Cooking with Colour, Pigmented Potato Spud Smart Spring 2011

For thousands of years, people living in South America’s Andean region, where the potato originated, have eaten pigmented, or coloured-flesh, potatoes of the Solanum species. These blue, purple, red and yellow varieties, which come in many different shapes and sizes, are considered the norm for potatoes by South Americans. Europeans and North Americans are used to growing and eating primarily round and oval varieties with white- and cream-coloured flesh. But it might not be too long before Canadian consumers start seeking out pigmented varieties upon learning about the additional health benefits they provide.

CookingWithColour1The deep blue colouring of blueberries, purple of blackberries and red of beets indicate these foods are good sources of antioxidants. The antioxidants found in these foods, such as anthocyanins and phenolics, are also present in pigmented potatoes and, according to research results, in comparable amounts. Antioxidants are thought to slow the degradation of cells in humans and play a role in preventing heart and blood diseases as well as some forms of cancer.

Published last year, a study supported by the Washington State Potato Commission and U.S. Potato Board titled, Pigmented Potato Consumption Alters Oxidative Stress and Inflammatory Damage in Men, shows how eating pigmented potatoes on a regular basis is linked to a reduction in inflammation and DNA damage in the study’s male subjects. Three groups of men between 18 and 40 years of age were fed 150 grams of cooked white-, yellow- or purple-fleshed potatoes every day for eight weeks. Analysis of their blood for antioxidant capacity revealed that the men who ate the yellow- and purple-fleshed potatoes showed lower oxidative damage and inflammatory cytokine concentrations, which have been linked to chronic disease development. Members of the study who ate the purple-fleshed potatoes had the lowest level of this biomarker.

Canadian Researchers Testing Benefits

Canadian researchers have had similar findings in studies on disease and nutrition in humans. Helen Tai, a research scientist with Agriculture and Agri-Food Canada’s Potato Research Centre in Fredericton, and co-lead of the BioPotato Network, says the results of the American study are interesting and supportive of the research being done on potatoes in Canada. “I thought that it was very encouraging,” she says. “Researchers in the BioPotato Network have also found beneficial bioactives for human health in potatoes.”

At AAFC’s Lethbridge Research Centre, Qin Chen, a potato molecular cytogentic research scientist, is also working to identify the antioxidant content of various potato varieties and the effect of potato antioxidants on the proliferation of cancer cells. He found that all potatoes contain a good level of antioxidants; however, the pigmented varieties contain higher levels than paler-fleshed varieties common to commercial production in Canada. The proliferation of colon cancer and liver cancer cells was significantly inhibited by potato antioxidant extracts. The highest anti-proliferative activity was observed in extracts of Solanum pinnatisectum, a Mexican wild potato species showing the highest antioxidant content and bioactivities. At the present time, Chen and his research group are working on transferring the high-antioxidant-producing genes of S. pinnatisectum into pigmented potatoes. “Not only do these pigmented varieties provide food, but they also have more health benefits,” he says.

Purple Mash with Turkey

CookingWithColour2Researchers with the BioPotato Network are also experimenting with cooking methods to determine which will best preserve the antioxidants in pigmented potatoes. Not surprisingly, boiling releases the pigment. “When you boil them, you see [the pigment] leaching into the water,” says Tai. Steaming minimizes pigment loss, as does cooking the potatoes with their skin on.

The best preservation method seems to be dehydration to produce potato granules. “The cell structure is maintained and we are able to conserve anthocyanins,” says Tai. Microwaving also allows pigmented potatoes to retain their nutritional benefits.

A blue or purple potato in the grocery’s produce section may be a rare sight in Canada now, but that is about to change. One of Edmonton’s Little Potato Company’s selections called the Terrific Trio contains red-, yellow- and blue-fleshed creamers. The company’s marketing assistant, Melanie Kremp, says the main blue-fleshed variety they use is called Russian Blue, and is custom-grown by a producer near Edmonton. In the off season, they partner with growers in the United States to ensure the blue potato is available year round.

