The present work aimed to perform the drying kinetics of melon seeds at different drying temperatures and to adjust the diffusion model to the experimental data considering the geometry of an infinite cylinder. The drying was carried out in an air circulation oven at temperatures of 50, 60 and 70 ºC and with an air speed of 1.5 m s-1, based on the data obtained and considering the melon seeds with infinite cylinder geometry. The parameters were calculated by the analytical solution using the diffusion equation. The coefficient of determination showed values above 0.99 and low values of the chi-square function, indicating that the diffusion model presented satisfactory adjustment to the experimental data of the drying kinetics of melon seeds. According to the data obtained in the drying kinetics of melon seeds, it was seen that the effective diffusivity, the heat transfer coefficient and the Biot number showed a strong positive correlation, indicating that the temperature increase was directly proportional to the values of the parameters calculated diffusion rates. The increase in temperature favors mass transfer, decreasing the dynamic equilibrium humidity and drying time, which varied from 1020, 940 and 880 minutes to temperatures of 50, 60 and 70 °C, it appears that for the longest interval greater time variations were the humidity variations inside the seed.
<p>Com o objetivo de<strong> </strong>analisar a distribuição temporal e a tendência da precipitação pluvial para o município de Bom Jesus - PI relacionando o estudo com regressão linear e medidas de tendência central e de dispersão dos índices pluviométricos mensais e anuais, a estação chuvosa dura seis meses (novembro a abril) com valor médio do período de 875,1 mm, correspondendo a 88,86% da precipitação anual. Em 55 anos de precipitação observada sua média histórica é de 984,8 mm. Conforme a análise de regressão linear da série histórica de precipitação do período de 1960 a 2014, a tendência de maior variabilidade da precipitação centra-se entre os meses de novembro a abril, e os menores índices pluviométricos centra-se entre os meses de maio a setembro, que possui baixos índices pluviométricos.</p><p align="center"><strong><em>Diagnosis and trend rainfall in Bom Jesus - Piauí, Brazil</em></strong><strong><em></em></strong></p><p><strong>Abstract</strong><strong>: </strong>With the objective of analyse the temporal distribution and trend of rainfall for the city of Bom Jesus - PI related study with linear regression and measures of central tendency and dispersion of the monthly and annual rainfall, the six-month rainy season (November to April) with an average value of875.1 mm period, corresponding to 88.86% of the annual precipitation. In 55 years of rainfall observed its historical average is984.8 mm. As will analysis Linear regression of the time series period of rainfall 1960-2014, the trend of increased rainfall variability focuses during the months from November to April, and the lowest rainfall is centered between the months of May to September, that It has low rainfall.</p>
The present article aims to apply two conservation techniques (convective drying and lyophilization) to the jabuticaba peels and to characterize the powders obtained regarding the physicochemical parameters and bioactive compounds, thus evaluating their effect on their composition. Convective drying of the shells was performed in an air circulation oven at 50 °C and 1.0 m.s-1 air velocity for 24h, and lyophilization was performed at -50 °C for 48 h. In natura peels and powders obtained were characterized by the following physicochemical parameters: moisture, ash, lipids, protein, crude fiber, carbohydrates, water activity, pH, acidity, reducing sugars, total soluble solids; and bioactive compounds: anthocyanins, flavonoids, total phenolic compounds and antioxidant activity by ABTS. The use of jabuticaba bark in natura and after drying in flour form are viable for the development of new products, as a way to minimize the disposal of residues produced by the agrifood industry. Through the results obtained the jabuticaba bark flour was considered to be a source of phenolic compounds with antioxidant activity and fiber and could be considered a functional food. Comparing the drying techniques used, the lyophilization stood out because it presented a better preservation of the physicochemical parameters and the bioactive compounds.
