Experimental Determination and Modeling of Sorption Isotherms of Tropical Fruits: Banana, Mango, and Pineapple

Abstract

Sorption isotherms of banana, mango, and pineapple have been experimentally found at 40, 50, and 60 C by use of the salt method for a range of water activities from 0.056 to 0.85. The sorption capacity of these fruits increases with the temperature for a given water activity. The experimental curves have been simulated by the GAB and BET models. The BET model ensures a better representation of the experimental results for water activity lower than 0.35 with maximum deviation of 1.0, 1.5, and 2.0 kgwÁkgdm À1 for respectively banana, mango and pineapple. On the contrary, the GAB model enables the representation of the whole desorption isotherms and the estimation of the water content corresponding to monolayer saturation and of the isosteric heat of sorption. It also takes into account the temperature effect. The isosteric sorption heat of the three studied products are deduced from experimental results and empirical correlations are proposed leading to a satisfactorily representation.

Thermodynamic analysis of sorption isotherms of cassava (Manihot esculenta)

“…The air relative humidity is fixed by contact with saturated salts solution whose water vapour pressure at a given temperature is perfectly known. This method is commonly used for product sorption isotherms determination (Kouhila et al 2001;Lahsani et al 2003;Talla et al 2005;Yazdani et al 2006;Brett et al 2009;Singh et al 2011) and is recommended by the COST 90 project (Wolf et al 1985).…”

“…Relevant work has been carried out on sorption isotherms characteristics of foodstuffs (Mir and Nath 1995;Ayranci 1995;Myhara et al 1998;Tsami et al 1999;Ahouannou et al 2000;Talla et al 2001;Lahsani et al 2003;Talla et al 2005;Kaur et al 2006;Yazdani et al 2006;Vishwakarma et al 2007;Jain et al 2010;Jagadish et al 2010;Chenlo et al 2011).…”

Sorption isotherms and moisture sorption hysteresis of intermediate moisture content banana

“…The equations of BET and GAB provide the monolayer moisture content, and can be considered to be the most useful ones for determining the optimum moisture conditions for good storage stability, especially for dehydrated foods (Arslan and Togrul, 2006). GAB, Henderson (1952), modified Henderson, modified Halsey equation and modified Oswin equation were reported to have fitted well plantain or banana's equilibrium moisture content data over 10-70% relative humidity range (plantain, a member of the banana family, a starchy and low in sugar variety) (Ajibola, 1986;Johnson and Brennan, 2000;Phoungchandang and Woods, 2000;Talla et al, 2005).…”

Modelling of the sorption isotherms and determination of the isosteric heat of split pistachios, pistachio kernels and shells

“…Its value in drying equilibrium should be considered at the end of the drying process, since it has a magnitude equal to the latent heat of vaporisation (Talla et al 2005). (1 -a w ) (1 -a w + Ca w ) BET (Brunauer et al 1940) w = -A (T ln a w ) Halsey (Halsey 1948)…”