The Terrific Trio potatoes are creamers ranging in size from three-quarters to one and five-eighths of an inch in diameter. They are meant to be cooked with the tender skin on, so the full nutritional value of each variety is consumed.

Scientists at the Potato Research Centre have collaborated with chefs at Holland College’s Smartest Kitchen in Charlottetown to see how pigmented varieties cook up and how the granules can be used to boost the nutritional value of other foods. “The dried granules have been used to make delicious potato croquettes, but the chefs are also working on ways to incorporate them as an additive for extra nutrition in processed seafood products,” says Tai.

Introducing New Varieties

CookingWithColour3In 2007, the first pigmented selection was included in AAFC’s Accelerated Release Program, which was designed to introduce new potato selections to Canadian potato producers. According to program guidelines, this year another pigmented selection, AR2009-10, along with the other 2009 selections, will be open for cash bids, giving industry participants the chance to exclusively test a selection for up to three years. Agnes Murphy, research scientist with the Potato Research Centre, says it will be interesting to see if anyone wants to bid on the pigmented selection that is now available.

There are two new pigmented varieties in the 2011 selections: a purple-fleshed variety in the french fry class and a red-fleshed variety in the fresh market class.

These pigmented selections have been developed for growth and processing in Canada. Many of the native Andean pigmented varieties would not grow well this far north because of the different soil conditions and day-length requirements. As well, some varieties yield fewer and smaller tubers than modern commercial varieties. Their deep eyes and irregular shapes also make processing and bulk handling difficult.

Calla Farn, vice-president of Government/Public Relations and Corporate Affairs at McCain Foods (Canada), the country’s largest potato processor for french fries, says the company has tested many different flesh-coloured varieties in research trials. Farn says, like all potatoes, pigmented varieties are nutritional powerhouses but recognizes that these varieties pack even more of a punch.

Consumer Demand Needed

Peter VanderZaag, owner of Sunrise Potato Storage Ltd. in Alliston, Ont., has grown potatoes for decades, and he’s travelled around the world to help others increase domestic potato production to feed hungry people. As board chair of the International Potato Center, he is well aware of the traditional Andean pigmented varieties, and the nutritional value they and other pigmented potatoes possess.

On his own farm, he mainly grows potatoes for chip production, but he has crossed pigmented with non-pigmented varieties. While some potato chip makers, such as U.S.-based Terra Foods and Frito-Lay’s South American plants, use pigmented potatoes to add variety, colour and extra nutrition to their products, the major Canadian chip makers aren’t yet buying pigmented potatoes.

It’s the current lack of consumer demand that stops P.E.I. private breeder Joyce Coffin from registering the yellow-, red- and blue-fleshed seedlings she’s breeding. She’s aware of the food testing underway at Holland College and thinks consumer acceptance might happen one day. “Let’s just see if the market comes alive,” she says.

Consumer demand will come from education on the added benefits to be gained from eating pigmented potatoes, speculates VanderZaag. “I think that it won’t happen overnight, but it will happen,” he says.

Tai says Canadians eat an annual average of two kilograms of blueberries compared with an average of 30 kilograms of potatoes. In the future, pigmented potatoes may become an alternative source of antioxidants for Canadians once consumers are aware of these varieties and their nutritional value.

Pigmented varieties may offer potato producers new ways of attracting consumers and increasing potato consumption. As well as educating consumers about the nutritional merits of pigmented potatoes, Tai says there may be another way to use their nutritional content-in livestock feed. By adding compounds taken from pigmented potatoes to feed for cattle and poultry, the use of antibiotics and other nutritional supplements could be reduced. “Those are some areas we are now exploring,” she says.

Applying modern scientific technology to one of the world’s most ancient crops could lead to the development of an economical source of natural nutrition for Canadians.

Andrea Geary