Curvas de equilíbrio higroscópico do cacau.

Abstract

The equilibrium moisture contents of cocoa were obtai ned in desorption phase covering a temperature range of 10°C to 35°C and a range of to relative humidities. The kernels were held inside hermetic glass containers with different sa tured salt solutions by small iron baskets. The Amineo-Aire conditioning unit was used to guarantee constant temperature. An electromagnetic set up was used to provide a swing motion of the basket with the kernels to allow the equklibrium mois ture contents were attained faster than with the static me thod. Equilibrium moisture equation proposed by Henderson, Chung-Pfost, Harkins-Jura and Smith were extended to model the desorption experimental moisture content data. The equa tion constants were obtained trhough a non linear regression analysis, Gauss-Newton method. Henderson's equation was considered to model desorpti on isotherms better than other equation. In agreement with other researchers it was verified that the equilibrium moistu re content increases with a relative humidity rise and when temperature decreases. It also verified that bigger decrease in temperature causes greater increase in equilibrium moistu re content.