place at the same rate. The enthalpy-entropy compensation suggested that the mechanism of the adsorption process was shown to be enthalpy-driven.

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“…green instant tea powder (Sinija and Mishra, 2008), black and green tea leaves (Ghodake et al, 2007), Chenopodium ambrosioides L. leaves (Jamali et al, 2006), Mentha crispa L. leaves (Park et al, 2002), saffl ower (Carthamus tinctorius L.) petals and tarragon (Artemisia dracunculus L.) (Kaya and Kahyaoglu, 2007), and bitter orange leaves (Mohamed et al, 2005).…”

mentioning

confidence: 99%

Modelling the moisture sorption isotherms of Roselle (Hibiscus sabdariffa L.) in the temperature range of 5-35 °C

Langová¹,

Jaisut²,

Thuwapanichayanan³

et al. 2013

Acta Univ. Agric. Silvic. Mendelianae Brun.

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Brunensis, 2013, LXI, No. 6, pp. 1769-1777 Water sorption tests of Roselle (Hibiscus sabdariff a L.) carried out under laboratory conditions are presented together with mathematical analyses of the moisture sorption isotherms (MSI's). Moisture equilibrium data for adsorption and desorption of water from Roselle powder were investigated at near ambient air temperatures in the range of 5 and 35 °C and water activity (Aw) ranging from 0.11 to 0.97. The manometric method has been used for water sorption tests. Models for MSI's are exponential equations. Coeffi cients of determination are 0.998 and 0.996 (for adsorption and desorption at 5 °C, respectively), 0.998 and 0.999 (for adsorption and desorption at 20 °C, respectively), and 0.998 and 0.999 (for adsorption and desorption at 35 °C, respectively). The equilibrium moisture content (EMC) of Roselle samples increased with an increase of Aw at a constant temperature both for adsorption and desorption. Adsorption curve equates to desorption curve at higher temperatures of tests carried out. Critical values of EMC of samples tested corresponding to the Aw equal to 0.6 were between 13.401% moisture content wet basis (MC w.b.) and 15.934% MC (w.b.) for moisture adsorption and desorption, respectively. These values are useful for storing conditions optimisation from point of view microorganisms grow and structural changes analyses. Crystal structure changes were observed during adsorption and desorption in the microscope, too. It was found out glass transition in dependence on the water content of samples tested.water activity, equilibrium moisture content, hysteresis, prediction, grow of microorganisms, glass transition Roselle (Hibiscus sabdariff a L.) belongs to the family Malvaceae. It originated in India and it is widely distributed in tropical and subtropical regions as a potential new food crop of considerable economic potential. Roselle is a short-day annual erect shrub and can grow to a height of 1-3 m, depending on the species. Its calyces have been suggested for the production of so drinks, Roselle tea, jam, juices, and natural food colourants (Chen et al., 2005;Chang et al., 2012). The extracts of calyces and leaves of Roselle show a signifi cant antihyperlipidemic activity (Ochani and D'Mello, 2009).Roselle calyx (Fig. 1) is usually harvested at high MC (w.b.), 85%. Therefore, drying is an important postharvest treatment prior to reduce the MC and to increase the shelf life. Moreover, the main purpose of drying the products is to minimize packaging requirements, to prolong the shelf life and to reduce shipping weights (Vengaiah and Pandey, 2007). Tab. I shows the chemical composition of Roselle calyces (Babalola et al., 2001).

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Moisture sorption and thermodynamic properties of safflower petals and tarragon

Cited by 54 publications

References 34 publications

Thermodynamic analysis of sorption isotherms of cassava (Manihot esculenta)

Thermodynamic analysis of sorption isotherms of cassava (Manihot esculenta)

Moisture Sorption and Thermodynamic Properties of Vacuum-Dried Capsosiphon fulvescens Powder

Modelling the moisture sorption isotherms of Roselle (Hibiscus sabdariffa L.) in the temperature range of 5-35 °C

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