To emphasize the coffee flavor, many milk coffee beverages contain coffee extracts; these are the so-called "rich milk coffee" beverages. When the content of the coffee extracts increases, milk coffee beverages become unstable. The milk ring formation, or oiling off, is accelerated in these kinds of drinks. We prepared a "rich milk coffee" beverage and studied the stability of the emulsion. We also investigated the influence of the food emulsifiers on the stability of the emulsion. We tried to test the emulsifier system in order to improve the emulsion stability. When the milk coffee beverage with a low light value for the roasted coffee beans sterilized by UHT was stored at a low temperature, the milk component strongly separated. We found that the sucrose monoester with a high HLB and diglycerol monoester accelerated the milk separation, and the decaglycerol monoester controlled the milk separation. We discussed the milk separation mechanism and showed that maintaining the hydration of the hydrophilic group in the rich milk coffee beverage was related to the combination of emulsifiers that control the milk separation. (C) 2015 Elsevier Inc. All rights reserved.