25 resultados para RVA


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This research had as objective to evaluate the effect of extrusion temperature and screw speed on physical and rheological properties, as well as, the sensory acceptance of cassava and passion fruit snacks produced in single-screw extruder. A central composite design with 11 treatments was used, considering as dependent variables: expansion index (EI), specific volume (SV), water solubility index (WSI), water absorption index (WAI), color (L*, a*, b*) and pasting properties (RVA). The products were flavored and analyzed for global acceptance. The results showed significant effects of temperature and screw speed on the dependent variables. The chocolate flavored snacks obtained good acceptance.

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Peruvian carrot and cassava starches were ground in a ball mill for 4, 8, 16, and 32 h and their structural and physicochemical characteristics were determined. Results obtained from HPAEC-PAD, GPC, and amylose content indicated a breaking of hydrogen bounds and α-(1 [RIGHTWARDS ARROW] 6) linkages of the starch molecules after treatment. X-ray diffractograms showed that the milling provided a reduction in the crystalline area of the starch granules. Most of the starch granules displayed agglomeration after 4 h of milling, when observed under a scanning electron microscope, and after 16 h a shapeless mass was observed for Peruvian carrot starch. Solubility and water absorption capacity of the starches increased with an increase in the milling time, while RVA profiles showed a progressive reduction of peak, breakdown, and final viscosities, as well as the development of initial viscosity. Gelatinization temperatures and enthalpies were reduced. Prolonged ball milling accelerated the enthalpy relaxation in both starches. These results confirmed a partial gelatinization of the starches, which was 82.6% for Peruvian carrot and 65.4% for cassava starches after 32 h of milling. The Peruvian carrot starch was more affected by the ball milling because of both its lower amylose content and the defects in its crystalline structure

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The objective of this work was to analyze the profiles of the concentrations of resistant starch and respective properties of paste of two cassava varieties with different development stages. For the evaluation of the profile of the concentration of resistant starch and paste properties, the starches of the cassava varieties were used IAC 576/70 and Fécula Branca, which were collected with different times of cultivation (10, 11, 12, 13, 14 and 15 months), and the use of these times were according the crop of cassava variety IAC 576/70. For the analysis of paste property the apparel was used RVA and for analysis of resistant starch the enzymatic method was used. The results showed for the paste properties happened significant differences among the two varieties of cassava starch, and in some months they there wasn't differences, and as the results of resistant starch happened differences among the starches the months of July and August, and as for the different development stages only the starch of Fécula Branca that happened significant differences.

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This work aimed to analyze the chemical composition and paste properties of cassava flours, from several producers and classifications, marked in different Brazilian cities. Flours were characterized to moisture, ash, fibers, protein, lipids, total sugars and starch. The paste properties were analyzed in RVA. The results showed significant differences to chemical components in cassava flours. The moisture ranged from 4.39 to 10.26, starch (82.19 to 88.90%), ash (0.48 to 1.07%), fiber (3.23 to 6.41%), protein (1.15 to 2.13%), total sugar (0.05 to 0.56%) and lipids (0.40 to 1.24). These differences can be due the variations of raw material and process. The paste properties of flours were different, with viscosity peak ranged from 73.33 to 387.08 RVU, breakdown (2.42 to 248.83RVU, final viscosity (154.92 to 275.5 RVU) and retrogradation tendency (50.75 to 132.5 RVU), showing the influence of kind of processing on flour viscosity.