Illinois Researchers Develop Hybrid Frying Method to Cut Oil Absorption in French Fries

French fries enjoy widespread popularity due to their taste and crispy texture, yet they absorb substantial amounts of oil during cooking—increasing their fat and calorie content. Excessive consumption of fried foods is associated with elevated health risks, including obesity and high blood pressure.

How microwave energy alters internal pressure dynamics

Researchers at the University of Illinois are investigating whether microwave energy can be used to produce french fries that absorb less oil while preserving flavor and texture. According to Science Daily, findings indicate that combining conventional deep frying with microwave energy may shorten cooking time and reduce oil absorption—all while maintaining a crisp outer crust.

Principal investigator Pawan Singh Takhar, professor of food engineering at the University of Illinois, stated that consumers seek healthier food options, but the flavor imparted by oil in fried foods presents a genuine challenge to reducing fat content.

The physics of oil uptake during frying

The researchers explained that frying involves complex physical changes. At the start of frying, microscopic pores inside the potato are filled with water, limiting oil entry. As temperature rises, water converts to steam and exits the tissue, leaving voids into which oil can penetrate.

Takhar compared this process to a lollipop: when internal pressure within the food is positive, oil remains outside; when internal pressure turns negative, oil is drawn inward. The study found that approximately 90% of the frying period occurs under negative internal pressure inside the potato—creating a suction effect that facilitates oil absorption.

Microwave’s role in shifting pressure balance

Microwave energy heats water inside the potato directly, rather than relying solely on heat transfer from the surface inward. This generates greater steam volume and raises internal pressure—thereby reducing the potato’s capacity to absorb oil.

In laboratory experiments and mathematical modeling of heat and moisture transfer within potatoes during frying, results showed that microwave application accelerates moisture evaporation, shortens cooking duration, and lowers absorbed oil quantity.

However, microwave-only frying proved insufficient to achieve the desired texture: the fries remained relatively soft and failed to develop the customary crispness. The researchers therefore propose a hybrid system that integrates conventional deep frying with microwave energy—where traditional frying forms the crisp outer layer, and microwave energy expedites moisture removal and curbs oil uptake.

The team believes this hybrid approach could enable production of lower-fat french fries that retain consumer-preferred taste and texture, while also cutting cooking time and improving production efficiency. They note that existing industrial fryers used in food manufacturing facilities can be retrofitted with microwave generators—making commercial implementation technically and economically feasible.