Sorption isotherms in materials of biological origin mathematical and physical approach

Blahovec, J.

doi:10.1016/j.jfoodeng.2004.02.012

Cited by 128 publications

(103 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The mean MA%E for the four temperatures was less than 5.7%. The constants of the GAB model (Xm, C and K) varied with temperature, confirming behaviour found by other authors (Blahovec, 2004;Moreira et al, 2008). According to Blahovec (2004), the constant C decreases and K increases with increasing temperature.…”

Section: Water Sorption Isothermssupporting

confidence: 89%

“…In the GAB model the constants Xm, C and K are dependent on the temperature; Xm represents the moisture of the molecular monolayer on the inner surface (Blahovec, 2004), C is the constant related to the heat of sorption of the monolayer and K is the heat of sorption of the multilayer compared to pure water (Moreira et al, 2008). In Table 1 (Eqs.…”

Section: Modeling Of Sorption Isothermsmentioning

confidence: 99%

See 1 more Smart Citation

Isotherms and isosteric heat of sorption of two varieties of Peruvian quinoa

Ramos¹,

Vieira²,

Telis‐Romero³

et al. 2016

Sc.Agropec

View full text Add to dashboard Cite

The isosteric heats of sorption of two varieties of quinoa (Chenopodium quinoa Willd.) grain were determined by the static gravimetric method at four temperatures (40, 50, 60 and 70 °C) and in relative humidity environments provided by six saturated salt solutions. Six mathematical equations were used to model the experimental data: GAB, Oswin, Henderson, Peleg, Smith and Halsey. The isosteric heat of sorption was determined using the parameters of the GAB model. All the equations were shown to be appropriate by the coefficients of determination (R 2 ) and the mean absolute error (MA%E). The influence of temperature was observed because the adsorption of water by the grains was lower at higher temperatures. The equilibrium moisture contents for security of storage, for long periods of time at water activity lower than 0.65, were 12 -13%. The effect of temperature on the parameters of the GAB model was analysed using the exponential Arrhenius equation. The isosteric heats of sorption were determined by applying the Clausius-Clapeyron equation as a function of humidity. The isosteric heat at 5% moisture for grains of the Blanca de Juli variety was 3663 kJ/kg and for the Pasankalla variety it was 3393 kJ/kg. The experimental data for isosteric heat as a function of humidity were satisfactorily modelled using three mathematical equations.

show abstract

Section: Water Sorption Isothermssupporting

confidence: 89%

Section: Modeling Of Sorption Isothermsmentioning

confidence: 99%

Isotherms and isosteric heat of sorption of two varieties of Peruvian quinoa

Ramos¹,

Vieira²,

Telis‐Romero³

et al. 2016

Sc.Agropec

View full text Add to dashboard Cite

show abstract

“…According to Alcântara et al (2009), for a good representation of the adsorption isotherms of a food, the values of the parameter 'a' in the Oswin model must be higher than zero and those of 'b' must be between zero and 1.0; this model satisfactorily fitted to the experimental data. According to Blahovec (2004), when these parameters are within these intervals, it is an indication that there is no point of inflection in the curve and, consequently, there are no changes in the concavity of the functions; thus, the estimated parameters have mathematical and physical consistency.…”

Section: Resultsmentioning

confidence: 99%

Adsorption isotherms of the red mombin powder produced in spouted bed dryer

Lins

Rocha

Gomes

et al. 2017

Rev. bras. eng. agríc. ambient.

