EFFECTS OF CONCENTRATION, PH AND PRESENCE OF SALT ON THE RHEOLOGICAL BEHAVIOR OF CELLULOSE GUMS SOLUTIONS

Effects of gum concentration (C), pH and presence of salt and of their interactions on the flow characteristics of solutions of four cellulo se gums two hydroxypropylmethyl (K100LV and K4M), a methyl (A4C) and a carboxymethyl- (7HFD) were studied in order to obtain information rel ated with their possible use in formulating reduced calories fruit nec tars. Twenty, solutions of each gum were prepared following a factoria l design: five gum concentrations (0.10 to 0.50% w/v for K100LV, K4M a nd A4C, and 0.10 to 0.30% w/v for 7HFD), two pH values (3.5 and 6.0) a nd two salt levels (0 and 0.50% w/v). K100LV and A4C solutions showed Newtonian flow for C less than or equal to 0.30% and K4M for C = 0.10% and slightly pseudoplastic at higher C. 7HFD solutions were pseudopla stic 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 (alpha = 0.05). Consistency ind ex (K) of K4M solutions depended only on gum concentration and that of 7HFD solutions depended on gum concentration, on pH, on presence of s alt 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.