Reducing Discomfort Related to Eating Pulses
April 25, 2017
Researchers look for strategies to reduce raffinose family oligosaccharide concentration in lentils and chickpeas
Raffinose family oligosaccharides (RFO), a group of soluble sugars including stachyose and verbascose, have beneficial effects on humans, but can also present some undesirable effects.
“Humans lack the raffinose family oligosaccharide-digesting enzyme, alpha galactosidase,” explains Dr. Ravi Chibbar, Professor and Canada Research Chair in Molecular Biology for Crop Quality at the University of Saskatchewan. “As a result, raffinose family oligosaccharides pass undigested into the lower gut, where they are fermented by bacteria.”
The result is gas, and in extreme cases, diarrhea. It is easy to see why this can become a barrier to increased pulse consumption, even though they provide a good balance of proteins and carbohydrates and contain many essential vitamins and minerals. They also contain non-starch complex carbohydrates, which are the major components of dietary fibre for which pulses are celebrated and consumed.
“Half to two-thirds of a pulse seed’s dry weight consists of carbohydrates, one of the most versatile storage components affecting both the extrinsic and intrinsic seed quality,” Chibbar says. “Starch is the predominant storage carbohydrate and the major contributor to seed weight and grain yield.”
“In comparison to cereal starch, the amylose concentration in pulse seed starch is significantly higher,” he continues. “This is a positive factor for human health, especially as a preventive measure to reduce the incidence of Type 2 diabetes and cardiovascular diseases.”
To increase pulse consumption in the human diet, seed composition needs to be tailored to meet consumer needs. That means reducing RFO concentration in pulses to decrease the incidence of discomfort experienced after they are consumed.
To this end, Chibbar led a research project that was funded by Saskatchewan Pulse Growers, focusing on developing strategies to reduce RFO concentration in lentils and chickpeas. During the last five years, he and his research team characterized chickpea and lentil germplasm collections for natural variation in seed carbohydrates, especially soluble sugars such as RFO, and identified genotypes with very high and low RFO concentrations.
“The characterized genotypes are a valuable genetic resource to develop chickpea and lentil varieties with desired carbohydrate profiles to meet consumer demands,” he says. Understanding of the biochemical and genetic basis of RFO accumulation in chickpea and lentil seeds has resulted in identification of target genes regulating RFO and how they accumulate in seeds.
“The identified DNA markers, when completely characterized, will accelerate development of lentil and chickpea varieties with reduced raffinose family oligosaccharides, thus causing less stomach discomfort,” Chibbar says. “This will further promote consumption of lentil and chickpea or their products.”
This is good news for Saskatchewan pulse growers who are well suited to fill new market demand created by increased human consumption.
The DNA-based markers identified in this project can also be used for other pulse crops, such as pea and beans, and reduce the time needed to respond to changing market demands.
SPG Investment: $281,760
Project Length: 5 years
Co-Funder: Natural Sciences and Engineering Research Council of Canada - $251,550
Project Lead: Dr. Ravi Chibbar - Professor and Canada Research Chair in Molecular Biology for Crop Quality, University of Saskatchewan