Drying kinetics and physical and chemical characterization of white-fleshed ‘pitaya’ peels

ABSTRACT The objective of this work was to obtain the drying kinetic curves of white-fleshed ‘pitaya’ peels and characterize the obtained powder regarding physical and chemical parameters. Different mathematical models were fitted to the experimental data of drying kinetics, considering the coefficient of determination (R2), mean square deviation (MSD) and residual distribution as fit criteria. The peels had an initial moisture content of 93.38% (w.b.) and final moisture contents of 5.39% at temperature of 50 °C, 5.27% at 60 °C and 4.40% at 70 °C. After drying, the peels were disintegrated to obtain the powders and characterized for moisture content, reducing sugars, total titratable acidity, ascorbic acid, betacyanins, betaxanthins, water activity and color, in order to evaluate the influence of temperature on the quality of powders. The Page model was the one that best fitted to the experimental data, presenting coefficient of determination higher than 0.998, mean square deviation lower than 0.02 and random distribution of residuals. Increment in drying air temperature promoted increase of pH, ascorbic acid, luminosity and yellowness, and reduction of moisture content, reducing sugars, acidity, betacyanins, betaxanthins, water activity and redness. Considering the retention of betalains, the drying temperature of 50 °C is the most suitable for the production and use of ‘pitaya’ peel powder

Estabilidade de geleias convencionais de umbu-cajá durante o armazenamento em condições ambientais

Neste trabalho propôs-se estudar a estabilidade física e química de geleias convencionais de umbu-cajá durante o armazenamento por 180 dias em condições ambientais. As geleias foram formuladas por meio de planejamento experimental fatorial 22 com 2 experimentos no ponto central resultando em 6 experimentos, variando-se as concentrações de açúcar cristal (50, 55 e 60%) e pectina de alto teor de metoxilação (0,5; 1,0 e 1,5%). As formulações foram aquecidas e concentradas em tacho aberto até atingir teor de sólidos solúveis totais de ≈65 ºBrix, envasadas em recipientes de vidro transparente e estocadas em temperatura e umidade relativa médias de 23,25 ºC e 81%, respectivamente, com análises físicas e químicas a cada 30 dias de armazenamento. De acordo com os resultados o armazenamento das geleias promoveu aumento nos valores de pH, sólidos solúveis totais (ºBrix), ratio (relação sólidos solúveis totais/acidez total titulável), firmeza e adesividade e reduções nos dados de atividade de água, acidez total titulável, luminosidade (L*), intensidade de amarelo (+b*), ângulo de tonalidade (h*) e croma (c*). Observou-se tendência à estabilidade dos valores de teor de umidade e sólidos totais na maioria dos experimentos enquanto, por outro lado, a intensidade de vermelho (+a*) apresentou tendência de elevação na maioria das geleias

Drying kinetics and physical and chemical characterization of white-fleshed ‘pitaya’ peels

<div><p>ABSTRACT The objective of this work was to obtain the drying kinetic curves of white-fleshed ‘pitaya’ peels and characterize the obtained powder regarding physical and chemical parameters. Different mathematical models were fitted to the experimental data of drying kinetics, considering the coefficient of determination (R2), mean square deviation (MSD) and residual distribution as fit criteria. The peels had an initial moisture content of 93.38% (w.b.) and final moisture contents of 5.39% at temperature of 50 °C, 5.27% at 60 °C and 4.40% at 70 °C. After drying, the peels were disintegrated to obtain the powders and characterized for moisture content, reducing sugars, total titratable acidity, ascorbic acid, betacyanins, betaxanthins, water activity and color, in order to evaluate the influence of temperature on the quality of powders. The Page model was the one that best fitted to the experimental data, presenting coefficient of determination higher than 0.998, mean square deviation lower than 0.02 and random distribution of residuals. Increment in drying air temperature promoted increase of pH, ascorbic acid, luminosity and yellowness, and reduction of moisture content, reducing sugars, acidity, betacyanins, betaxanthins, water activity and redness. Considering the retention of betalains, the drying temperature of 50 °C is the most suitable for the production and use of ‘pitaya’ peel powder.</p></div

