Abstract: In this study, the stability of cow’s milk with fat replacement by soybean oil bodies (SOB) was investigated under different environmental conditions. Moreover, the effect of replacing milk fat with SOB or anhydrous milk fat (AMF) on the stability of milk stability and yogurt quality was evaluated. The results showed that the particle sizes of milk with fat replacement and raw milk were larger at pH 2.0 and 4.0 than at other pH values. The particle size of SOB milk was significantly higher than those of AMF milk and raw milk at pH 2.0–10.0 (P < 0.05). At NaCl concentrations ranging from 0 to 500 mmol/L except for 200 mmol/L, significantly higher particle sizes were observed for SOB milk than AMF milk (P < 0.05). However, all three milks were stable without droplet aggregation. Under different heat treatments, they were very stable. After 6 h of fermentation, SOB milk reached the ideal pH (about 4.5) of yogurt, while a longer fermentation period was required for AMF milk and raw milk. The viscosity of fermented SOB milk was significantly higher than those of fermented AMF and raw milk (P < 0.05), but they had similar good sensory and texture properties. This study can provide a reference for the application of soybean oil bodies as a substitute for milk fat in dairy product processing.

Key words: soybean oil bodies; anhydrous milk fat; fat replacement; stability; yoghurt