Resumo

AYALA-APONTE, ALFREDO A.; SERNA COCK, LILIANA  e  RODRIGUEZ, GLORIA. MOISTURE DESORPTION ISOTHERMS IN YELLOW PITAHAYA (Selenicereus megalanthus). Rev.Bio.Agro [online]. 2012, vol.10, n.2, pp.135-143. ISSN 1692-3561.

Moisture desorption isotherms for yellow pitahaya fruits were studied at 15, 25, and 35°C using the gravimetric method for a 0.111-0.901 water activity range. Experimental values were adjusted by using the GAB, Henderson, Smith, Oswin y Chung y Fost models. The isosteric heat of adsorption (Qst) was determined using the Clausius-Clapeyron equation. The results showed that yellow pitahaya fruits exhibit type III adsorption isotherms and that the equilibrium moisture content (EMC) is temperature-dependent. For the same water activity value, the EMC decreased when temperature increased. The GAB model presented the best fit to the experimental values. The Qst dropped from 61.43 a 45.11 kJ/mol when the EMC increased from 0.08 to 0.56 g water/g dry matter, respectively.

Palavras-chave : Cactaceae; mathematical models; isosteric heat of sorption.

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