Efeito de alguns parâmetros operacionais nas características físicas, físico-químicas e funcionais de extrusados da farinha de batata-doce (Ipomoea batatas) / Effect of some extrusion parameters on physical, physicochemical and functional properties of sweet potato flour extruded products

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The sweet potato is a vegetable of great energetic potential with high starch content. It can to be processed through extrusion which is efficient on the processing of starchy foods. In this work the effects of extrusion parameters on sweet potato extrudates and flours characteristics were studied. The properties evaluated in extrudates were expansion index (EI) and texture (hardness). The physical, physico-chemical and functional properties assayed in the extrudated flours were: water absorption index (WAI), water solubility index (WSI), color (L*, a*, b*) and color difference (CD), degree of gelatinization (DG) and pasting properties as initial viscosity (IV), raw peak (RP), breakdown (BD), setback (SB), cold viscosity (CV) and final viscosity (FV). The study was carried out by using Response Surface Methodology through an incomplete factorial design 33 with 3 levels and 3 independent variables: moisture content (15, 18, 21%), extrusion temperature (100, 120, 140oC) and screw speeds (180, 210, 240 rpm). The moisture content and extrusion temperature significantly affected expansion index of the extrudates.There was no influence of the parameters studied over extrudates hardness. The extrudates EI increased with the high extrusion temperature and low moisture content when the screw speed was medium. It decreased with the low moisture and temperature and at higher moisture content and temperature. The changes in independent variables did not result in significant regression model to extrudates hardness. The technological characteristics of extruded flours, WAI, WSI, SB and DG, did not present significant regression model to the parameters studied. The flours presented DG varying from 82.0 to 99.7%. The L* (lightness) component increased and value a* decreased with the increase of the moisture content until 20-21%. The color difference (CD) and parameter b* increased as the moisture content decreased, independent of the extrusion temperature. The IV, RP and BD values decreased with the increase the moisture until 20-21%. The flour FV decreased as srew speed increased. The study showed that is viable the production of sweet potato extrudates with good characteristics using the independent variables of the process.

ASSUNTO(S)

sweet potato extrusão flour - physic-chemical analysis viscosidade processing of foods viscosity starch batata-doce extrusiion farinha – análise físico-química amido processamento de alimento

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