University of Saskatchewan researchers pioneer radio frequency method to make legumes easier to digest

Researchers at the University of Saskatchewan have developed a new way to make legumes like beans and peas more digestible, using radio frequency heating to reduce antinutrients that can interfere with human and animal digestion.

Legumes, though a dietary staple for centuries, naturally contain compounds such as tannins, lectins, trypsin inhibitors, and phytic acid, which help protect the seeds from pests but also make them harder to digest. Traditionally, food processors heat legumes in large ovens to break down these compounds. However, these ovens are inefficient and can scorch the outer layer of the legumes before the interior reaches the necessary temperatures.

A team in USask’s Department of Chemical and Biological Engineering has found that radio frequency, or RF, heating offers a more precise and energy-efficient solution. The method works similarly to how microwaves heat water inside food, said Tolen Moirangthem, a PhD student on the project. “When you put a cup of water in the microwave, the water heats up, but the cup doesn’t. The same is true for the pea—the water inside heats up, but the rest of the pea doesn’t.”

This “selective heating” allows the team to preserve desirable nutritional qualities while deactivating antinutrients more quickly. Unlike conventional methods that can take hours, RF heating requires only a few minutes.

The researchers hypothesized that as water inside the legumes turns to steam during RF heating, it creates pressure that bursts pores open in the seeds. Tests at the Canadian Light Source confirmed this effect, showing that RF-treated beans developed more and larger pores.

Importantly, the process reduced trypsin inhibitors, a type of antinutrient protein, by 81%. Moirangthem said the findings could help address global food security challenges. “We know that we have big potential with this project,” he said. “Animal protein is very expensive in different parts of the world, so we need sustainable plant protein that can be produced at mass volume to feed the world population.”

Beyond nutritional benefits, the RF heating technique could also lower energy use in processing legumes, making crops like beans and peas even more environmentally sustainable.

(Main photo courtesy of Canadian Light Source)