<b>Thermodymnamic properties of crambe fruits

Abstract

ABSTRACT. This study aimed to determine and evaluate the thermodynamic properties of crambe fruit at different equilibrium moisture contents. The dynamic-gravimetric method was used to collect experimental data. Crambe fruits with an initial moisture content of approximately 26% db (dry basis) were used. The thin-layer desorption of the product was conducted at different controlled temperatures (25, 30, 35, 40, and 45°C) and at water activity levels ranging from 0.10 to 0.89 until the product reached the equilibrium moisture content at the specified air condition. In conclusion, the thermodynamic properties of crambe fruit are affected by temperature and moisture content. The isokinetic theory is valid for the desorption process, which is controlled by enthalpy, and the Gibbs free energy is positive at all of the tested temperatures, which indicates that water desorption is not a spontaneous process. Keywords:Crambe abyssinica, enthalpy, entropy, Gibbs free energy. Propriedades termodinâmicas dos frutos de crambeRESUMO. O objetivo no presente trabalho foi determinar e avaliar as propriedades termodinâmicas para diferentes teores de água de equilíbrio dos frutos de crambe. Para obter os dados experimentais utilizou-se o método dinâmico-gravimétrico. Foram utilizados frutos de crambe, com teor de água inicial de, aproximadamente, 26 % b.s. (base seca). A dessorção do produto em camada delgada foi realizada para diferentes condições controladas de temperatura (25, 30, 35, 40 e 45°C) e atividades de água entre 0,10 e 0,89, até que o produto atingisse seu teor de água de equilíbrio com a condição do ar especificada. Concluise que as propriedades termodinâmicas dos frutos de crambe são influenciadas pelas temperaturas e pelos teores de água. A teoria da isocinética é válida para o processo de dessorção, sendo este controlado pela entalpia. A energia livre de Gibbs é positiva para todas as temperaturas estudadas, indicando que a dessorção da água é um processo não espontâneo. Palavras-chave:Crambe abyssinica, entalpia, entropia, energia livre de Gibbs.

Thermodynamic Properties of White Bean Grains for Different Equilibrium Water Contents

“…This isokinetic temperature was higher than the temperature of the harmonic mean, showing that the process is controlled by enthalpy. These results are in line with the observations of several researchers, who successfully applied the isokinetic theory to the sorption of various agricultural products (Oliveira et al, 2014(Oliveira et al, , 2017Kurozawa et al, 2015;Silva et al, 2015).…”

“…In drying processes and in the storage of agricultural products, knowledge of thermodynamic properties is used in the analysis of sorption behavior in biological systems. Its study is indispensable in the search for solutions to problems related to stability issues and in the optimization of the conditions of industrial processes (Corrêa et al, 2017;Oliveira et al, 2017). Cavalcanti et al (2018), studying thermodynamic properties of white bean seeds, concluded that the isosteric heat of desorption is increased 20 to 21 times when the water content is reduced from 0.30 to 0.05 on a dry basis (d.b.…”

THERMODYNAMIC PROPERTIES OF TAMARIND SEEDS (Tamarindus indica L.)

“…The latent heat of vaporization of water of tamarind seeds decreases with increasing temperature for the same moisture content, presenting an inversely proportional relationship and corroborating with results obtained by Oliveira et al (2017).…”

“…The latent heat of vaporization of water, differential enthalpy, net isosteric heat of desorption, and Gibbs free energy are among the thermodynamic properties of the product. These thermodynamic properties have been extensively studied in the literature due to their importance for different plant products, such as cassava (Koua et al, 2014), Barbados nut (Chaves et al, 2015) seeds, castorbean seeds (Goneli et al, 2016), crambe fruits (Oliveira et al, 2017), and baru (Dipteryx alata Vogel) fruits (Resende et al, 2017).…”

Propriedades termodinâmicas da polpa de cajá (Spondias mombin L.)

“…Research, Society and Development, v. 9, n. 6, e02963396, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i6.3396 O equilíbrio higroscópico de frutos e grãos relata a relação entre o teor de umidade do produto e a umidade relativa em uma temperatura específica. Este parâmetro pode fornecer informações sobre a estabilidade durante o armazenamento e indicar a embalagem adequada para comercialização do produto alimentício (Oliveira et al, 2017).…”