Scientists from the University of Illinois have found that manipulating the porosity of food during manufacturing can affect its health benefits.

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"Six in 10 American adults either have high blood pressure or are on the borderline of this diagnosis largely because they eat too much salt," say the researchers.

"Six in 10 American adults either have high blood pressure or are on the borderline of this diagnosis largely because they eat too much salt," says study author Youngsoo Lee. "Overconsuming salt is also associated with the development and severity of cardiovascular and bone diseases, kidney stones, gastric cancer and asthma."

Up to 70% of this salt intake comes from processed foods, so Lee and colleagues were interested in studying the microstructural properties of processed foods to understand the way salt is released as the food is chewed.

Much of the salt that is added to food for flavoring is not released into our mouths, which means that a lot of salt content is wasted. The Illinois researchers wanted to see if they could release more salt during chewing. The implications of this would be no difference in terms of taste to the consumer, but food manufacturers would not have to add as much salt as before.

They attempted to do this by targeting a certain fat-protein emulsion structure to increase the porosity of the food. When the porosity of the food was increased, the researchers found that the foods broke apart differently when chewed, which exposed more surface area and increased the saltiness.

"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," Lee explained.

Making food more porous could also improve frying process, reduce oil uptake

Lee's colleague, Pawan Takhar, believes that this approach may yield strategies to optimize the frying process, reduce oil uptake and produce lower-fat foods:

"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, vapors 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."

Researchers have previously investigated capillary pressure in the oil - the force that makes overall pore pressure negative.

"The trick is to stop when pore pressure is still positive (or less negative)," Takhar reports, "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."

The Illinois researchers - who are both experts in food engineering and professors in the College of Agricultural, Consumer and Environmental Sciences' Department of Food Science and Human Nutrition - believe that when this balance is achieved, it will result in lower-fat healthier fried foods.

So far, Lee and Takhar have published two studies based on their ongoing research - in the Journal of Food Science and Food Research International - which is funded by the US Department of Agriculture.