Nestlé scientists have said they are the first to develop a theory that predicts with greater accuracy the way in which certain soluble substances will dissolve in water. The theory could enable the creation of powdered food and beverage products that produce fewer lumps and a smoother texture when mixed with liquid.
Working with the École Supérieure de Physique et de Chimie Industrielles (ESPCI) in France, the company’s researchers used previously unavailable technology to observe at microscopic range the interaction between a drop of water and a thin layer of sugar.
The study is published in the journal ‘Physical Review Letters’.
Optimal dissolution of powders is critical for providing consumers with a smooth and appealing beverage that ensures adequate delivery and uptake of important nutrients. Unfortunately, incomplete dissolution, with concomitant formation of lumps, can arise during the development of new, nutritious powdered food products. The mechanisms underlying the problem are complex and have, hitherto, been poorly understood.
Successful dissolution of a powder is dependent on the physical and chemical nature of both the substrate and the solvent. In the current 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 sugarcoating were also measured by analyzing the colour changes of reflected light. 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 current work is an important step towards mastering the dissolution of powdered food products. The quantitative theory which was developed will allow the conditions of dissolution of different soluble substrates to be predicted with greater accuracy. As a consequence, this will allow the development of a wider range of products that are not only nutritious but more pleasurable for the consumer.
