Résumé
The relationship between the content of N-acetylneuraminic acid residues of micellar kappa-casein and acid coagulability of milk was investigated. At 30 degreesC, partial deglycosylation of micellar kappa-casein does not significantly affect the content of micellar proteins, micellar surface charge, and micellar solvation. Casein micelles modified by the release of part of the N-acetylneuraminic acid residues showed a shorter acid gelation time, a higher rate of gel strengthening, and a higher final firmness. This enhancement in the gelation ability of the neuraminidase-treated casein micelles of milk should appear as the result of increase in number of hydrophobic sites on the surface of casein micelle due to enzymatic deglycosylation of micellar kappa-casein.