Isotermas de adsorção e calor isostérico da palma forrageira enriquecida proteicamente

Campos, Ana Regina Nascimento; Silva, Flávio L. H. da; Gomes, Josivanda Palmeira; Oliveira, Líbia S. C.; Oliveira, Marinévea Medeiros de

doi:10.1590/s1415-43662009000600011

Cited by 9 publications

(7 citation statements)

References 10 publications

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“…These values are shown in Table 2. Figure 2 shows that the reduction in the moisture content increases the energy required to remove water from the product, represented by the values of integral isosteric heat of desorption (Q st ), as observed for different vegetables such as quinoa (TOLABA et al, 2004), food groups (KUMAR et al, 2005), beans (RESENDE et al, 2006), sweet potato (FASINA, 2006), nutritionally enriched cactus (CAMPOS et al, 2009), the leaves and stems of dehydrated cilantro (SILVA et al, 2010), sweet corn (OLIVEIRA et al, 2010), cassava flour (AYALA-APONTE, 2011) and dehydrated passion fruit pulp (CATELAM et al, 2011). Brooker et al (1992 claimed that the amount of energy required to remove water from seeds with low moisture content is greater than that required for moist products.…”

Section: Resultsmentioning

confidence: 84%

<b>Thermodynamic properties of water desorption of forage turnip seeds

et al. 2014

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ABSTRACT. The purpose of this study was to determine the thermodynamic properties of the process of water sorption in forage turnip seeds. The equilibrium moisture content of forage turnip seeds was determined by the gravimetric-dynamic method for different values of temperature and water activity. According to the results, increasing the moisture content increases the energy required for the evaporation of water in forage turnip seeds, and the values of integral isosteric heat of desorption, within the moisture content range of 3.33 to 11.30 (% d.b.), varies from 4,222.70 to 2,870.34 kJ kg -1. With the elevation in the equilibrium moisture content, there is an increase in differential entropy and Gibbs free energy, which has positive values, demonstrating non-spontaneity in the process of desorption in the seeds. The theory of enthalpy-entropy compensation can be satisfactorily applied to the sorption phenomenon, and the process of water desorption of forage turnip seeds is controlled by enthalpy.

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Section: Resultsmentioning

confidence: 84%

<b>Thermodynamic properties of water desorption of forage turnip seeds

et al. 2014

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“…Figure b–d presents the plots of net isosteric heat, differential entropy and Gibbs energy, respectively, as a function of equilibrium water content. Isosteric heat is a thermodynamic property of water sorption crucial to the analysis of the heat and mass transfer phenomenon (Campos, da Silva, Gomes, Oliveira, & Oliveira, ). Through total isosteric heat, the minimum amount of heat required to remove an amount of water can be estimated, and some deductions are made on the microstructure and physical changes occurring on the food surface.…”

Section: Resultsmentioning

confidence: 99%

Construction of a design space for goat milk powder production using moisture sorption isotherms

Nascimento

Cavalcanti‐Mata

Duarte

et al. 2019

J Food Process Engineering

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Industrialization of goat milk is critical to meet increasing demand. For process optimization and proper preservation of the product, information given by sorption isotherms can be fundamental. Therefore, the objective of this work was to determine the sorption isotherms of the goat milk powder and use that information to build a design space for the spray drying process. By fitting different mathematical models (GAB, Cavalcanti Mata, Thompson, and Oswin) to the experimental data, thermodynamic data was also determined as a function of equilibrium water content. The results allowed the construction of a phase diagram based on glass transition temperatures, and moisture content of 2.40% at the monolayer which provided a reference for the range of stability of water activity and a target for the final moisture content. By determination of net isosteric heat, it is clear that the values of energy for drying goat milk beyond the monolayer moisture content is much higher than for pure water vaporization enthalpy. Finally, using the fitted GAB model it was possible to construct a design space for the spray drying process of goat milk, and optimal spray drying parameters were determined. Practical Applications The construction of a production design space is critical for process scale‐up. On our work, we developed a new method to build such design space using the information provided by the moisture sorption isotherm and a fundamental model for the spray drying process. Therefore, a theoretical design space can be built with minimal resources which can be very useful for new products.

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“…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: Methodsmentioning

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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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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Isotermas de adsorção e calor isostérico da palma forrageira enriquecida proteicamente

Cited by 9 publications

References 10 publications

<b>Thermodynamic properties of water desorption of forage turnip seeds

<b>Thermodynamic properties of water desorption of forage turnip seeds

Construction of a design space for goat milk powder production using moisture sorption isotherms

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

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