As fat replacer producers have learned, a widely-recognised reason for the relatively slow take-up in low fat or fat-free foods by the consumer is the simple fact that the food products fail to satisfy the mouth - either through taste or texture. The research undertaken by Doctors Rolls and de Araujo at Oxford university could have wide implications for a food industry eager to take a slice of the growing trend in health-promoting food.
"Which properties of fat are rewarding for the brain ?" Dr. De Araujo questions FoodNavigator.com, voicing the thrust behind the team's recent research into how the control of appetite and hunger is related to the consumption of fat.
Examining how our brains respond to different food textures, the scientists found that fat led straight to the pleasure zone.
"We believe there are attributes of fat which activate 'rewarding areas' in the brain. But these areas can not be accounted for by viscosity," said de Araujo.
This suggests that there are special properties in fat that underlie our overall desire for fat, purport the two scientists.
The researchers believe it is too early to hypothesise about the 'special properties'and that future studies will focus on improving the understanding of how the mouth understands fat.
Their findings stem from research on 12 participants aged between 23 and 41 last year. The researchers placed the participants inside a functional magnetic resonance imaging machine and fed them differently textured foods through a tube. They watched subjects' reactions as they consumed three different stimuli - a tasteless cellulose (carboxymethyl) mixed to various thickness, sucrose, and a bland vegetable oil.
We knew the viscosity of fatty oil so we prepared the cellulose stimulus with the same viscosity to fat. We found that the reward areas of the brain were particularly stimulated by the fatty oil, but not by the cellulose with the same viscosity, said de Araujo. Findings that suggest the pleasure that fat stimulates in the brain is due to more than its texture and that the brain builds a picture of what is in the mouth based on both taste and texture.
"It appears there is a region in the human brain that builds a representation of the combined taste and texture," added de Araujo.
The implications for the food industry lie in the understanding of brain activations stimulated by properties in fat and a clearer idea of how these 'rewarding areas' arise. If scientists can unravel the brain activations provoked by eating fat, they can then set to work designing fat substitutes that can activate, indeed mimic, these same stimulations.
While the consumer continues to show a strong interest in eating healthier foods the market for low fat or fat free foods is still ripe for the picking. In the US alone, market analysts Freedonia predict that fat replacers will grow over seven per cent annually to the end of 2004, with combined demand for artificial sweeteners and fat replacers in the US peaking at $1.2 billion in 2004.
But players in the market are not only held back by taste and texture challenges, a recent Frost & Sullivan report highlights how the industry has been damaged by negative publicity linked to the fat replacer Olestra.
"Introduced in 1996, Olestra is a fat-based fat replacer approved for use in savoury snacks such as potato chips and crackers. Thought to have great potential, clinical tests found that Olestra consumption reduced absorption of important nutrients and could cause abdominal symptoms in some consumers. Consequently, the Olestra market plummeted. Now participants are faced with managing the backlash against similar products, " said the report authors.
The recent findings from the researchers in Oxford hold the potential to reverse this blacklash, suggesting the direction that future research on low fat foods could take.
Fat replacers used by the food industry today revolve around the major types - carbohydrate-, protein-, and fat-based fat replacers. Modified whey protein concentrate and microparticulated protein fall into the protein-based category, while cellulose, dextrins, fibre, inulin, gums, maltodextrins, modified food starch - and more - come under the carbohydrate-based replacers. Fat based fat replacers include emulsifiers, lipid analogs and salatrim. Ingredients players involved in the fat replacer market, of which there are many in this crowded marketplace, include Danisco, CP Kelco and Orafti.
Full findings of the Rolls and de Araujo study are published in the March issue of the Journal of Neuroscience, 24, 3086 - 3093, (2004).