Comportamento reológico de géis de mucilagem do Cará-roxo (Dioscorea trifida)

Abstract

Mucilages are of great interest in the food industry for alternating life with products such as oils and fats, among other advantages. And tubers have been studied for such applications because of their shared rheological properties for applications and nutritional values already known. In this work, the mucilages of cará-roxo in the form of gels were investigated. The semi-solid state was achieved with the addition of maxy maize, a commercial product basically composed of amylopectin. Different additions of cará-roxo (1, 3 and 5%) were studied in the composition of waxy maize gels and after preparation times 0, 24, 48 and 72h. The rheological tests in steady state show that the gels present pseudoplastic behaviors being suitable for the adjustments the mathematical models of Law of Power and Herschel-Bulkley. The compositions of 3 and 5% of cará-roxo showed apparent viscosities higher than the gel composed only of waxy maize. With the time study, it was found that at 0h the gels show shear strengths similar to the constant deformation rates, but after 72h the 3% gels reached apparent viscosity levels of 1500 Pa.s. The behaviors in this study were similar in pure waize and 1% mucilage. By the characterizations of FTIR and XRD, it can be verified that the gels of purple yam have amylose and amylopectin that changed their crystallinities with the changes in compositions. Due to the RVA curves, the waxy maize paste has improved its paste properties, leading to a high level of peak viscosity in the concentrations of 3 and 5% of purple yam, the latter being a modification of the behavior of the RVA curve. The changes that occurred were attributed to changes in the amounts of amylose and amylopectin, as well as decreases in crystallinity.