While previous research has found that smaller oil droplets increases expectations of satiation and satiety, the current study, led by Aaron Lett from the University of Birmingham and published in Appetite Journal, looked specifically at food intake and appetite.
They found that subjects who consumed a pre-load drink with smaller oil droplets ate more than 12 % less afterwards – despite no reported differences in taste or expectation of food intake between the two.
“[Our] findings indicate that satiety can be significantly enhanced without producing significantly perceivable differences in sensory properties,” they wrote.
“Therefore, using the same formulation and by introducing a processing step which results in a smaller average droplet size (for example, higher shear/pressure processing), emulsion based liquid food products can be produced with enhanced effects on satiety, but with a very similar sensory profile as the original product, allowing functional redesign unbeknownst to the consumer."
Lett et al. have called for future research to focus on whether such differences in satiety still ring true after repeated consumption of the product. “Such findings would be important in understating whether participants modify their satiety response, as a result of a learning effect between the ingested energy content and preparatory cognitive and sensory influences.”
Thirty-four healthy men took part in the study. Three hours after eating a fixed portion breakfast, they were given one of two emulsion pre-load drinks which were equal in nutritional content, providing around 282 kcal, 30 g fat, 2 g protein, and 4 g carbohydrate, but which contained either 2 or 50 μm oil droplets. Participants were asked to rate the emulsion drink for thickness, slipperiness, smoothness, creamy mouth feel, overall creaminess, liking, expectation of hunger in 1 h time (satiety) and expectation of fullness immediately (satiation).
This was then followed by a pasta lunch during which they could eat ad libitum. The researchers found that total lunch intake was 12.3% (67.7 g or 62.4 kcal) lower for those who had drunk the 2 μm emulsion – a significant difference, they wrote.
Source: Appetite Journal
First published online 4 September 2015, doi:10.1016/j.appet.2015.08.043
"Emulsion oil droplet size significantly affects satiety: A pre-ingestive approach"
Authors: A. M. Lett, J. E. Norton, M. R. Yeomans