Influence of concentration and pH in caseinomacropeptide and carboxymethylcellulose interaction

Aqueous systems with caseinomacropeptide (CMP), with or without carboxymethylcellulose (CMC), at different concentration and pH (2, 4 and 6.5), were analyzed. Strong evidence of interaction between the peptide and the polysaccharide was found at all pHs, even those close to neutral. All samples formed gel at pH 2. The formation of soluble and insoluble complexes occurred at pH 4. FTIR technique with Fourierʹs transformation was employed to analyze changes in the system. Results show visible changes in bands at different pHs and concentrations. Since amide I band had highest modification due to pH rather than to CMC, the interaction between CMC and CMP may be electrostatic. The rheological behavior was also changed and shifted from shear-thickening to shear-thinning in the presence of the polysaccharide.