This article appeared in the Summer 2015 issue of Pulse Crop News.

Researchers at the AAFC Lethbridge Research Centre are canning beans to find out what makes beans from some fields – and even some from within that field – better for canning than others.

“Some bean cultivars are more prone to developing hard seeds, which is highly affected by the environment,” said AAFC Research Scientist Parthiba Balasubramanian, who works on this issue with Research Technician Gerald Kereliuk. “The objective now is to identify lines with no hard seeds. We also look at the canning quality of the lines and how consistently it performed.”

The Lethbridge researchers began looking at these issues for the whole of Canada in 2011, and they received funding from the federal Pulse Cluster 2 program, as well as APG and other grower groups to continue until 2018.

“If it’s predominantly genetically controlled then we can breed to remove that trait,” Balasubramanian noted. “It could happen in the field during maturation of the seed or it could be during seed storage or it could be during the cleaning process. Because we have little control over environmental conditions, the hard seeds are a concern. This concern was brought to us by the industry, primarily by the people who are exporting beans.”

The project overview states that acceptance of dry bean cultivars is dependent on both dry seed (seed size, shape, colour, colour retention and seed coat integrity) and processed seed (canning quality) traits. Percentage of hard-to-cook seed, hydration coefficient after soaking and blanching, washed drain weight, texture, colour, clumping and appearance of seeds after canning are important traits to processors and consumers. A greater understanding of these factors will enable breeders to select genotypes with improved canning quality traits in a breeding program, allow growers to choose cultivars with optimum quality for commercial production in their respective growing environments, and help processors to refine the canning protocol depending on the cultivar.

“The major end uses of dry bean are cooking and canning,” Balasubramanian said. “The (livestock) feed use of dry bean is negligible. The percentage of broken beans that go into feed use is very small. Gerald was instrumental in fine tuning the protocol for cooking to evaluate the lines for hard seed. The first thing we evaluated was the hard seed because one of the problems is when you soak the dry bean seeds overnight, not all of the seeds absorb water, even if they’re from the same seed lot, even within a variety in the same beaker. We see hard seed in other pulse crops as well so it’s a fairly common phenomenon, but it’s poorly understood.”

The bean cultivars and experimental bean lines grown in Alberta, Saskatchewan, Manitoba and Ontario – navy, Great Northern, pinto, cranberry, yellow, black, white kidney, red kidney and dark red kidney – are soaked at room temperature in double de-ionized water for 14- 16 hours, then blanched in hot water for three minutes at 93 degrees Celsius.

“Once they’re blanched, some of the hard seed will pick up water,” Kereliuk said. “There are still some that will never take up water in all of the conditions that we’ve tried, but that is very rare.”

Balasubramanian added: “We just wanted to see if a minor heat treatment would enable these seeds to soak up moisture. Some don’t absorb water so that’s why we go to Step 3, which is the actual cooking.”

The bean seeds are then cooked for 20 minutes at 97 degrees Celsius.

Half of Canada’s bean acres are navy beans, and those are primarily exported to Europe, Balasubramanian noted. The navy beans, canned with tomato sauce, receive a high-pressure steam for 80 minutes at 116 degrees Celsius after the cans are sealed. Other beans are canned in brine.

The Lethbridge facility currently uses a stationary retort that doesn’t shake or move in the canning process, but the facility intends to replace the stationary retort with a state-of-the-art rotary retort similar to what the industry uses for constant motion for better heat distribution during processing. The funding for the new equipment comes from the grower organizations and AAFC.

“Hopefully, that will help us to distinguish a good product from a bad product in terms of canning quality,” Balasubramanian said. “We are fortunate to have an excellent canning facility – it will be state of the art by the end of this year. We are one of the best canning and research facilities in Canada, so that is why we were asked to take on the canning responsibility for the whole country.”

Two to four weeks after the canning process is complete, the cans are opened and the beans are visually inspected for colour and other indicators, Kereliuk explained.

“We like to see whole seeds with minimal amount of cracking,” he said. “A poor cultivar would have cracked and split seeds, and would not get a high rating. Another factor that we look at is matting together or clumping. If the seeds stick together in the can, they won’t flow out very easily and the consumer will have to scrape them out causing some mashing. Some years are worse than others because it’s environmental and the manufacturer has no choice. Severe matting is a rejection right away.”

The researchers also measure drained weight to ensure that the solids in the can amount to 60 per cent by weight of the can’s contents, and texture by using a machine that correlates with chewing.

Balasubramanian said that the prairie provinces and Ontario, which supply bean lines for the trials, have committees that decide which lines should be recommended for registration as cultivars in Canada.

“We look at the canning quality of the lines, and how consistently they performed across the environment,” he added. “All of the experimental lines are compared to the check cultivar that has a large market share.”

What the scientists found is that there are some bean cultivars that are more prone to developing hard seed, which is highly influenced by the environmental conditions. Balasubramanian said that last year in Ontario there was one location that consistently resulted in hard seed for all bean lines grown in that location regardless of market class, but it was just that one year and that single location.

Balasubramanian said that they were unable to pinpoint the reason for the consistent hard seed in the one location last year, but another project recently received approval that will further explore the cause of hard seeds in Ontario-grown navy beans for the Ontario Bean Growers.

Balasubramanian is leading a second sub-activity under the Dry Bean Improvement for Sustainable Production in Canada research project to develop early maturing lines with improved disease resistance. This project’s overview states that dry bean cultivars of six (pinto, great northern, yellow, black, red and pink) bean market classes are grown in rotation with cereal, oilseed, potato, sugar beet and forage crops primarily under irrigation. The days to maturity of dry bean cultivars range from 100 to 105 days in Alberta, which has a short growing season on the prairies.

A major impediment to dry bean production is the lack of early maturing dry bean cultivars with adequate level of resistance to the most prevalent diseases including white mould and common bacterial blight. Development of disease resistant cultivars is one of the most effective and environmentally sustainable methods for reducing yield losses and promoting stable crop production.

White mould is the most important disease constraint for bean growers in Alberta and common bacterial blight is a seed-borne disease.

“We evaluate all of our bean lines for white mould resistance,” Balasubramanian said. “White mould is associated with high moisture and nitrogen. From a breeding standpoint, we’ve identified dry bean lines with better tolerance for white mould.”

In 2014, a pinto bean cultivar called AAC Burdett was registered as a result of the project. Balasubramanian said it is one of the pinto bean cultivars with the best tolerance for white mould, and Viterra has the commercialization rights to it.

He added that through the project, a bacterial blight-resistant black bean line was registered last year as AAC Black Diamond 2 and the research team is in the process of transferring the resistance to other market classes. Currently there are experimental lines in pinto, Great Northern and red bean market classes with resistance to blight.

Balasubramanian added: “It is because of funding from Alberta Pulse Growers, Viterra, Alberta Crop Industry Development Fund, Alberta Innovates – Bio Solutions and AAFC, that we are doing the work that we are doing to grow beans in Alberta.”