Resumo: A batata yacon tornou-se popular devido aos inúmeros benefícios que proporciona à saúde, porém seu tempo de vida útil é curto, aliado ao escurecimento enzimático, comum em alimentos ricos em compostos fenólicos, que reduz e restringe o seu consumo. Em virtude de ser um produto de alto valor, e com o intuito de se evitar o seu desperdício, justifica-se o estudo de meios de conservação do mesmo. A secagem seguida por transformação do produto em pó se apresenta como uma alternativa conveniente, segura e capaz de proporcionar longa vida útil ao material processado. Diante do exposto, objetivou-se verificar o comportamento higroscópico do pó obtido pela liofilização do mix de batata yacon e suco de lima ácida Tahiti nas temperaturas de 20, 30 e 40 ºC. Elaborou-se um mix de batata yacon com suco de lima ácida Tahiti, aproveitando a propriedade deste suco de atuar na inativação enzimática da enzima polifenoloxidase, além de ser fonte de vitamina C. O mix com maltodextrina foi seco por liofilização e o pó resultante foi submetido à análise de comportamento higroscópico, determinando-se as isotermas de adsorção de umidade nas temperaturas de 20, 30 e 40 ºC e ajustando-se os modelos matemáticos de Peleg, GAB, Halsey, Oswin e Smith às isotermas. O modelo de Peleg foi o que melhor se ajustou às isotermas de adsorção de umidade do pó da batata yacon com suco de lima ácida Tahiti. As isotermas foram classificadas como Tipo II e a umidade na monocamada molecular apresentou valor em torno de 7% b.s. Palavras-chave: Atividade de água; Isotermas de adsorção; Smallanthus sonchifoliaAbstract: The yacon potato became popular because of the numerous benefits it provides to health, but their life span is short, combined with enzymatic browning, common in foods rich in phenolic compounds, which reduces and limits its consumption. By virtue of being a product of high value and in order to avoid wastage, justified the study of conservation means where drying followed by processing of the product powder is presented as a convenient alternative, safe and able to provide long useful life to processed material. Given the above, it elaborated a yacon potato mix with lemon juice, taking ownership of this juice to act in the enzymatic inactivation of PPO, besides being a source of vitamin C. The mix with maltodextrin was then dried by lyophilisation and resulting powder was subjected to the hygroscopic behavior analysis, determining the moisture adsorption isotherms at temperatures of 20, 30 and 40 °C, and adjusting the mathematical models Peleg, GAB, Halsey, Oswin and Smith isotherms. The Peleg model was the best fit the moisture adsorption isotherms of powder yacon potato with lemon juice; isotherms were classified as Type II and moisture in the molecular monolayer presented value around 7% b.s.
A abóbora (Cucurbita moschata) é uma hortaliça apreciada por pessoas de todos os níveis de renda, porém, suas sementes são descartadas, caracterizando um desperdício em virtude da sua rica composição nutricional. Uma das formas de minimizar esse descarte é disponibilizar alternativas de uso da semente, aumentando seu atrativo para industrialização e consequentemente as possibilidades da sua aplicação na elaboração de alimentos para o consumo humano. Desse modo, objetivou-se avaliar as características físicas, fisico-quimicas e colorimétricas das sementes de abóbora in natura, germinadas e da farinha da semente de abóbora germinada. As amostras foram caracterizadas quanto a massa específica unitária, real e aparente, porosidade, cor, volume, comprimento, largura, espessura, circularidade, esfericidade, teor de água, atividade de água, pH, acidez total titulável, cinzas, lipídios, proteínas, açucares totais e redutores, determinou-se ainda as isotermas de adsorção de umidade das farinhas secas em temperaturas de 20, 25 e 30º C. Verificou-se que o modelo de Peleg, seguido do modelo de Oswin, foram os que apresentaram os melhores ajustes aos dados experimentais. A germinação alterou a massa unitária, porosidade, os parâmetros colorimétricos e gerou um aumento considerável no teor de proteínas. A secagem provocou transformações na massa unitária, porosidade, circularidade e esfericidade. Quanto aos parâmetros físico-químicos, houve redução do pH e açucares redutores e aumento dos teores de lipídios e proteínas. Sendo assim, a farinha de semente de abóbora germinada apresentou bons resultados, principalmente em relação ao teor de proteínas, apresentando-se como uma boa alternativa para o desenvolvimento de novos produtos.
