Science News 05/09/2011

The quality of light and the nutraceutical compounds in tomatoes

The UV-B rays are not necessarily harmful. According to the researchers of the University of Pisa they could be used to improve the healthy and nutritive properties of the tomato, renouncing to chemical or bioengineering treatments

The vegetal foods with a high content of healthy components are catching more and more the attention of the consumers. Epidemiological studies showed a strong correlation between the consumption of vegetables and a reduced risk of neurodegenerative ageing diseases.

Simple modifications of the culturing techniques can deeply influence the content of bioactive compounds, known as nutraceutic compounds, in those foods. Moreover, it is possible to select for cultivars that respond better to the treatments, producing higher quantities of bioactive fitochemicals.

At this purpose, the research activity of my group at the Agriculture Faculty of Pisa led at investigating the influence of the UV-B radiation of the sun spectrum, which is present in open air conditions but not in the greenhouses, on the accumulation of carotenoids and flavonoids in tomatoes.

We found that the presence of UV-B was able to induce in a low-content lycopene tomato cultivar a 20% increase of this important carotenoid, together with a three-times increment of the most represented of flavonoids, rutine.

We experimented the UV-B treatment of the vegetable also in the preservation stage, a period when vegetables normally loose part of their nutraceutic components and can be subject to the attack of pathogens. In tomatoes gathered at different maturation times, a one-hour illumination by UV-B lamps per day increased the total carotenoid content of the 50%. Moreover, the most interesting result was that this treatment induced a more than double increase of lycopene in the pulp, where the carotenoids are normally less concentrated than in the skin.

The practical applications of this technique, which is able to improve the healthy and nutritive characteristics of the tomato without using any chemical or bioengineering, are clear and easily implementable during the food preservation or distribution processes.

di Anna Maria Ranieri