Pumped-up super veggies show their nutritional colours

Scientists around the globe are developing fruits and vegetables with boosted nutrient contents in a rainbow of unusual colours. Shane Starling sinks his teeth into a world of orange cauliflower and purple carrots

Given their inherently nutritious composition, most fruit and vegetable breeding programmes have tended to focus on improving aspects like appearance, taste, texture, shape and shelf-life. But more and more research energy is now being channelled into making fruits and vegetables even healthier.

From corporate seed developers through growers to academic researchers, enhancement of fruits and vegetables is continuing at such a pace in many parts of the world that commercial results are beginning to see the light of day. Consumers can now pick from purple carrots and tomatoes in the US to protein-rich potatoes in India to orange cauliflower in the UK.

The Vegetable & Fruit Improvement Center (VFIC) at Texas A&M University is a leading research hub in the area and created one of the world?s first ?super vegetables? about a decade ago—a purple carrot breed that had 40 per cent more beta-carotene than usual. The carrot, named BetaSweet, and now available throughout the US, was also bred to have a higher sugar content to improve flavour, as well as a crispy texture to make it more palatable for children. Other breeding programmes had taken place with regular carrots and they too had their nutritional profiles improved, but they lacked the unique marketing appeal of a carrot that wasn?t orange.

?If you develop something new that is truly significantly better for nutrition and health, you must be able to identify it,? says Leonard M Pike, PhD, research leader at the VFIC. ?It?s got to be carried through to the consumer. Once we develop these varieties, we must have a way to get the consumer to know what they are. That?s what this is about—breeding for nutrition and for the grower, shipper, trucker, chemical producer and retailer. The maroon colour is perfect for identifying and promoting the BetaSweet variety.?

Other work being conducted at the VFIC and its partner institutions include:

  • developing the anti-carcinogen properties of citrus fruits.
  • increasing the carotenoid content of watermelons and cantaloupes.
  • developing milder and sweeter onions with increased quercetin and anthocyanin levels.
  • increasing the quercetin levels of peppers and making them sweeter.
  • increasing anthocyanin levels in stone fruits.
  • developing lycopene-enriched tomatoes.

Associate professor Stephen R King, a researcher principally involved in the watermelon and cantaloupe programme, says most research at the VFIC is done using selective breeding principles.

Genetic-modification techniques, while not widely practised, are not totally conspicuous by their absence.

?We don?t do much GM,? he notes. ?That said, a researcher at one of our associated institutes has located genes that increase calcium in carrots, tomatoes and potatoes. He?s been getting some great results. He?s solving problems caused by calcium deficiency, such as blossoming end-rot in tomatoes and storage problems for potatoes. So he?s improving the nutritional profile of the product while also having a producer benefit. It keeps the vegetable healthy as well as being a healthier vegetable.? Despite such exciting GM-based work, the VFIC will remain focused on more natural methods in the short- to medium-term. ?Natural variation is already there in many cases, and it is just a matter of selecting for it. GM is not necessarily better,? King observes.

As its name suggests, the VFIC is principally concerned with fruit and vegetable research and improvement, but it also vigorously pursues links in the clinical sphere.

?In terms of efficacy, it?s important we connect with medical researchers to discover if the nutrient levels we develop are of any benefit to people,? King said. ?We might get a doubling or tripling of a compound, but the levels might be so low to start with that the end amount is insignificant. Potato is a good example. There are carotenoids and flavonoids in potatoes but they are at very low levels. But the consumption of potatoes is significant enough that these lower levels of nutrient presence can be significant.?

Potatoes are in fact the world?s most commonly consumed vegetable, although their consumption has been falling in some Western markets due to the effect of low-carbohydrate diets. Perhaps, with this in mind, Indian researchers using GM techniques have developed a high-protein potato that is being rushed to market to cash in on the low-carbohydrate diet craze.

Tomatoes rank next in the vegetable popularity league, with each US citizen consuming about 90 pounds of tomatoes in 2003. Recent work has focused on breeding programmes aimed at increasing their now-prominently marketed lycopene levels. Much of it has been successful. A programme at Oregon State University with a different bent has bred purple tomatoes with boosted anthocyanin content that could have tomatoes competing with the likes of blueberries and grapes both as functional foods and extracts and even as polyphenol supplements.

?We are learning about how anthocyanin genes are expressed in tomatoes and how we might cross tomatoes to get more nutritional value,? says Jim Myers, a professor of vegetable breeding. ?The medical, the nutritional and the food research industries all are keenly interested in the health benefits of phytochemicals in all sorts of fruits and vegetables. We are happy to find out we can accomplish this in tomatoes using traditional, classical plant-breeding techniques.?

This accent on health has seen seed growers like California-based Seminis alter its product development criteria. The company recently launched a broccoli variety high in glucosinolates—a naturally occurring cancer-fighter. ?In addition to our traditional focus on grower requirements, we have geared our research toward consumer needs and preferences,? president Eugenio Najera says, ?in this case providing nutritious vegetables with enhanced health benefits.?

Of course, this activity would not be occurring if demand weren?t there, according to Stuart Cox, technical manager at the UK division of Japanese multinational seed developer Sakata Seeds. ?The seed industry is looking further down the food chain to what consumers really want, and they want health. The functional elements are now key breeding objectives. The supermarkets do the consumer surveys and they are coming to us and asking for these new varieties, so the public demand is clearly there. And if they are visually identifiable as being extra-healthy, people will pay for that too.?

UK-based grower Staples Vegetables has found success in varieties that have unique colour and health properties, such as red, green and orange cauliflowers with boosted anthocyanin levels. Managing director Vernon Read points out that the potential for transference of colours between vegetable varieties is almost limitless and that growers are realising the benefits of carrying such new hybrids. ?If there is a demand for them we will be interested in them because they can set us apart from our competitors,? he states. ?This is particularly true when cheaper produce is often readily available from other growers in locations often thousands of miles away.?

Sales of the cauliflower varieties have been increasing steadily, even if many consumers are not immediately aware of the nutritional aspect of the produce. ?Although it?s the colour that attracts people in the first place, once we have their attention, we inform them of the health benefits,? Read observes. ?I think there?ll be more colour in the future. There?ll be the appeal of the product visually, and there?ll be the health benefit.?

So an apple a day—or perhaps a purple carrot or red cauliflower—may keep the doctor away for years to come.

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