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Exploring ways to increase pulse consumption

Pulses, such as beans, peas, chickpeas and lentils, have a lot going for them. They are good for you, they taste good and they help improve the sustainability of agriculture. But some people avoid eating pulses because they worry about bloating and gas. Now a three-year project is exploring ways to deal with that barrier to pulse consumption.

“Some of the carbohydrates in pulses are not digested by the enzymes we have in our gastrointestinal tract. It’s mostly indigestible polysaccharides that are responsible. When you eat pulses, [these indigestible components] stay in the lower GI tract and get fermented. The fermentation results in the production of gas, which causes bloating and that feeling of discomfort,” explains Dr. Joyce Boye, the Agriculture and Agri-Food Canada (AAFC) research scientist who is leading this project.

According to Boye, a lot of people, especially in North America, don’t consume as many pulses as would be good for them because of the feeling of discomfort they get. “So the question was: are there things that could be done to help improve the digestibility of the pulses?”

To answer that question, Boye and her research team are investigating the possibility of adding enzymes and probiotics during pulse processing to help break down some of these indigestible polysaccharides, either before people consume the pulses or earlier on in the gastrointestinal tract.

The project is being conducted at AAFC’s Food Research and Development Centre in Saint-Hyacinthe, Quebec. The research team includes Dr. Claude Champagne, Dr. Byong Lee (retired) and Dr. Andy Szilagy, and post-doctoral fellows Dr. Elham Azarpazhooh, Dr. Archana Kumari and Dr. Sung Hoon Park. Project funding is through Growing Forward’s Pulse Science Cluster research initiative, AAFC, Bonduelle (a vegetable and fruit company), Manitoba Pulse Growers Association and Pulse Canada.

This particular project is targeting dried beans that are processed into frozen products. For many consumers, a frozen pulse product would be more convenient than dried pulses, which require cleaning, soaking and cooking.

“This research is important to Canada’s pulse industry because it develops the technology and knowledge base that will lead to new pulse product options for consumers who are looking for nutrition, flavour and convenience. The project addresses many technical issues and barriers to pulse consumption including preparation, digestibility, flavour and shelf stability issues,” says Tanya Der, manager of food innovation and marketing at Pulse Canada.

“Currently, commercial availability of frozen pulses is limited, and so we are excited about the project results and hope to see more pulses in the freezers of grocery stores and foodservice operations in the near future.”

Enzymes and probiotics are already used by some consumers who have trouble digesting certain foods. “You may be familiar with products such as Beano, which is an enzyme that people can take as a tablet before or after they consume legumes. The enzymes help break down the carbohydrates,” notes Boye. Probiotics are beneficial microbes that people can consume in foods or as supplements. In the case of pulses, the indigestible polysaccharides become the food for the probiotics.

For frozen beans, the researchers need to find probiotics and enzymes that function together effectively after the product has been partially cooked and then frozen at the processing plant, and during consumption.

“The project involves understanding, first of all, what is happening at different stages of processing, how these different micro-organisms and enzymes respond to different processing conditions,” says Boye.

“At this point, we are looking at the different processes to ensure that the probiotics we select and the enzymatic activity are compatible. We have information on the ways in which they respond to different treatments, and based on that information we will be able to select specific ones for clinical trials, which we hope to do in the coming months.”

The researchers have already identified some promising probiotics and enzymes, and are currently doing digestion tests in the lab to assess the effects on indigestible carbohydrates. Those tests will help determine which probiotics and enzymes to move into clinical trials. Clinical trials are very important because what happens in a test tube isn’t always directly transferable to what happens in a living body.

“I’m cautiously optimistic that we’ll be able to find a way to reduce the discomfort associated with the consumption of beans. It’s going to be through judicious selection of the right combination of treatment versus micro-organism-enzyme activity,” states Boye.

By developing convenient pulse products that cause less discomfort, this project could contribute to increased pulse consumption, especially in North America. Increased pulse consumption offers benefits for human health and the environment, as well as improved markets for pulse growers.

Boye explains that pulses are high in protein, fibre, vitamins and minerals, and low in fat. She adds, “An increasing amount of research is showing that the components in pulses can help reduce the risks associated with a variety of diseases.” For instance, studies indicate that pulse consumption may reduce the risk of such health problems as cancer, diabetes, cardiovascular disease and osteoporosis.

From an environmental perspective, pulses provide various benefits. For example, pulses and other legumes fix nitrogen, so they reduce fertilizer needs, lowering non-renewable energy inputs into the cropping system. Also, adding legumes to diversify a crop rotation can help break disease, weed and insect pest cycles. And legumes have a positive effect on the soil organism community, which can help improve crop production.

Along with this project, other developments in pulse processing could also contribute to increased pulse consumption, notes Boye. “Hopefully, people will increasingly have opportunities to include pulses in their diet as techniques are developed to increase the convenience of use. Some companies are exploring the production of things like flours, starches and protein extracts from pulses that can be used as ingredients in food formulation. I anticipate that, as more and more manufacturers use these ingredients in foods, there would be increasing consumption of pulses in the diet and, as a consequence, health benefits to consumers.”


November 22, 2012
By Carolyn King

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Red kidney beans undergo various processing and cooking treatments that influence how well added probiotics and enzymes are able to improve bean digestibility. Pulses