Effect of carboxymethylcellulose and xanthan gum on the thermal, functional and rheological properties of dried nixtamalised maize masa

Maize masa was mixed with carboxymethylcellulose (CMC) and xanthan gum at 0.2 and 0.5% (w/w) solids and then freeze-dried for obtaining dried masa (DM) samples which were tested for chemical composition, thermal analysis, water retention capacity (WRC), solubility and rheological properties. The thermal properties of dried masa with hydrocolloids (DMH), showed a transition temperature higher than DM but lower enthalpies, in an interval between 80.5-81.6 degrees C and 5.4-11.4 J/g, respectively. Masa samples with hydrocolloids stored for 7 and 14 days, showed similar values of transition temperatures but different enthalpy values, being usually lower than that of the control. The WRC and the solubility of the DMH, were higher than those of the control. The addition of hydrocolloids to DM increased the viscosity expressed in Brabender Unities. All masa samples behaved as 'weak' viscoelastic gels, with G' (elastic modulus)> G" (viscous modulus), when subjected to a three stages of heating-cooking-cooling kinetics, with an increase in the moduli values as, the kinetics progressed. Overall the hydrocolloids addition decreased both moduli values. (c) 2005 Elsevier Ltd. All rights reserved.