What makes jelly wobble?

Have you ever wondered what makes jelly wobble? If so, a food scientist has looked into the science behind what makes one of our favourite childhood foods move so curiously.

The research is reported in the latest edition of the Royal Society of Chemistry's journal Soft Matter.

Professor Eric Dickinson, at the University of Leeds, has prepared guidelines for predicting the texture and consistency of semi-solid foods - and says the reason they behave in this way is because all contain 'colloidal' ingredients.

Colloidal foods are ones in which very small, finely divided ingredients remain dispersed in the liquid (water in the case of jelly) for a long time due to their small size and electrical charge.

He said: "Jelly, salad dressings, margarines and sauces are semi-solid foods containing combinations of colloidal ingredients.

"Interactions between proteins, sugars and surfactants in these mixtures determine their textures and consistencies."

Motivated by a desire to understand these interactions and predict their effects, Prof Dickinson used theoretical modelling and computer simulations to work out how they modified texture and consistency - for example during mixing of cream toppings or baking of cakes.

The Soft Matter article was based on Prof Dickinson's Rideal Lecture, delivered in London in the spring, at a symposium on Colloid Science in mixed ingredients organised jointly by the SCI Colloid and Surface Chemistry Group (UK) and the RSC Colloid and Interface Science Group (UK).

Vic Morris, an expert in colloid science at the Institute of Food Research in Norwich, said: "The research is significant for the development and use of computer simulations to describe and predict the behaviour of colloids in foods." 

The end applications of the research will be in helping substitute ingredients in foods, so that nutritional value can be improved without the loss of texture or consistency.

with thanks to Nina Athey-Pollard for the original article.