Rheological properties of commercial whey protein samples from the MADGELAS survey

Thermally induced gelation of commercial whey protein samples from the Molecular Basis of the Aggregation, Denaturation, Gelation and Surface Activity of Whey Proteins (MADGELAS) survey has been studied in order to develop a current status report on their rheological properties. Solutions of 10% protein (w/v) were prepared in distilled water, 200 mM NaCl or 10 mM CaCl2 at neutral pH. Small-scare deformation of the samples was measured by dynamic oscillatory rheometry using a Bohlin CS Rheometer. Large-scale deformation at penetration mode was measured using a Texture Analyser (Stable Micro Systems, Surrey, UK). For solutions containing salts, there was a general trend for gel point to decrease and G' values to increase, the effect being more marked in the presence of NaCl. Similarly, force values at failure also tended to increase in the presence of salts. Results obtained with samples of similar protein composition dissolved in water were highly scattered, these differences being reduced in the presence of added salts.