Multicolour Carrots - A Functional Food
Author: P. Muthukumar,
Division of Vegetable Science, IARI, New Delhi-12

Carrot is an economically important cool season root vegetable that has gained popularity in recent decades due to increased awareness of its nutritional value. The root is the primary organ with thick, fleshy taproot that develops from the hypocotyl. Carrots are potential source of dietary nutrients in the form of plant pigments, including carotenoids, anthocyanins, and other flavonoids. China, Russia and United States are the top three producers of carrot globally contributing almost 50% of the world production. India produces 450,518 metric tons of carrots annually from an area of 30,528 ha with 14.7 t/ha productivity (FAO, 2011) and consumed by all strata of the society in various forms such as raw, juice, cooked singly or in combination with other vegetables and as pickle. Tropical carrot is an extensively grown vegetable crop in North Indian plains. It is cherished by one and all, rich and poor for its colour, flavour and taste in various forms like raw, cooked, pickle, candy, puddle, juice, etc. Traditionally, red carrots are popularly grown for commerce by the farmers. In India, two type of carrots are commercially cultivated viz., European carrot (orange colour) are grown in hilly region of the country while, the Asiatic carrots (white, red , purple, multicolour) are grown in a north Indian plains during the winter months (mid August to December). The vitamin A deficiency (VAD) is a major public health problem in India. The highest prevalence of VAD is in parts of Africa and Southeast Asia. Humans cannot synthesize carotenoids and, therefore, must rely on dietary sources to provide sufficient levels. In case of developing countries, where vegetable carotenoids contribute greater than 80% of the available vitamin A. Fruits and vegetables are primary sources of carotenoids in the human diet and their consumption has been associated with numerous health benefits. Carrot root are primary source of β- carotene 600-790 RAE and approximately 88% water, 1% protein, 7% carbohydrate, 0.2% fat, and 3% fiber. There is a wide range of carrot cultivars with various colours, viz., dark red, red, orange, yellow, purple and black which are available to extend the consumer preference as a functional food.

Orange colour carrot

The orange colour of carrot is due to carotenoids. The β-carotene (pro-vitamin A) is a precursor of vitamin A in the human body. Four carotenoids viz., β-carotene, α-carotene, γ-carotene and β-cryptoxanthin have vitamin A activity in humans, which means they can be converted into the visual pigment retinol and are classed as essential nutrients. The predominant carotenoids are the provitamin A carotenes that is α- and β-carotene, accounting for 13% to 40% and 45 to 80% of the carotenoids in orange carrots, respectively. The dietary reference intake (DRI) for vitamin A is expressed as the retinol activity equivalent (RAE), which takes bioavailability into account. The recommended DRI for male and female is 900 RAE, 700 RAE respectively (higher in pregnancy and when lactating), and for children 400–500 RAE. One RAE is equivalent to 1 mg of pure retinol, 2 mg of pure β-carotene dissolved in oil, or 12 mg of β-carotene in food. More than four million children, most of from developing countries, exhibit clinical symptoms of severe vitamin A deficiency, including poor immunity, loss of vision in low light conditions (night blindness) and in extreme cases an irreversible form of blindness called xerophthalmia and maintenance of healthy epithelial cell differentiation, normal reproductive performance, and visual function. The predominant carotenoids are the provitamin A carotenes i.e. α- and β-carotene, accounting for 13% to 40% and 45% to 80% of the carotenoids in orange carrots, respectively. The dark orange varieties have the β-carotene concentration up to 130-500ppm.

Yellow colour carrot

The yellow colour of roots due to xanthophylls (lutein and zeaxanthin) are collectively referred to as a macular pigment (MP). It is found localized in the macular region of the eye in humans and may have importance in eye health and protection from age-related macular degeneration. Lutein is an important pigment in yellow carrots ranges from 1 to 5 ppm. Xanthophyll-rich carrots are associated with a significant reduction in the risk for cataract and for age-related macular degeneration.

Red colour carrot

Red carrots contain lycopene in addition to α- and β-carotene. The utility of red carrot as a functional food depends in part on the bioavailability of its constituent carotenoids. Lycopene is the carotenoid primarily responsible for the colour of red carrots. It is an excellent dietary antioxidant and plays a role in reduce the risk of number of cancers and coronary heart diseases. The lycopene content in carrot varies from 85-100 ppm among the varieties. The red carrots are commonly consumed as a salad and gajar halwa during winter months (November- January) of northern India

Purple colour carrot

A group of polyphenolic pigments called anthocyanins are responsible for the colour of purple carrots. Current cultivars of purple varieties include solid purple carrots, often referred to black carrot. The primary anthocyanins found in purple carrots (sometimes referred to as black carrot), are derivatives of cyanidin, but pelargondin and peonidin glycosides have also been identified. Dietary anthocyanins may play a role in health promotion and protection from cardiovascular disease and anti cancer activity and beneficial effects on diabetes. The total anthocyanins content in carrot ranges from 300 - 350 mg/ 100 g fresh weight in dark purple carrots.

Multi colour carrot

The crossing between uniformly coloured carrot types (e.g. red or orange × yellow or white, purple × yellow) with reciprocal combination gives a wider range of tinge patterns in phloem and xylem (core) of carrots. The types purple carrots with a white core contain very low levels of carotene (4 to 6 ppm), whereas purple–orange carrots (38 to 130 ppm) can contain as much or more total carotene as typical orange carrots. The continued research in carrot cultivar development has produced a novel purple–orange–red cultivar that contains approximately 40 ppm carotenes and 62 ppm lycopene. While these colourful carrots are still a novelty for modern consumers, they share the flavour attributes of their orange counter-parts and are generally well-liked by consumers. Colourful carrots with a variety of pigments have the potential to contribute to the diet, not only the provitamin A carotenes, but also the beneficial health effects of their respective pigments.

Conclusion

Functional foods provide benefits beyond basic nutrition. Biofortified carrots not only provide vitamin A but may contribute to optimal health. The improved genetic background and nutritional profile such as improved flavours and more diverse pigments are of immense importance for the vegetable industry and consumers. The development of novel coloured open pollinated lines, inbred lines and CMS based hybrids boost the tropical carrot cultivation India.

References

Sara A. Arscott and Sherry A.Tanumihardjo 2010. Carrots of many colors provide basic nutrition and bioavailable phytochemicals acting as a functional food. Comprehensive reviews in food science and food safety. Vol 9 pages 223–239.

Simon P, Pollak L, Clevidence B, Holden J, Haytowitz B. 2009. Plant breeding for human nutritional quality. Plant Breed Rev 31:325–92.




About Author / Additional Info:
I am currently working as a Scientist (ICAR-ARS) from Indian Agricultural Research Institute.