Moisture desorption isotherms of cucumber seeds: modeling and thermodynamic properties

Corrêa, Paulo César; Reis, Maycon Fagundes Teixeira; Oliveira, Gabriel Henrique Horta de; Oliveira, Ana Paula Lelis Rodrigues de; Botelho, Fernando Mendes

doi:10.1590/2317-1545v37n3149549

Cited by 24 publications

(32 citation statements)

References 24 publications

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“…These results corroborate those obtained by Corrêa et al (2015), who observed increase in the equilibrium moisture content of coffee (Coffea canephora) fruits as a function of water activity for a specific temperature, and its reduction with the increase of temperature for a certain water activity, in both desorption and adsorption. The reduction in the equilibrium moisture content with the increase in temperature can be justified based on the increase of the water vapor pressure in the air and on the surface of the product (Campos et al, 2009).…”

Section: Methodssupporting

confidence: 92%

“…Important post-harvest steps include fruit drying and storage and, to correctly perform these operations, it is essential to know the relationships existing between the product and the surrounding air (Corrêa et al, 2015). The conservation of quality of the products depends on the environmental conditions of relative humidity and temperature under which they will be stored (Borges et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Hygroscopicity of ‘sucupira-branca’ (Pterodon emarginatus Vogel) fruits

Oliveira

Resende

Costa

et al. 2017

Rev. bras. eng. agríc. ambient.

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A B S T R A C T'Sucupira-branca' (Pterodon emarginatus Vogel) is a tree from 'Cerrado' and stands out mainly for its pharmacological properties; however, there are no technological information about its post-harvest operations. Thus, the aim of this study was to determine the sorption isotherms of 'sucupira-branca' fruits for different air conditions and obtain the values of desorption isosteric heat, depending on the equilibrium moisture content of the product. The equilibrium moisture content of 'sucupira-branca' fruits was determined by dynamic method for temperatures of 25, 30, 35 and 40 °C and water activities for each temperature between 0.270 and 0.775. The models Chung-Pfost, Copace, Modified Halsey, Oswin Modified and Sigma Copace obtained high coefficient of determination (R 2 ) and low chisquare (χ 2 ), relative mean error (P) and estimated mean error (SE), and the Copace model was selected to represent the desorption isotherms. The isosteric heat increases with the reduction of equilibrium moisture content and required more energy to remove water from the 'sucupira-branca' fruit.Higroscopicidade dos frutos de sucupira-branca (Pterodon emarginatus Vogel) R E S U M OA sucupira-branca (Pterodon emarginatus Vogel) é uma árvore do Cerrado e se destaca principalmente por suas propriedades farmacológicas; entretanto, inexistem informações tecnológicas sobre as operações de pós-colheita. Desta forma, objetivou-se, com este trabalho, determinar as isotermas de dessorção dos frutos de sucupira-branca para diferentes condições do ar, bem como obter os valores do calor isostérico de dessorção em função do teor de água de equilíbrio do produto. O teor de água de equilíbrio dos frutos de sucupira-branca foi determinado pelo método dinâmico para temperaturas de 25, 30, 35 e 40 °C e atividades de água para cada temperatura, entre 0,270 a 0,775. Os modelos Chung-Pfost, Copace, Halsey Modificado, Oswin Modificado e Sigma Copace obtiveram elevado coeficiente de determinação (R 2 ) e baixo Qui-quadrado (χ 2 ), erro médio relativo (P) e estimado (SE), sendo o modelo de Copace selecionado para representar as isotermas de dessorção. O calor isostérico aumenta com a redução do teor de água de equilíbrio, sendo relevante maior quantidade de energia para retirar a água dos frutos de sucupira-branca.

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Section: Methodssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Hygroscopicity of ‘sucupira-branca’ (Pterodon emarginatus Vogel) fruits

Oliveira

Resende

Costa

et al. 2017

Rev. bras. eng. agríc. ambient.

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“…Gibbs free energy increases with decreasing moisture content, being positive for all temperatures studied, with a tendency to stabilize at higher levels of equilibrium moisture content. This behavior was also observed by Corrêa et al (2015) and by Sousa et al (2015) when studying cucumber and fodder radish seeds, respectively. Gibbs free energy is related to the work required to make sorption sites available (Nkolo Meze'e et al, 2008).…”

Section: Table 2 Ratio Between L/l' For the Different Moisture Contesupporting

confidence: 66%

THERMODYNAMIC PROPERTIES OF BARU FRUITS (Dipteryx alata Vogel)

et al. 2017

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ABSTRACT:The objective of this study was to determine and evaluate the thermodynamic properties for different equilibrium moisture contents in baru fruits (Dipteryx alata Vogel), using the direct static method to obtain the experimental data. The Modified Halsey model was used to determine the thermodynamic properties of baru fruits. Results concluded that thermodynamic properties are influenced by moisture content. The water vaporization latent heat increases with the decrease in equilibrium moisture content. The baru fruit desorption process is controlled by enthalpy. Gibbs free energy is positive for the temperatures studied with the increase over desorption, which describes a non-spontaneous process.

