It’s a bit like a high-tech playdough machine.
But instead of pliable, multi-coloured dough, the extruder at the University of Manitoba uses pulses or cereals as base ingredients. And instead of a string of dough forced through molds to create basic shapes, the result is value-added food products.
Researchers hope their work will lead to a more efficient and sustainable food system with a diverse range of foods that incorporate grains and create a larger market for byproducts.
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Extrusion processing has been used in the food industry since the 1940s or ‘50s, notably for creation of products like puff snacks and Cheerios.
“In the context of extruded foods, we study anything from pop snacks and breakfast cereals to meat extenders and meat analogues,” said Filiz Koksel, associate professor in the university’s department of food and human nutritional sciences.
Koksel was one of the presenters at the Food Technology and Research Day Nov. 1 at the Richardson Centre for Food Technology and Research in Winnipeg.
Put simply, extrusion involves a specialized machine that mixes ingredients (usually both solid crop-based ingredients and liquids like water or oil) and pushes them through a small opening and down a barrel under various pressures and temperatures.
“We start with cereals, legumes or different oilseeds in powder form,” Koksel said. “We add that into the extruder barrel; we add our liquids and then we blend, cook, shape and cut these ingredients to make extruded food products.”
For puff snacks and cereals, shaping and cutting is key. For other products, it’s about changing some trait within the base ingredient.
For example, Koksel said, researchers might process wheat flour through the extruder to see if the flour’s functional properties, like water binding capacity, can be altered during mixing and baking. That modified flour would then be tested in an end product like bread.
New plant proteins
Meat alternatives are another area of interest, and the university has an edge. It has the only provincially certified food-grade facility for production of plant-based meat alternatives.
“The idea is to transform plant proteins into structures that can mimic the structure of animal meat, for example roast beef or chicken,” Koksel said.
To do that, the team manipulates the conditions of extrusion, thus affecting properties like hardness and colour in the final product.
One of the challenges is mimicking the ‘mouth feel’ of meat, a catch-all term for factors like the substance’s firmness or chewiness.
Koksel’s team found they could affect the mouth feel of a product by using flowing agents during extrusion to create bubbles.
“These bubbles stay inside the extruded food product and contribute to the texture,” Koksel said. “We’re finding that these foods with additional bubbles in them are softer in texture. It gives us another avenue for manipulating the texture properties of plant-based meat alternatives.”
The process for making meat alternatives requires high-moisture extrusion cooking and usually uses soybean protein, although Koksel’s team is pushing that barrier. The team is also trying underutilized commodities like flaxseed meal, faba bean and lupin protein, as well as industry co-products like spent grains from breweries and cold-pressed sunflower meal.
That last option still needs fine-tuning, Koksel said. Results from the more novel crops have been mixed.
Faba beans have given good results, but “the pea proteins that we’re currently using may need a little bit more innovation.”
The far less popular lupin shows promise.
“So far, what we’re seeing is that it is texturizing very well compared to the rest of the underutilized ingredients in the sector,” Koksel said.
The legume hasn’t taken off as a grain crop in Manitoba, although field testing has been done.
