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Antioxidants give potatoes a market edge

Alberta research scientist believes overall lutein content could provide incentive for price premium

Dr. Michele Konschuh

When carb-conscious eaters shied away from potatoes during the popularity of the Atkins diet, researchers at the Alberta Agriculture research station in Brooks, Alta., began looking for reasons to eat the humble spud.

Sure, potatoes may be loaded with carbohydrates, but they’re also packed with vitamins and some even boast antioxidants, a group of compounds that have boosted the fortunes of blueberries, dark chocolate and red wine.

One of the most promising of the antioxidants in potatoes, in the eyes of Dr. Michele Konschuh, a research scientist with Alberta Agriculture, Food and Rural Development, is lutein.

Known to help slow the onset of age-related macular degeneration, a disease that strikes one in three Canadians over the age of 55 and 40 per cent of those aged 75 and older, lutein acts like sunglasses on the inside of the eye. Just three to six milligrams of lutein a day can help prevent the damage that leads to the clouding of the eyes that characterizes the disease.

The average multivitamin delivers 600 micrograms of lutein a pop, while the results of a six-year study released by National Eye Institute researchers in September 2007 identified leafy greens such as broccoli, collard greens and kale as good sources of lutein.

Since the advantages of lutein are well documented, and yellow-fleshed varieties of potatoes were known to be high in antioxidants including lutein (whose name comes from the Latin word for “yellow”), Dr. Konschuh wanted to determine if the levels were high enough to support any particular claims for potatoes.

“We’re not really trying to compete with leafy green vegetables,” Dr. Konschuh told growers at the annual conference of the British Columbia Potato and Vegetable Growers’ Association, held last November.

Dr. Konschuh’s work began in 2004.

Seed companies suggested varieties for use in the study based on market potential in Alberta. A selection of five fresh market varieties and five processing varieties were chosen, including Agata, Cecile, Innovator, Island Sunshine, Piccolo, Sante, Satina, Sinora, Victoria and Yukon Gold.

Tubers of each of the varieties were grown at three sites in 2005 and tested for lutein stability and availability. The variety Agria took the place of Sante in a 2006 trial.

The running average across varieties after cooking was a yield of 60 micrograms of lutein per 100 grams of fresh weight, though Agria checked in with upwards of 86 micrograms. Satina was most consistent in delivering a high level of lutein in trials.

Based on an average serving size estimated at 175 grams, it was determined that a helping of potatoes could contribute a significant portion of the daily allowance of lutein.

Better, it appeared that with some varieties, cooking boosted lutein measurements, suggesting that it became more available after cooking.

“You’re not losing all the lutein by processing potatoes,” Dr. Konschuh said.

And, since the body absorbs lutein better with fat, Dr. Konschuh told growers mashed potatoes with butter (in moderation, of course) can actually be good for those looking for a dose of lutein.

The results were sufficient to support a claim of “contains lutein” on packaging.

The next step, in 2006, was to determine approximate lutein content for labelling purposes.

“Lutein concentration is definitely variety dependent,” Dr. Konschuh found.

The second year of research found that potatoes with flesh of a deeper yellow may have greater lutein content, as may smaller tubers or those that have experienced stress while growing.

Discussing the concentration of lutein in the potatoes with marketing consultants, Dr. Konschuh’s team was told the levels of lutein were sufficient to distinguish potatoes on the market. Rather than having to compete on price alone, the potatoes offered something significant enough to consumers that they might be willing to pay a premium for it.

“We realized we may not have to compete on price point,” Dr. Konschuh said.

While the initial trials are over, Dr. Konschuh said future directions for research could include testing new
varieties for lutein content as well as developing agronomic information that will help growers produce lutein-rich
potatoes on an informed, commercial basis.

But the participation of industry will be vital to these endeavours, because the research will only be of importance if the industry is willing to tout the benefits of lutein as a marketing point, creating a market for the vegetables.
“Anything further that we do on this really has to be led by industry,” Dr. Konschuh said.