Effects of protein concentration and CaCl2 on cold-set thickening mechanism of β-lactoglobulin at low pH

Effects of protein concentration and CaCl2 on the cold-thickening mechanism of a pH-modified β-lactoglobulin (β-lg) ingredient were studied. Flexible fibrillar networks were formed at pH 3.35, and more branching was observed with an increase in CaCl2 equating to an increase of ionic strength (I) of 60 mm. This increase in ionic strength of β-lg solutions led to an increased conversion of monomers to aggregates (>106 Da), especially at concentrations above 6.9% (w/w), the critical concentration (Cc) for this modified protein system. A more connected flexible fibrillar network was observed following freeze-drying, with increased viscosities of rehydrated modified powders as compared with modified solutions prior to drying. A small increase in I (∼10 mM) at concentrations greater than Cc resulted in improved thickening with similar network characteristics and thus provided an option for manipulation of protein and CaCl2 concentration to obtain improved thickening behavior.