Net isosteric heat of sorption in dried fruits

Tsami, E.

doi:10.1016/0260-8774(91)90022-k

Cited by 179 publications

(125 citation statements)

References 13 publications

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“…This behavior indicates a higher number of polar sites on the surface of BG during the desorption process, which involves greater binding energy compared to the adsorption process (Tsami, 1991). A similar behavior was observed by Benado & Rizvi (1985) for rice moisture sorption processes and by Al-Muhtaseb et al (2004) for the moisture sorption of potato starch, high-amylopectin starch, and high-amylose starch.…”

Section: Differential Thermodynamic Propertiessupporting

confidence: 56%

Thermodynamic properties of Buriti (Mauritia flexuosa) tree gum

Silva

Pena

2018

Food Sci. Technol

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Moisture adsorption and desorption isotherms from buriti tree gum (BG) were obtained at different temperatures (25 to 55 °C) in a water activity range of 0.1 to 0.9. The isotherms were classified as type OO. The hysteresis loop and moisture of the monolayer decreased as temperature increased and Halsey's equation proved able to predict with good precision the product's sorption isotherms in the conditions studied. BG's isosteric heats of moisture adsorption and desorption were close to the latent heat of vaporization of pure water for moisture levels above 30 g/100 g db and exponentially increased below that level. The enthalpy-entropy compensation theory and the isokinetic relationship were applied and indicated that BG's moisture adsorption and desorption processes are spontaneous. The integral sorption properties indicated that the increase in surface tension at BG's moisture sorption sites was more representative for the desorption process.Keywords: Mauritia flexuosa; isotherm; water sorption; enthalpy; entropy. Practical application:The thermodynamic properties of sorption processes of gum from buriti tree were determined. These parameters are important to establish drying and storage conditions for the product.

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Section: Differential Thermodynamic Propertiessupporting

confidence: 56%

Thermodynamic properties of Buriti (Mauritia flexuosa) tree gum

Silva

Pena

2018

Food Sci. Technol

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“…These values can be compared to pure water vaporisation heat (L) which is equal to 44.5 kJ . mol -1 at 25 o C. According to Tsami [39], positive values of sorption heat at low water content are mainly due to hydrogen bond importance in the mono-layer water molecule formation.…”

Section: Water Activitymentioning

confidence: 99%

Article

Hardy

Scher

Banon

2002

Lait

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-Water is often the main component of many food products and their stability strongly depends on water interactions with other molecules. In the case of dehydrated products and especially milk powders, their use properties (flow properties, keeping quality and reconstitution properties) are closely dependent on the modes of water binding to the other constituents (proteins and lactose in particular). The water relations of milk powders strongly depend on drying process conditions and on their composition. They are well represented by sorption isotherms. However, to understand some mechanical properties (flowing, caking) it is necessary to take into account the glassy transition phenomenon. The water activity concept, water vapour sorption isotherms and glassy transition are redefined. A brief presentation of methods for characterising water properties and measuring hydration is done. Finally, explanation of the mechanisms of lactose hydration and of its crystallographic changes allows the linking of the use properties of dairy powders to their manufacturing technology.

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“…Para valores pequeños de humedad (<0.1 kg.kg -1 base seca), los valores de q st (kJ.mol -1 ) son altamente negativos, lo que significa que la sorción es una reacción espontánea. De acuerdo con Tsami (1991), los valores más negativos de q st , indican un mayor Observando los resultados del ajuste del modelo de GAB, las isotermas para pulpa con aditivos presentan valores menores de humedad para la monocapa que la de pulpa pura.…”

Section: Materials Y Métodosunclassified