Influencia de la concentración, del pH y de la presencia de sal en el comportamiento reológico de disoluciones acuosas de derivados de celulosa

Effects of gum concentration (C), pH and presence of salt and of their interactions on the flow characteristics of solutions of four cellulose gums two hydroxyropylmethyl (K100LV and K4M), a methyl (A4C) and a carboxymethyl- (7HFD) were studied in order to obtain information related with their possible use in formulating reduced calories fruit nectars. Twenty. solutions of each gum were prepared following a factorial design: five gum concentrations (0.10 to 0.50% w/v for K100LV, K4M and A4C, and 0.10 to 0.30% w/v for 7HFD), two pH values (3.S and 6.0) and two salt levels (0 and 0.50% w/v). K100LV and A4C solutions showed Newtonian flow for C≤0.30% and K4M for C= 0.10% and slightly pseudoplastic at higher C. 7HFD solutions were pseudoplastic at all gum concentrations. Viscosity of K100LV solutions depended only on gum concentration while that of A4C solutions depended on gum concentration and on presence of salt (a=0.05). Consistency index (K) of K4M solutions depended only on gum concentration and that of 7HFD solutions depended on gum concentration, on pH, on presence of salt and on pH-salt interaction. The interaction between concentration and presence of salt showed a significant effect on pseudoplasticity (n values) of K4M solutions but only the effect of salt was significant on this parameter in the case of 7HFD solutions