The aim of the present study was to evaluate the impact of pulsed electric field (PEF) on the structural, morphological, functional, textural and rheological properties of red rice starch (Oryza sativa). The 5 mm thick starch pastes were subjected to PEF at 10 and 30 kV cm−1 with a pulse frequency of 600 Hz for 90 s. PEF was responsible for decreasing crystallinity, due to the damage caused during processing. The spectra showed different intensities in the bands close to 1000 cm−1, a characteristic region of starch. PEF30 showed greater stability and less retrogradation. The values for textural and rheological parameters were decreased, showing the effect of treatments on amylopectin chains. Therefore, based on the results, nonthermal modification of red rice starch by PEF at 30 kV cm−1 is the most suitable formulation to obtain a new material with optimized characteristics. Practical Applications The results of this study are beneficial for the industry, where its use to process rice starch‐based foods is targeted. Due to the practicality and efficiency when it comes to a nonthermal process, the modification of the structures and the improvement of the nature of food materials is the main objective. The advantage of PEF is that it can be applied to solid foods (in the form of a paste) and to liquids (food fluids), varying system parameters such as electrical intensity. When working with starch in paste form, the article shows that the highest intensity (30 kV cm−1) was the most indicated.
1 Cinética de secagem do feijão azuki: modelagem matemática e propriedades termodinâmicas Azuki bean drying kinetics: mathematical modeling and thermodynamic properties Cinética de secado de frijol azuki: modelado matemático y propiedades termodinâmicas Resumo O presente trabalho tem por objetivo realizar a cinética de secagem do feijão azuki, em diferentes temperaturas de ar de secagem, ajustar modelos matemáticos aos dados experimentais e determinar as suas propriedades termodinâmicas. A cinética de secagem foi realizada nas temperaturas de 40, 50, 60, 70 e 80 °C na velocidade de ar de 1,5 m/s. Os modelos matemáticos de Parry, Page e Handerson e Pabis foram ajustados aos dados experimentais; Foram calculadas a difusividade efetiva, energia de ativação e as propriedades termodinâmicas: entalpia, entropia e energia livre de Gibbs. O modelo de Page foi o que melhor se ajustou aos dados experimentais da cinética de secagem do feijão azuki, pois apresentou elevados valores para o coeficiente de determinação e os menores valores para o desvio quadrático médio; a difusividade aumentou com aumento da temperatura de secagem e o processo apresentou uma energia de ativação de 27,69 kJ/mol; a partir das propriedades termodinâmicas foi possível concluir que, as mesmas foram afetadas pelo aumento da temperatura de secagem, com reduções de entalpia e entropia e aumento da energia livre de Gibbs indicando um processo endergônico não espontâneo. Palavras-chave: Conservação; Energia de ativação; Entalpia; Page. AbstractThe present work aims to perform the drying kinetics of adzuki beans under different drying air temperatures, to adjust mathematical models to experimental data and to determine their Research, Society and Development, v. 9, n. 3, e27932316, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i3.2316 Assim, a energia de ativação (Ea) encontrada para a secagem do feijão azuki é de 27,69 kJ.mol -1 . No qual, encontra-se dentro da faixa apresentada por Zogzas et al. (1996), onde afirma que que varia para produtos agrícolas entre 12,7-110 kJ.mol -1 . Silva et al. (2008), obtiveram energia de ativação de 26,90 kJ.mol -1 ao realizarem a secagem do feijão macassar variedade sempre verde. Na Tabela 4, pode-se observar os valores obtidos para as propriedades termodinâmicas da cinética de secagem do feijão azuki.
O presente estudo teve como objetivo extrair amido de sementes de feijão preto e ajustar modelos matemáticos empíricos aos dados obtidos experimentalmente na sua cinética de secagem. A extração do amido das sementes de feijão preto foi realizada fazendo-se o uso de uma solução de metabissulfito de sódio (0,5 %). A pasta obtida após o processo de extração foi submetida a uma cinética de secagem nas temperaturas de 40, 50 e 60 °C e velocidade do ar de 1,5 m s-1. Aos dados experimentais foram ajustados modelos matemáticos empíricos, no qual foram avaliados através dos indicadores estatísticos coeficiente de determinação (R2) e função qui-quadrado (X2) e por fim o rendimento de extração foi calculado como porcentagem de massa do amido obtido em relação à massa bruta das sementes de feijão preto. O coeficiente de determinação (R2) de todos os modelos aplicados apresentaram valores superiores a 0,98 (R2 >0,98) e o modelo de Page apresentou os menores valores para função qui-quadrado, no qual variam de 0,005637 a 0,003212. Os valores de rendimento de extração variaram de 45,35 a 47,62% sendo o maior percentual obtido na temperatura de 60 °C. No entanto, o modelo de Page na temperatura de 50 °C é o mais adequando para representar esse estudo, pois apresentou o maior valor de R2 (0,9998) e o menor valor da função qui-quadrado (0,3212x10-2).
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