Theory could reduce lumps in powdered foods

Scientists from Nestlé say they’ve developed a theory that will predict the way soluble substances will dissolve in water with greater accuracy than ever before. The theory could help food manufacturers develop food and beverage products that give a smoother texture with fewer lumps when mixed with liquid.

Working with the École Supérieure de Physique et de Chimie Industrielles (ESPCI) in France, scientists from the Nestlé Research Center in Lausanne have discovered a novel physical mechanism by which water wets and then dissolves soluble solids.

In the study, the scientists examined the contact between a droplet of water and a thin layer of a long-chain sugar coated on a smooth surface. The various sugars used in the study were non-crystalline ‘amorphous’ sugars that lack an organised molecular structure and, as such, can easily undergo a change of state.

Two synchronised video cameras simultaneously measured the angle of contact, as well as the velocity, of the water droplet as it spread over the surface of the sugar layer. The absorption and diffusion of the water in the sugar coating were also measured by analysing the colour changes of reflected light.

According to the researchers, this study shows for the first time that the manner in which a water droplet spreads over a non-crystalline substrate, such as maltodextrin, strongly depends on the amount of water absorbed and on the softness of the substrate in the immediate vicinity of the water droplet.

The research will help master the dissolution of powdered food products, the researchers say. The theory will allow the conditions of dissolution of different soluble substrates to be predicted with greater accuracy.

The study has been published in the journal Physical Review Letters.