The colloidal behaviour and extent of lipolysis of various emulsions stabilized by whey protein and Tween were studied using the TNO Intestinal Model (TIM) extended with a purposely designed gastric compartment. The in vitro results suggest that creaming of a fatty layer in the gastric region causes a delay in fat entering the small intestinal region, delays and reduces the free fatty acid content in the small intestinal lumen and delays fat absorption. It was shown that controlling the pH with pig gastric juice instead of simulated gastric juice delayed creaming of the emulsions significantly, which resulted in faster gastric lipolysis. However, because the digestive conditions are not adjusted by physiological regulation mechanisms such as the regulation of gastric emptying by the detection of nutrients in the small intestine, care must be taken to translate these results to the in vivo reality. It is expected that the differences between the systems will be tempered by the physiological feedback regulation mechanisms of digestion.