Avaliação da viscosidade de carragenas comerciais

Abstract

The carrageenan is a polysaccharide that has many applications in the food industry due to their different characteristics. However, due to difficulty in obtaining it, standardization and quality control, different polysaccharides and salts can be added to lower the cost. In this study, we evaluated the rheological behavior (viscosity) of samples of carrageenan (Standard) in different ratios of 0.15, 0.20, 0.25, 0.30 and 0.35% (m / m) and ten Samples of different commercial brands 0.35% (w / w). To study the viscosity of these solutions, the increase in shear strength obtained was 60 rpm and 100 rpm with an additional 10 rpm every 3 min, on bends upward and downward. The solutions of carrageenan solutions at 0.15, 0.20 and 0.25% (w / w) showed no tendency to gelation whereas at 0.30% (w / w) was observed a tendency to gel formation. The carrageenan in concentrations of 0.15 and 0.20%, 0.25% and 0.30% (w / w) presented as a fluid dilatant. A 0.35% (w / w), we observed the formation of a weak gel, resulting in a thixotropic behavior. It was observed that the viscosity depends on the concentration of carrageenan. Of the ten samples analyzed, there was a difference in rheology between them, nine samples showed a viscosity of less than the standard carrageenan 0.35% (w / w), and in a sample, the formation of gel. In studying the viscosity of the carrageenan standard in concentrations equal to or less than 0.30% (m / m), we observe a behavior dilatant and maximum viscosity of 25 cP. When compared to the viscosity of commercial carrageenan samples at a concentration of 0.15% (m / m), we observed that three commercial samples showed very similar behavior to the carrageenan standard in all conditions examined, indicating that these samples were not added or were added amounts of other substances responsible for contributing viscosity of these samples. The opposite was observed at seven samples analyzed to have a completely different behavior of the viscosity of the standard carrageenan and commercial samples of the ten measured, was not examined due to its viscosity, gel formation, clearly indicating the possible addition of fillers. Thus, commercial 70% of carrageenans analyzed showed different behavior of the standard carrageenan, indicating the addition of other polysaccharides, salts or other substances used to influence the rheological characteristics of further studies are necessary to develop techniques for quality control of carrageenan.