The protein composition and emulsifier adsorbed at the oil/water interface are very important in controlling
the stability of fat droplets. In this study, the effect of soy-to-milk protein ratio in the presence or
absence of sucrose fatty acid ester on the stability of ice cream emulsions was investigated. Parameters
such as particle size distribution, dynamic surface pressure, surface protein adsorption, rheological
properties and crystallization behavior of fat in the bulk and emulsified state were determined. The
results indicated that destabilization of fat droplets depended on the protein surface adsorption activity,
proteineprotein and protein-sucrose fatty acid ester interactions at the interfacial layers. The addition of
soy protein isolate significantly increased the flocculation of fat droplets during pasteurization. Emulsions
containing sucrose fatty acid ester were distinguished by a higher partial coalescence degree (19.8
e252.7%) of fat droplets compared to emulsions without sucrose fatty acid ester (5.5e37.3%) with the
same protein composition. The particle size and adsorbed protein results showed a direct negative
relationship between protein surface coverage and partial coalescence degree for emulsions with sucrose
ester. The increased protein coverage when the soy-to-milk protein ratio was above 5:5 probably resulted
from the enhanced proteineprotein interactions. The supercooling needed for detection of crystalline fat
was found to increase with the increase in soy-to-milk protein ratio up to 7:3. However, no significant
correlation was found between the proportion of crystallized fat content and partial coalescence degree.
These findings provided a theoretical basis for controlling the stability of aerated food emulsions with
soy/milk protein mixture.