Impacts of milk fat globules on the physicochemical properties of stirred yogurt

Milk proteins play an essential role in yogurt manufacture, by adsorbing onto the fat globule interface. This study aims to clarify the impacts of milk fat globules on the physicochemical properties of stirred yogurt, by modifying the particle size distribution of fat globules in reconstituted milk. The results show that high-pressure homogenization increased the association between milk proteins and milk fat globules. The zeta potential and protein surface hydrophobicity of reconstituted milk samples increased. Stirred yogurt prepared with reconstituted milk homogenized at high pressure (≥ 20 MPa) exhibited a fine mesoscopic structure with higher water holding capacity and apparent viscosity. Based on transmission electron microscopy and atomic force microscopy, the milk fat globules tended to form effective connections with casein micelles, giving the yogurt a finer network structure and higher viscosity. These findings reveal that controlling milk fat globule size can effectively improve stirred yogurt quality.