Determination of desorption isotherms, latent heat and isosteric heat of pequi diaspore

Kelly A De Sousa,Bruno De S Carvalho,Osvaldo Resende

doi:10.1590/1807-1929/agriambi.v20n5p493-498

Kelly A De Sousa, Bruno De S Carvalho + Show 1 more

Open Access

https://doi.org/10.1590/1807-1929/agriambi.v20n5p493-498

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Abstract

ABSTRACT The objective was to determine water sorption isotherms of diaspores of pequi fruits in order to obtain information on the amount of water that this product desorbs at the temperatures of 10, 20, 30 and 40 °C and water activities from 0.20 to 0.89, adjusting different mathematical models to experimental data, and to determine its latent heat and isosteric heat. The equilibrium moisture content was obtained through the indirect static method, using the device Hygropalm Model Aw 1. The Modified Henderson model was the one that best fitted the data and was selected to predict the equilibrium moisture content of pequi diaspore. It was observed that the higher the temperature for the same equilibrium moisture content (% d.b.), the higher the water activity values. As temperature values increased, there was a reduction in the vaporization latent heat of the product. Isosteric heat values of diaspores of pequi fruits in the moisture content range of 4.02 to 16.63 (% d.b.) varied from 2,776.49 to 2,558.39 kJ kg-1.

Highlights

Fruits from the Cerrado, such as pequi (Caryocar Brasiliense, CAMB.), are little studied and there is lack of information on the best form of processing and packaging, as the best conditions to promote the safe storage of the product
With the increase in aw at the same temperature, there was an increment in the values of equilibrium moisture content for the temperatures of 10, 20, 30 and 40 oC in the studied range of water activity, from 0.20 to 0.84 (Table 1)
The values of integral isosteric heat of desorption for pequi diaspores in the moisture content range of 4.02 to 16.63 (% d.b.) varied from 2,776.49 to 2,558.39 kJ kg-1

Summary

Introduction

Fruits from the Cerrado, such as pequi (Caryocar Brasiliense, CAMB.), are little studied and there is lack of information on the best form of processing and packaging, as the best conditions to promote the safe storage of the product. The word ‘pequi’ means ‘prickly shell’ (Souza & Salviano, 2002) and the species has been studied because of its economic importance due to culinary use of its fruits, as sources of vitamins E and B, and in the extraction of oil from the seeds for the production of cosmetics (Almeida & Silva, 1994; Silva et al, 2001; Vera et al, 2005). Many authors studied the sorption isotherms of various products, such as crambe fruits (Costa et al, 2015a), Buchenavia capitata seeds (Costa et al, 2015b), lyophilized yellow mombin pulp (Oliveira et al, 2014), guava in powder (Santos et al, 2014), ‘caju-de-árvore do cerrado’ (Anacardium othonianum) (Caetano et al, 2012)

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