Comparing the impact of heat on proteins from peas and soya the researchers found that the gel of the soya protein could be repeatedly heated without the gel losing its strength or flexibility. This was not possible with the pea protein gel.
Francesca O'Kane at Wageningen University discovered that proteins with a similar chemical structure behaved differently after heating, a crucial aspect in the development of new types of meat substitutes.
O'Kane used various proteins from peas and soya for her research. After heating the plant proteins formed a gel from which she could deduce the structure of the proteins after heating.
Although the pea protein legumin has a structure which is very similar to the soya protein glycinin, O'Kane discovered clear differences between the two proteins after heating.
The gel of the soya protein could be repeatedly heated without the gel losing its strength or flexibility but this was not the case for the pea protein gel, due to its unusual spatial structure. She reports that on repeated heating this gel became increasingly stiff.
"The greatest stumbling block in the design of foodstuffs using non-animal proteins is the unpredictability of the final product's structure, the so-called texture," say the researchers.
O'Kane used several proteins from peas to map the behaviour of plant proteins. She followed the molecular structure of the proteins in three stages: the unfolding during heating, the aggregation after heating and the eventual formation of a network, in which the proteins formed a gel. The formation of the gel provides a model for how proteins aggregate.
In the future, the researchers want to establish whether the behaviour of proteins from peas at the molecular level also takes place on a larger scale. In addition to this they are investigating the interactions of proteins with other food components.
"It will then be possible to understand how the texture of meat substitute products changes upon heating, and more importantly, it will be possible to predict this in advance," report the scientists.
The research is part of the NWO research programme 'Protein Foods, Environment, Technology and Society' (Profetas) that is examining the possibilities for a fundamental shift in diet.
Researchers from various disciplines are investigating whether the substitution of meat by foodstuffs based on plant proteins is favourable for the environment. They are also investigating whether these changes are technologically and socially feasible.
Per capita consumption of soya-based drinks and desserts in Europe has grown by over 20 per cent in 2002 and is currently as large (valued at €1.3 billion) as the per capita consumption of meat-free and tofu products in Europe, according to a recent report from Netherlands-based organisation Prosoy.
The popularity of soyfoods is being driven by growing consumer awareness of soy's health benefits, particularly its role in lowering cholesterol. In the UK, the Joint Health Claims Initiative supports the use of a health claim stating that when at least 25 grams of soy protein a day is consumed as part of a diet low in saturated fat, it can help reduce the risk of heart disease.
Food manufacturers are responding to this growing awareness by developing new formulations for food and beverage products using a raft of new ingredients. Soya product suppliers active in Europe include Israeli firm Solbar, Acatris, Degussa Food Ingredients, Cargill and S. Black.