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Scientists get right down to the pores of salty, fatty snacks

Two U.S. food scientists have found that by manipulating porosity during food manufacturing they can lower the salt and fat in some of our favourite snacks


Urbana, Ill. – Two food scientists may have found a way to change up salty and fatty foods and snacks for the better.

The food scientists – Youngsoo Lee and Pawan Takhar – from the University of Illinois say understanding and manipulating porosity during food manufacturing allows food processors to use less salt while still satisfying consumers’ taste buds.

FrenchFriesandKetchupThey also found that meticulously managing pore pressure in foods during frying reduces oil uptake, which can result in lower-fat snacks without sacrificing fried foods’ texture and taste.

The University of Illinois website says both scientists are experts in food engineering and professors in the College of Agricultural, Consumer and Environmental Sciences’ Department of Food Science and Human Nutrition.

Salty foods

Overconsuming salt is associated with high blood pressure, the development and severity of cardiovascular and bone diseases, kidney stones, gastric cancer and asthma, says Lee.

With many Americans suffering from these afflictions and because 70 per cent of the salt they consume comes from processed foods, Lee says he began to study the relationship between the microstructural properties of these foods and the way salt is released when it is chewed.

“Much of the salt that is added to these foods is not released in our mouths where we can taste it, and that means the rest of the salt is wasted,” he says on the website.

“We wanted to alter porosity in processed food, targeting a certain fat–protein emulsion structure, to see if we could get more of the salt released during chewing. Then food manufacturers won’t have to add as much salt as before, but the consumer will taste almost the same amount of saltiness.”

Increasing porosity also changed the way the foods broke apart when they were chewed, exposing more surface area and increasing saltiness, he adds.

“When foods crumble easily, we further reduce the amount of salt that is needed. Changing the number or size of pores in the food’s surface can help us to accomplish this,” he says.

Fatty foods

Takhar said that his porous media approach to understanding the behaviour of water, oil, and gas during frying will help create strategies that optimize the frying process, reduce oil uptake, and produce lower-fat foods.

The website says that articles Takhar publishes in academic journals feature page after page of complex mathematical equations that describe the physics involved in the transport of fluids and in textural changes in foods. These equations then guide the simulations that he performs in his laboratory.

“Frying is such a complicated process involving more than 100 equations. In a matter of seconds, when you put the food in the fryer, water starts evaporating, vapours form and escape the surface, oil penetration starts, and heat begins to rise while at the same time there’s evaporative cooling off at different points in the food. Some polymers in the food matrix may also change their state, and chemical reactions can occur. It’s not an easy set of changes to describe,” he says.

Within 40 seconds of frying, the texture of gently fried processed foods like crackers is fully developed, the scientist says.

“That’s the cracker’s peak texture. Any longer and you’re just allowing more oil to penetrate the food.

“A lot of frying research has focused on capillary pressure in the oil phase of the process, but we have found that capillary pressure in the water phase also critically affects oil uptake,” says Takhar.

Capillary pressure makes overall pore pressure negative, and that negative pressure tends to suck oil from inside. His simulations show when that pressure is becoming more negative.

“The trick is to stop when pore pressure is still positive (or less negative)— that is, when oil has had less penetration. Of course, other variables such as moisture level, texture, taste, and structure formation, must be monitored as well. It’s an optimization problem,” he notes.

When this exquisite balance is achieved, lower-fat, healthier fried foods are the result, he adds.

The scientists’ work has been published in the Journal of Food Science.

French Fries image courtesy of phasinphoto at FreeDigitalPhotos.net
Fried Onion Rings image courtesy of KEKO64 at FreeDigitalPhotos.net

 


Deanna Rosolen

Deanna Rosolen

Managing Editor, Food in Canada
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