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“…These parameters thermodynamic parameters of different seeds, similar in shape and size to lettuce seeds, such as grape seed (Vitis sp) (MAJD et al, 2014), turnip seed (Brassica rapa subsp. rapa) (SOUSA et al, 2015), cucumber seed (Cucumis sativus L.) (CORRÊA et al, 2015) and pepper seed (Capsicum sp) (SILVA et al, 2016). Therefore, even though there is a considerable wealth of literature about thermodynamic properties, information in the thermodynamic properties of lettuce seeds is still emerging.…”

Section: Methodsmentioning

confidence: 99%

Thermodynamic properties of water desorption in lettuce seeds

Zeymer

Corrêa

Oliveira

et al. 2018

SCA

Self Cite

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Knowledge of the movement of water molecules inside material is important for the study of interactions between water and chemical components of agricultural products. The thermodynamic properties calculation reports this need, being the source of information to design drying equipment, calculate the energy required in this process and evaluate the physical phenomena that occur on the food surface. Given the importance of the subject, the objective of this study was to determine the thermodynamic properties of the water desorption process in lettuce seeds. Lettuce seeds had an initial moisture content of 9.3% (d.b.). The equilibrium moisture content of seeds was determined by static gravimetric method at different temperatures (10, 20, 30, 40 and 50 ± 1 °C) and relative humidity values (between 11 and 96%). Experiments were conducted in triplicate. It was observed that, with increasing equilibrium moisture content, there was a reduction in the energy required for evaporation of water in lettuce seeds, with values of integral isosteric heat of desorption in the water content range 2.1 to 21.2% (d.b.) which varied from '4164.89 to 2477.43' kJ kg -1 . With increasing equilibrium moisture content there was a decrease in differential entropy, resulting in lower demand for mobility of water molecules. The Gibbs free energy also decreased with increasing equilibrium moisture content and was positive for all temperatures studied, showing non-spontaneity of water desorption in the seeds. The enthalpy-entropy compensation theory was has been satisfactorily applied to the sorption phenomenon and the water desorption process in lettuce seeds was controlled by enthalpy. Key words: Differential enthalpy. Differential entropy. Enthalpy-entropy compensation theory. Equilibrium moisture content. Gibbs free energy. Isosteric heat. ResumoO conhecimento da movimentação das moléculas de água dentro do material é importante para o correto estudo das interações entre a água e os componentes químicos dos produtos agrícolas. O cálculo das propriedades termodinâmicas relata essa necessidade, sendo fonte de informação para projetar equipamentos de secagem, calcular a energia requerida nesse processo e avaliar os fenômenos físicos que ocorrem na superfície dos alimentos. Diante da importância do assunto, o objetivo do presente trabalho foi determinar as propriedades termodinâmicas do processo de dessorção de água em sementes de alface. As sementes de alface possuíam teor de água inicial de 9,3% (b.s. equilíbrio das sementes foi determinado pelo método estático-gravimétrico para diferentes valores de temperatura (10, 20, 30, 40 e 50 ± 1 °C) e atividade de água (entre 11 e 96%), em três repetições. De acordo com os resultados encontrados, observou-se que com o aumento do teor de água de equilíbrio, ocorre redução da energia necessária para a evaporação da água nas sementes de alface, sendo que os valores do calor isostérico integral de dessorção, na faixa de teor de água de 2,1 a 21,2% (b.s.), variaram de 4164,89 a 2477,43 kJ kg -1 ...

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Moisture desorption isotherms of cucumber seeds: modeling and thermodynamic properties

Cited by 24 publications

References 24 publications

Hygroscopicity of ‘sucupira-branca’ (Pterodon emarginatus Vogel) fruits

Hygroscopicity of ‘sucupira-branca’ (Pterodon emarginatus Vogel) fruits

THERMODYNAMIC PROPERTIES OF BARU FRUITS (Dipteryx alata Vogel)

Thermodynamic properties of water desorption in lettuce seeds

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