View full text Add to dashboard Cite

A B S T R A C TRed mombin is a seasonal fruit and susceptible to degradation reactions due to its high water content. This highlights the need to use processes that prolong its life and make it available all year round, including to markets away from the production sites. Thus, the objective of this study was to produce red mombin pulp powder in spouted bed dryer, evaluate it regarding physical and chemical parameters and assess its hygroscopic behavior at temperatures of 20, 30 and 40 °C, fitting the models of the GAB, Oswin and Peleg to the experimental data , solubility higher than 60% and mean flowability with Hausner ratio and Carr index of 1.26-1.34 and 0.21-0.25, respectively. The powder particles exhibited spherical shape, smooth surface and some irregularities, with tendency to form agglomerates. The isotherms had a type-II sigmoidal behavior, and the Peleg model, at all temperatures, showed the best fits to the experimental data with determination coefficients above 0.99 and mean percentage deviations lower than 2.0%.Isotermas de adsorção do pó de seriguela produzido em secador de leito de jorro R E S U M OA seriguela é um fruto sazonal e susceptível a reações de deterioração devido ao seu elevado teor de água, o que evidencia a necessidade de utilização de processos que prolonguem sua vida útil e a disponibilize durante todo o ano, inclusive a mercados distantes dos locais de produção. Assim, objetivou-se produzir a polpa de seriguela em pó em secador de leito de jorro, analisá-la quanto aos parâmetros físicos e químicos e avaliar seu comportamento higroscópico nas temperaturas de 20, 30 e 40 °C, com ajustes dos modelos de GAB, Oswin e Peleg aos dados experimentais. Os resultados das análises físicas e químicas evidenciaram tempo de molhagem intermediário, de 0,39 g min -1, solubilidade superior a 60% e média fluidez com fator de Hausner e índice de Carr compreendido entre 1,26-1,34 e 0,21-0,25, respectivamente. As partículas de pó se apresentaram com formato esférico, superfície lisa e algumas irregularidades, com tendência de formação de aglomerados. As isotermas tiveram comportamento sigmoidal do tipo II, com o modelo de Peleg detendo, em todas as temperaturas, os melhores ajustes aos dados experimentais com coeficientes de determinação superiores a 0,99 e desvios percentuais médios inferiores a 2,0%.

show abstract

“…Park & Nogueira (1992) definem este tipo de isoterma segundo a classificação de BET, quando sua forma tem aparência da letra J. Blahovec (2004) estudou alguns modelos de isotermas de sorção realizando um estudo matemático sobre os valores aceitáveis para cada parâmetro. Para o modelo de GAB e para as curvas do tipo III este autor afirma que 0 < K  1 e 0  C  2.…”

Section: Methodsunclassified

Isotermas de adsorção e calor isostérico da palma forrageira enriquecida proteicamente

Campos¹,

Silva²,

Gomes³

et al. 2009

Rev. bras. eng. agríc. ambient.

View full text Add to dashboard Cite

RESUMOO enriquecimento protéico da palma forrageira através de fermentação semissólida com a utilização de leveduras visou aumentar o valor nutricional dessa forragem a fim de que possa ser utilizada como suplemento protéico para ração animal, que poderá ser oferecida ainda úmida ou ser secada e armazenada sob condições adequadas. O presente trabalho foi realizado com o objetivo de estudar as isotermas de adsorção da palma forrageira enriquecida proteicamente, nas temperaturas de 30, 35 e 40°C, escolher o modelo matemático que melhor se ajusta aos dados experimentais e determinar o calor isostérico de adsorção, buscando-se parâmetros para o estudo do armazenamento deste material. A partir dos resultados obtidos verificou-se que o modelo de Henderson foi o que melhor se ajustou aos dados experimentais das isotermas de adsorção nas três temperaturas estudadas e que o calor isostérico de adsorção do produto diminui com o aumento da umidade de equilíbrio. Para o armazenamento da palma enriquecida é necessário que a faixa ideal de atividade de água esteja compreendida entre 0,25-0,35, que corresponde a uma umidade (b.s.) menor que 0,03 eliminando, desta forma, qualquer crescimento de micro-organismos. Palavras-chave: atividade de água, fermentação semissólida, levedura, Opuntia ficus-indica MillAdsorption isotherms and heat isosteric of protein enriched cactus pear ABSTRACTThe protein enrichment of cactus pear through solid-state fermentation with the use of yeasts sought to increase the nutritional value of this forage so that it may be used as protein supplement for animal feed which may be offered either wet or dried and stored under appropriate conditions. The present work had its objective to study the adsorption isotherms of the protein enriched cactus pear, at temperatures of 30, 35 and 40°C, to choose the mathematical model that best adjusted to experimental data and to determine the adsorption heat isosteric, looking for parameters for study of storage of this material. Starting from the obtained results, it was verified that the Henderson model was better if it was adjusted to experimental data adsorption isotherms at the three studied temperatures and that adsorption heat isosteric of studied product decreases with the increase of moisture content. For the storage of the enriched cactus pear it is necessary that the ideal range of activity of water should be between 0.25 -0.35, which corresponds to moisture content (d.b.) smaller than 0.03, eliminating, this way, any growth of microorganisms.

show abstract

Sorption isotherms in materials of biological origin mathematical and physical approach

Cited by 128 publications

References 11 publications

Isotherms and isosteric heat of sorption of two varieties of Peruvian quinoa

Isotherms and isosteric heat of sorption of two varieties of Peruvian quinoa

Adsorption isotherms of the red mombin powder produced in spouted bed dryer

Isotermas de adsorção e calor isostérico da palma forrageira enriquecida proteicamente

Contact Info

Product

Resources

About