Same taste, less fat – Oleogels may be the answer to healthier fried foods

Why is deep-fried food so delicious? Is it the crunch of a crispy coating? The salty, tenderizing marinades? Or is it the fact that humans have programmed by years of evolution to love high-calorie dense foods?

Often soaked in salty brine and buttermilk, then deep-fried in oil, traditional fried chicken is a taste treat with a high health price. High in both saturated and trans-fats, it joins the list of deep-fat fried foods that put consumers at risk for coronary artery diseases, heart attacks and stroke.

The food industry has long sought a new frying medium that could offer the taste and texture of traditional oils, but without the dietary drawbacks of a high-fat diet.

Reza Tahergorabi, Ph.D., associate professor of food and nutritional sciences, has taken on the challenge of finding a deep-frying medium that can reduce fat uptake of the food itself – namely, fried chicken – without generating trans-fatty acids.

“I’ve been asked by many researchers, ‘Why do you want to reduce fats in deep-fat fried foods?’ ” said Tahergorabi. “Fat, to a certain extent, is beneficial for us. Fat constitutes a fundamental element of the diet. It’s appreciated for its flavor, palatability, texture, and aroma. It serves as a source of energy and aids in the transportation of fat-soluble vitamins such as A, D, E, and K within our bodies.

“Fats also offer protection by acting as padding and insulation. A significant portion of our brain is composed of fat. So, there are numerous advantages to incorporating fats into our diet. However, the concern arises due to the excessive consumption of fats, particularly in the U.S., which contributes to a range of non-communicable diseases such as cardiovascular disease, diabetes, as well as weight gain and obesity.”

According to statistics from the Center for Disease Control and Prevention, surveys conducted between 2017 and 2020 show that 41% of Americans suffer from obesity, while a 2019 study from the Mayo Clinic reported that as many as 1 in 3 Americans eat fast food – much of it fried -every day.

“Of course, diet is just one factor,” said Tahergorabi. “Obesity, cardiovascular disease, and diabetes are caused by multiple factors that also include lifestyle and genetics. But we are nonetheless trying to address these concerns.”

The choice of frying oil and its composition significantly impacts the absorption of oil in deep-fat fried foods. Different oils possess distinct chemical properties, including fatty acid composition and smoke point, which play a role in their interaction with food during the frying process. While hydrogenated oils, lard, beef tallow, and shortening were once favored by many eateries for their flavor and texture, their usage has declined due to health concerns associated with trans and saturated fats. Comparatively healthier mediums with unsaturated fat, such as canola oil, peanut oil, and corn oil, have become the standard for frying. But, Tahergorabi said, these still come with challenges of their own.

“The shelf life of these types of oils is shorter because they contain a higher amount of unsaturated fatty acids,” said Tahergorabi. “As a result, the oil needs to be constantly changed in the vat when frying. Additionally, the unsaturated fatty acids also give you a greasy texture when eating.”

Posed with two different types of frying mediums that each contained strengths and weaknesses, Tahergorabi and his team turned to oleogelation, the process of converting liquid vegetable oil into a solid-like gel, in order to combine the two mediums and achieve a healthier result: a semi-solid structure that can salvage the taste and sensory properties of the fried food without generating trans and saturated fats. The concept of using this “oleogel” as a frying medium, the professor said, found its inspiration from its use in the pharmaceutical industry.

“The pharmaceutical industry uses oleogelation in ointment, cream and they use the oleogel a delivery agent for medicine,” said Tahergorabi. “Let’s say the product has bioactive compounds and it needs a delivery agent. The oleogel makes it faster to deliver the medicine to the patient and can improve the stability of that bioactive compound. We got that idea and asked, ‘What if we can use this oleogel in foods?’”

Development of the project began in 2020, funded through a $500,000 Evans-Allen grant. According to Tahergorabi, while previous studies have tested oleogels’ effects on saturated fat reduction and sensory qualities in chocolate and sausage, his team decided to test its properties in the lesser-explored area of deep frying.

Tahergorabi and his students purchased fresh chicken breast from a local grocery store, cut the poultry into equal bite-size pieces, and prepared the samples in batter and breadcrumbs. He then added accurately weighed carnauba wax – a natural, plant-based wax used in both edible and non-edible products from cosmetics to hard-shelled candies – to canola oil and heated to a melting point higher than 90 degrees Celsius. The dispersion was cooled at an ambient temperature, forming the oleogels as the frying medium.

From there, the battered and breaded chicken breast strips were deep-fried in a commercial fryer at 177.7 degrees Celsius for three to four minutes in both canola oil and the oleogel in measurements of 5% and 10%. The team changed the frying medium after each batch of chicken to avoid the oil’s degradation from affecting the experiment.

According to Tahergorabi’s results, the use of oleogel as a frying medium did not affect the protein or ash content of the samples, but did decrease moisture loss and fat uptake significantly, and the 5% oleogel sample had the lowest thiobarbituric acid reactive substance (TBARS) and puncture force values throughout 8-day storage, meaning less oil broke through the crust of the fried chicken batter.

“We successfully achieved a 9% reduction in fat uptake compared to control samples fried with traditional oil,” said Tahergorabi.

While the results were promising, Tahergorabi said, the team needs to make some sensory evaluations for taste, touch and smell.

“We think that more extensive research and optimizations are needed to understand the practical implications and limitations of the oleogel as a frying medium,” said Tahergorabi. “It’s been used in the pharmaceutical industry, but it’s still in its early stages in the food industry and we are still exploring and discovering all of these aspects in frying to build to a real conclusion and, eventually, commercialization.”

This project, according to Tahergorabi, is not his first exploration into deep-fried foods; in 2017, the professor began a study to develop a protein-based edible coating, derived from proteins isolated from chicken and fish processing by-products, to reduce fat absorption, resulting in a fat uptake reduction of 80% in fried chicken and 60% in fried fish, respectively, without affecting sensory properties. During this process, Tahergorabi’s team also developed a new batter with sweet potato starch to compare with traditional corn starch batter, with the former yielding an even higher fat uptake reduction than the latter, as well as studied the fat uptake changes and consequent physicochemical changes in deep-fat fried chicken products over a period of frozen storage.

With the oleogel experiment closing this fall, Tahergorabi said a new project, aimed at simultaneously reducing fat-uptake and toxic compound formation in deep-fried meat products, is currently underway.