PurposeTo describe water absorption by the rice grains over time, diffusion and empirical models were used. Also, an optimization software was developed in this study to determine parameters and their uncertainties for the diffusion models (LS Optimizer, for partial differential equations). Parameters (and their uncertainties) for empirical models were determined by LAB Fit Curve Fitting Software.Design/methodology/approachHeat and mass diffusion phenomena are found in various processes of technological interest, including pasteurization, drying and water immersion of agricultural products, among others. The objective of this work was to study the process of water absorption by rice grains with and without husk, using diffusion and empirical models to describe the absorption kinetics. Rice grains were immersed (approximately 10 g for each experiment) in drinking water maintained at constant temperatures of 28, 40 and 50 C. In the experiments, the water contents absorbed by rice grains over time were obtained by the gravimetric method.FindingsAmong empirical models, Peleg was the most satisfactory to describe the kinetics of water absorption by rice without husk, while the Silva et alii model had the best statistical indicators for rice with husk. It was also verified that a diffusion model with boundary condition of the first kind showed the best (or equivalent) results in the description of all processes of kinetics of water absorption by rice grains, with and without husk. For grains without husk, the effective mass diffusivities were (1.186 ± 0.045) × 10−9, (1.312 ± 0.024) × 10−9 and (2.133 ± 0.028) × 10−9 m2 min−1, for the immersion temperatures of 28, 40 and 50C, respectively. For grains with husk, diffusivities were (0.675 ± 0.011) × 10−9 and (1.269 ± 0.017) × 10−9 m2 min−1, for temperatures of 28 and 50 C, respectively.Originality/valueThis work developed a solver for the diffusion equation in cylindrical geometry and presented the LS Optimizer software developed to determine differential equation parameters through experimental data sets.
The objective of this work was to intermittently and continuously dry “Neve” melon seeds and study their behavior. The seeds were dried in a fixed-bed dryer at a temperature of 60 °C under the influence of air velocity of 1 m s−1, followed by the prediction of drying kinetics, including that of intermittent processes with its effective time (pseudo-continuous drying) and tempering time (intermittent drying). The dried seeds were crushed to produce flour. The flours were evaluated for physicochemical parameters. To describe drying kinetics (continuous and intermittent drying) of “Neve” melon seeds, empirical models were used, including a new model proposed in this article to describe intermittent drying when the period of intermittence is included in the process. An optimization software was developed (LS Optimizer) and used to determine parameters (and their uncertainties) of the intermittent drying. The parameters of empirical models, used to describe continuous and pseudo-continuous drying, were determined by LAB Fit Curve Fitting Software. The Page model was the one that best fitted in the prediction of the experimental data of continuous and pseudo-continuous drying kinetics of seeds. A new model proposed in this work, based on Page and Lewis equations, was able to predict the kinetics of intermittent drying processes including the tempering time. The flours showed moisture content below 6%, and intermittent drying preserved proteins and lipids more than continuous drying, especially with drying and tempering periods of 10 and 20 min, respectively.
Myrtle is a fruit with great industrial potential, due to its nutritional characteristics and presence of phenolic compounds, especially anthocyanins. Nonetheless, the high perishability and short post-harvest life of this fruit limit its diffusion in the internal market and use in the food processing industry. Lyophilization of fruit pulps represents an alternative to increasing preservation time, resulting in a powder with higher stability and longer shelf life. In this context, this study was aimed to evaluate the stability of myrtle pulp powder during storage in laminated packages and under controlled conditions of temperature (between 30 and 40 ºC), and evaluate the kinetics of degradation of anthocyanins and flavonoids. As storage time increased at both temperatures, moisture content and water activity increased; and caused reductions of anthocyanins, flavonoids and lightness. In the evaluation of the kinetics of degradation of anthocyanins and flavonoids, the zero-order was the best model to represent the behavior and with higher stability at a temperature of 20 ºC.
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