Leatherhead project to analyse chewed-up food

In February the consultancy floated the idea of a collaborative industry project to look at textual and structural change in low fat foods during chewing.

Kathy Groves, food microscopist and project leader at Leatherhead Food International, told FoodNavigator.com the idea has generated considerable industry interest, and the consultancy has now put together a proposal on how exactly it will delve into the area.

The idea for the research stemmed from work on food structure, she said, as past research into texture and mouthfeel has centred on what ingredients are used to create the effect.

But while it is important how a food product starts out before it is put in the mouth, it is just as relevant to consider how it changes in the mouth.

Low fat perception​

The issue is particularly pressing when it comes to development of low-fat products, since the distribution of fat can have a big impact on how the product is perceived as it is eaten.

According to Groves, consumers tend to think “low fat foods are ok, but they are not the same as full-fat”​.

She explained that when you put a fat-based product in the mouth, the emulsion breaks off and costs the mouth with fat. This is what gives the fatty, creamy mouthfeel.

“Fat does something in the mouth that we don’t know about. Little is known about how food breaks down, and where to locate ingredients.” ​

For instance, would it help the mouthfeel of low-fat products if a layer of fat were put around each mouthfeel?

“We want what fat is there to do the same as it does in a higher-fat product,”​ said Groves.

She added that the same theory could hold true for salty and sweet products, as the first ‘hit’ pre mouthful is really all you need.

“You don’t need it throughout the food,”​ she said.

Chew it up, spit it out​

For the full research proposal, Groves said the challenge has been to design a project that will appeal to a wide range of food interests – that is, covering snacks, beverages, etc – but without causing competitive issues between the participants.

She has chosen to food models – one chewy with a starch gel structure, and one crunchy with a biscuit structure – and to change the levels of hydrocolloids, sugars and fats.

A trained panel of testers will chew the foods and describe the sensation using a lexicon of texture terms. The researchers will then observe the structural changes.

“They will chew it, spit it out, and we will look at it,”​ she said.

In addition, the researchers will use equipment that mimics the chewing process, and look at aspects like sheer (the pulling apart and rubbing together of particles) under the microscope.

“We will also look at similar off-the-shelf biscuits, chews, and softer foods like mayonnaise,”​ she said.

Groves explained that, when chewed foods are inspected under the microscope, it is possible to see a difference at a cellular level.

“You can see quite a big difference just on the first bite.” ​

For instance, with a crunchy apple like the Granny Smith, it is possible to see inside the cells, as the bit cuts straight through the rigid cell walls. With a softer apple, on the other hand, like a Golden Delicious, the bite goes between the cells, as that is where the weak point is.

Collaborative funding ​

Groves said that Leatherhead has already held a meeting with interested participants, and the consultancy is asking for a contribution of between ₤10,000 and ₤15,000 per company.

The depth of the project depends on how many companies sign up.

“We could carry it out for ₤50,000 or ₤60,000, or for ₤100,000​,” said Groves.

The collaboration partners will then have a period of exclusivity to use the findings of the project before they are made public to the wider industry.