Resumo

AYALA-APONTE, ALFREDO. ADSORPTION ISOTHERMS AND ISOSTERIC HEAT ESTIMATION IN CASSAVA FLOUR. Rev.Bio.Agro [online]. 2011, vol.9, n.1, pp.88-96. ISSN 1692-3561.

Moisture adsorption isotherms of cassava flour were determined using a gravimetric static method at 20,25, 30 and 35°C in the range of water activity from 0.111 to 0.901. The experimental values of sorption were fitted by the models of GAB, BET, Oswin, Smith, Henderson and Chung, and Pfost. The isosteric heat of sorption (Q_st) was determined by the Clausius-Clapeyron equation. The isotherms obtained were sigmoid shape (Type II). The equilibrium moisture content (CHE) decreased with increasing temperature to a constant value of water activity. The sorption models of GAB, Oswin and Smith were found to be the most suitable for description of the sorption data. The Q_st decreased with increasing CHE obtaining a maximum and a minimum between 118.84 and 45.20 kJ/mol for moisture between 5 and 35 (g water / g db) respectively.

Palavras-chave : Cassava flour; Adsorption isotherms; Mathematic models; Isosteric heat.

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