Chia seeds ( L.) when immersed in water, produce a highly viscous solution due to the release of mucilage, high molecular weight complex carbohydrates with wide application in the food industry. Thus, this study involve development of method for extracting mucilage from chia seed based on mechanical process and low temperature. The method involve extraction by cold pressing and drying by freeze-drying, which was compared to the traditional hot extraction method. The chia seed mucilage cultivated in Brazil was extracted successfully using the previously mentioned extraction method. Rheological analysis including thixotropy, flow curve and frequency sweep of mucilage was done. Microstructure was examined by scanning electron microscopy. The optimal process at 27 °C gave yield of 8.46%. The rheograms showed that the apparent viscosity decreased with increase in shear rate and this effect was most notable in the dispersions obtained by cold extraction and with high concentrations. The gum obtained using CE presented higher values for thixotropic behavior. The storage modulus (G') was consistently higher than the loss modulus (G″) and the data indicated formation of 'weak gel' structure of the dispersions. SEM indicated macroscopic fibrous structure of mucilage obtained through cold extraction process, indicating that the macromolecular network formed by fibrous material contained in mucilage maintained its structure in the process of deep freezing and freeze-drying.

ABSTRACT. This work aimed to evaluate the physicochemical characteristics and enzymatic activity of "Sabará" jabuticaba fruits, which were cultivated in Lavras, Minas Gerais State, Brazil, at different maturation stages. The fruits were harvested and separated into five different stages: totally green fruit, fruit with incipient pigmentation, fruit with a light purple predominance, totally purple fruit and totally dark purple fruit. These fruits were physicochemically analyzed and evaluated for polygalacturonase enzymatic activity. Chlorophyll degradation and the synthesis of anthocyanin on fruit rinds were observed, as well as the degradation of the cell wall and its consequent softening. In the pulp, increased soluble solids, pH and sugars were observed, while acidity decreased as maturation progressed.Keywords: Myrciaria jaboticaba, pectin, polygalacturonase, chlorophyll, anthocyanin.Caracterização de Jabuticaba 'Sabará' em diferentes estádios de maturação RESUMO. O presente trabalho teve como objetivo avaliar as características físico-químicas e de atividade enzimática de jabuticabas 'Sabará' cultivadas em Lavras, Estado de Minas Gerias, Brasil, em diferentes estádios de maturação. Os frutos foram colhidos e separados em cinco diferentes estádios: frutos totalmente verdes; frutos com início de pigmentação; frutos com predominância roxo claro; frutos totalmente roxos e frutos totalmente roxo-escuro. Em seguida, os frutos foram submetidos às análises físico-químicas e a atividade da enzima poligalacturonase. Foi possível observar a degradação da clorofila e a síntese de antocianinas na casca dos frutos, bem como a degradação da parede celular e o conseqüente amaciamento dos mesmos. Na polpa, observou-se um aumento de sólidos solúveis, pH e açúcares, bem como uma diminuição da acidez à medida que o grau de maturação foi aumentando.

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