Résumé
Casein micelle stability and reactivity were assessed on milk subjected to reversible acidification by carbonation. Pressurised CO
2 was injected at 4
°C, leading to controlled acidification from 6.63±0.02 to a target pH (5.5 or 5.2). After holding the pressurised milk under these conditions for 15 or 60
min, the pressure was released and the milk pH returned to its initial value under stirring and vacuum degassing. Upon CO
2 treatment, calcium and protein partition, zeta potential and size of casein micelles were restored directly after neutralisation. The rheological properties of the gel obtained by acid coagulation of CO
2-treated milk did not change as a result of carbonation. Micelle hydration increased after neutralisation and during storage. Milk buffering capacity in the pH range of 4.5–5.5 decreased after neutralisation of milk acidified by carbonation, but increased during chilled storage of this milk. Holding time of carbonated milk at low pH was found to have no impact on the physicochemical characteristics of casein micelles and the rheological properties of the gel obtained by acid coagulation of this milk.