ABSTRACT
ABSTRACT: The influence of drying methods (oven drying at 50 °C, and freeze drying) on the centesimal composition, functional characteristics and rheological properties of mucilage obtained from chia seed and psyllium husk were investigated. Results showed that high temperature of oven drying reduced fiber content, solubility, emulsion activity and emulsion stability of mucilage. All samples showed pseudo plastic behavior, with the best result produced by Heschel-Bulkley and Power Law models of chia and psyllium mucilage, respectively. These results will be helpful in selecting suitable drying methods depending on the functional and rheological properties desired of the chia and psyllium mucilage in a food product.
RESUMO: Este estudo teve como objetivo avaliar a influência dos métodos de secagem (secagem em estufa a 50 °C e liofilização) sobre a composição centesimal, características funcionais e propriedades reológicas da mucilagem obtida a partir de sementes de chia e casca de psyllium. Os resultados mostraram que a alta temperatura de secagem em estufa reduziu o teor de fibras, a solubilidade, a atividade da emulsão e a estabilidade da emulsão das mucilagens. Todas as amostras apresentaram comportamento pseudoplástico, com o melhor ajuste produzido pelos modelos Heschel-Bulkley e Power Law das mucilagens de chia e psyllium, respectivamente. Estes resultados serão úteis na seleção do método de secagem adequado, dependendo das propriedades funcionais e reológicas desejadas das mucilagens de chia e psyllium.
ABSTRACT
Abstract Red beets is rich in phenolic acids and has high antioxidant capacity, and can be used to produce a natural dye. This study evaluated the effect of pH (3 to 6) on the stability of red beet extract microcapsules, dried by freeze drying and spray drying and stored at room temperature. The microcapsules were produced using a combination of maltodextrin and xanthan gum as encapsulating agents and stored for 7 days. For all evaluated microcapsules, a degradation of betanin was observed, however, that degradation was independent of pH, with the exception of the sample with maltodextrin and dried by spray drying. The freeze dried products showed lower degradation constants and higher half-life (t1/2) when comparing with the spray dried samples. The microcapsules containing maltodextrin and xanthan gum, dried by spray drying, showed the highest change in the content of phenolic compounds after storage for 7 days. The color parameters showed a reduction for a*, and increase in b* and L*, for all samples during the storage time. In general, the microcapsules produced using maltodextrin and xanthan gum, and dried by freeze dryer, showed higher stability in terms of betanin content, phenolic compounds and color parameters during storage at different pHs.