Cinética de secagem de farinha de grãos residuais de urucum Drying kinetics of residual grain flour of annato

O processo de extração do corante bixina produz enorme quantidade de grãos residuais de urucum que vem sendo descartada em grande parte pelas indústrias. Objetivou-se, neste trabalho, desidratar farinhas de grãos residuais de urucum, com e sem a camada de óleo proveniente do processo de extração dos pigmentos em estufa com circulação forçada de ar nas temperaturas de 40, 50, 60 e 70 ºC e ajustar os modelos matemáticos de Aproximação da Difusão, Dois Termos, Midilli, Page e Thompson aos dados experimentais. As farinhas de grãos residuais de urucum com teor de água inicial de aproximadamente 20% b.u. foram desidratadas até teor de água final de aproximadamente 5% b.u. Como critério de avaliação do ajuste dos modelos matemáticos utilizaram-se o coeficiente de determinação e o desvio quadrático médio. Verificou-se que as amostras de farinha com óleo demandaram maior intervalo de tempo para atingir o teor de água de 5% b.u., em comparação com as amostras de farinha sem óleo. Todos os modelos estudados representaram satisfatoriamente a cinética de secagem das farinhas com e sem óleo, com coeficientes de determinação superiores a 0,95 e valores de desvios quadráticos médios inferiores a 1,0.The process of extracting the bixin colorant produces a large amount of residual annatto seeds that, in most cases, has been discarded by the industries. The objective of this study was to dehydrate residual grain flour of annato, with and without the oil layer originated of the extraction process of the pigments in an oven with forced air circulation at 40, 50, 60 and 70 ºC temperature and to adjust the mathematical models of the Diffusion Approximation, Two Terms, Midilli, Page and Thompson to the experimental data. Residual grain flour of annato with water content approximately 20% w.b. was dried to the final water content of about 5% w.b. As a criterion for evaluating the adjustment of mathematical models the coefficient of determination and mean-square deviation were used. It was found that samples of flour with oil demanded longer time to achieve moisture content of 5% w.b. in comparison to samples of flour without oil. All studied models accounted satisfactorily drying kinetics of flour with and without oil, with determination coefficients above 0.95 and values of mean-square deviation below 1.0

Estabilidade física e química de licores de graviola durante o armazenamento em condições ambientais

Objetivou-se, neste trabalho, desenvolver e avaliar a estabilidade de licores de graviola acondicionados em embalagens de polietileno durante o armazenamento por 240 dias em condi&#231;&#245;es ambientais. Foram elaboradas 5 formula&#231;&#245;es de licores variando-se as concentra&#231;&#245;es de polpa (300, 400 e 500 g) e xarope de sacarose (50, 60 e 70 &#176;Brix). As polpas foram maceradas em &#225;lcool comercial por 20 dias; em seguida, as misturas foram filtradas, adicionadas de xarope e submetidas a um envelhecimento acelerado em banho-maria, a 60 &#176;C, pelo per&#237;odo de 2 h. Os licores foram acondicionados em embalagens de polietileno de baixa densidade e armazenados em temperatura e umidade relativa m&#233;dias de 26 &#176;C e 78%, respectivamente. No tempo inicial e a cada 60 dias de estocagem, por 240 dias, os licores foram submetidos &#224;s an&#225;lises de teor alco&#243;lico, a&#231;&#250;cares totais, s&#243;lidos sol&#250;veis totais (SST), acidez total titul&#225;vel (ATT), raz&#227;o SST/ATT, pH, atividade de &#225;gua e cor (L*, a* e b*). Observou-se que o armazenamento promoveu aumentos significativos (p < 0,05) nos valores de a&#231;&#250;cares totais, SST e cromaticidades a* e b*. Os par&#226;metros de teor alco&#243;lico, atividade de &#225;gua, pH e luminosidade (L*) foram reduzidos enquanto que a ATT e a raz&#227;o SST/ATT permaneceram est&#225;veis ao final da estocagem

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

ABSTRACT Red 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. The results of the physical and chemical analyses showed intermediate wetting time of 0.39 g min-1, 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%