Effect of carboxymethylcellulose and xanthan gum on rheological profile of dried maize masa

Maize masa was obtained using a traditional nixtamalisation process, and then freeze-dried to obtain dried masa. Both masa dispersions with 10%(w/V) total solids control (DM), masa dispersions mixed with carboxymethylcellulose (CMC) and xanthan gum (0.2% and 0.5%(mass fraction) gum solids) named masa with hydrocolloid (DM_H) were prepared by distilled water, and the rheological properties were tested. Dynamic oscillatory measurements were performed on a TA Instruments AR-1000 Controlled Strain Rheometer using a parallel plates system with a diameter of 60 mm and a gap of 200 μm. The strain amplitude sweeps were run from 0.1% to 3 % in the 1st stage (at 25 °C) and from 0.1% to 5% in the 2nd (at 90 °C) and 3rd stages (at 25 °C) of a heating (at 25-95 °C, stage 1) - cooking (95 °C, 10 min, stage 2)-cooling (95 °C to 25 °C, stage3) kinetics at a frequency value of 1 Hz. Once the linear viscoelastic region was found, the frequency sweeps (0.1-10 Hz) were run when a constant strain value of 0.3% was used in the 1st and 2nd stages and of 0.5% in the 3rd stage of the kinetics. All masa samples (DM and DM_H) behave as viscoelastic gels with G′ (elastic modulus) >G′ (viscous modulus), when all masu samples are subjected to three stages of heating-cooking-cooling kinetics using increments in the moduli values as progressing from one stage to another. Overall, the hydrocolloid addition decreases both moduli values, probably by interfiring with the masa components structure in an aqueous environment. The smoothest gel is the one of DM_H-xanthan with 0.5% (mass fraction) of solids.