Infrared-heated lentils are more nutritious and ‘greener’ to process

“The process makes these macromolecules of starch and protein more accessible to enzymes in our bodies,” Foroushani said.

By tweaking the amount of moisture in the lentils, and the amounts of microwave and infrared energy, the research team was able to make more than 96 per cent of the starch and more than 85 per cent of the digestible protein.

In raw lentils, less than 69 per cent of starch is digestible and less than 80 percent of protein is digestible.

To better understand what happened at the molecular level and examine it in the finest detail possible, the research team analyzed the lentil samples using USask’s Canadian Light Source synchrotron.

USask doctoral student Tahereh Najib and study co-author said starch has a smooth surface.

“We make it kind of rough, so it’s more accessible by enzymes and the starch can be better broken down,” Najib said.

More than two million tonnes of lentils are produced on average each year in Canada, the world’s largest producer, with the majority produced in Saskatchewan. Lentils are harvested, cleaned, and graded before packaging or further processing.

Most are cooked and consumed as a whole grain, but a growing volume of lentils is dried and turned into a powder to isolate proteins from starches and used as a food additive.

USask College of Engineering researcher Dr. Venkatesh Meda is the principal investigator on the study. He said the process takes 200 per cent less drying time.

“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 the release of greenhouse gases,” he said.

In microwaving, heat is generated from the center of the lentil and radiates outward, while moisture and heat escape to the outside environment.

Meda said by simultaneously roasting the surface of the lentils with infrared heat, the research team was able to increase the overall efficiency and better seal in the microwave heat.

“By having more plant-based alternative food ingredients in our diet, one can also reduce our environmental footprint by fulfilling our need for proteins from plant sources,” he said.

The ideal setting of lentil moisture, microwave energy intensity and infrared roasting depends largely on how the lentil flour will be used.

Meda said modified lentil flour can be a great source of plant-based ingredients for dietary and nutritional needs, and kitchen and food processing operations.

“Lentil flour serves as an additive or substitution to our food system to not only make the food nutritious but also preserve its acceptable texture,” Meda said.

The USask-processed lentils have not yet been assessed or approved for official trials involving human or animal consumption, for which a commercial kitchen is required.

The lentil flour tastes good, according to Meda.

“At home we have been using it, and the aroma has improved to ‘acceptable,’ and not deteriorated compared to any other commercial variety,” he added. “We’re happy to report there is not much loss in any of the sensory qualities of colour, texture, and aroma.”

The lentil flour is processed in small batches of 50 grams. The next steps in the research involve improving the flavour, scaling up to process larger amounts of lentils, applying the process to other legumes and oilseeds, and examining whether the technique could also improve seed quality for germination.

The research was funded by the Saskatchewan Ministry of Agriculture and the federal government’s Agriculture Development Fund.

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