Ethanol stability of casein micelles cross-linked with transglutaminase

The influence of transglutaminase (TGase)-induced cross-linking on the ethanol stability of skimmed milk was investigated. The stability of milk against ethanol-induced coagulation increased in sigmoidal fashion with milk pH (5.0-7.5) for all samples; ethanol stability also increased upon incubation (0-24h) with 0.05 g L-1 TGase at 30 degrees C. In untreated milk, addition of ethanol induced a collapse of the polyclectrolyte brush Of K-casein on the micelle surface.. thereby facilitating micellar aggregation. Dynamic and static light scattering measurements indicated that in TGase-treated milk, the ethanol-induced collapse of the polyelectrolyte brush was far less than in untreated milk, suggesting that the increased ethanol stability of TGase-treated casein micelles is caused by the cross-linking of the polyelectrolyte brush on the micellar surface. (c) 2006 Elsevier Ltd. All rights reserved.