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“Zapping” Technique Makes Lentils More Digestible and Nutritious

Red split lentils in a hessian sack.
Credit: Monika Grabkowska/ Unsplash
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Researchers from the University of Saskatchewan have developed a new method of treating red lentils to make the starches and proteins they contain easier to digest. The new process – published in Food Chemistry Advances – also makes producing lentil flour more environmentally friendly.

The power of plants

Lentils are commonly eaten as part of a plant-based diet owing to their high protein and folate content. Although lentils are largely consumed as a whole grain, drying and using them as a powder food additive (as lentil flour) is growing in popularity.

“By having more plant-based alternative food ingredients in our diet, we can reduce our environmental footprint by fulfilling our need for proteins from plant sources,” said Professor Venkatesh Meda, principal investigator at the Department of Chemical and Biological Engineering and lead author of the paper. “Lentil flour serves as an additive or substitution to our food system to not only make the food more nutritious but also preserve its texture,” he explained.

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Less than 69% of the starches and less than 80% of the proteins present are digestible in raw lentils. With the new processing method, more than 96% of the starches and over 85% of the proteins become easily digestible.

“Starch has a smooth surface,” said Dr. Tahereh Najib, a postdoctoral student at the university and co-author of the study. “We make it kind of rough, so it’s more accessible by enzymes and the starch can be better broken down.”

What is the new “zapping” technique?

The novel technique uses a combination of microwave and infrared radiation to generate heat from the center of the lentil, while simultaneously roasting it to seal it from the outside. The researchers were able to combine the two processing techniques in a device that fits on a countertop. The lentil moisture, microwave energy intensity and infrared roasting settings can be modified, depending on how the processed lentils will be consumed.

“Our process takes 200% less drying time,” said Meda, “The unique nature of this energy method is that there is no input of chemicals used for drying and there is no output in terms of release of greenhouse gases.”

Although the processed lentils have not yet been approved for human or animal consumption trials, Meda has been using the lentil flour at home. He reports that “there is not much loss in any of the sensory qualities: colour, texture or aroma.”

Moving forward, the research team is looking to improve the flavor of the lentil flour, then increase the scale of the processing. They also plan to investigate whether the new “zapping” process can be applied to other legumes.

This article is a rework of a press release issued by Saskatchewan University. Material has been edited for length and content.


Reference: Heydari MM, Najib T, Meda V. Investigating starch and protein structure alterations of the processed lentil by microwave-assisted infrared thermal treatment and their correlation with the modified properties. Food Chem Adv. 2022;1:100091. doi: 10.1016/j.focha.2022.100091.