Cold-set whey protein microgels as pH modulated immobilisation matrices for charged bioactives

The ability of cold-set whey protein microgels to function as pH-sensitive immobilisation matrices for bioactives was investigated. A pH dependent interaction was confirmed between the microgels and charged bioactives and this binding was impeded by the presence of competing ions in the solution, suggesting an electrostatic interaction. The use of a computer generated prediction model for the pH-dependent association of the microgels and further bioactives (including cationic and anionic peptides) was validated. The prediction model was efficient at determining the pH at which the maximum microgel–bioactive interaction occurred. This study highlights the capabilities of these food-grade whey based microgels as matrices that enable the immobilisation of a variety of bioactives by a charge interaction, and shows the potential for these matrices to function as smart delivery systems, in which uptake and release of bioactives is facilitated by environmental pH change.