Antioxidants

[Guru]

Tomatoes in diluted seawater significantly increased the levels of antioxidant

Growing tomatoes in diluted seawater significantly increased the levels of antioxidant vitamins C and E, says new research from Italy.
The research, focusing on standard 'salad' tomatoes and varieties genetically engineered for ripening, suggests opportunities for antioxidant-enhanced fruit and extracts produced in parts of the world with critical water shortages.

"The controlled use of alternative water resources, such as diluted seawater, could be a valid tool to face drought in the Mediterranean region," wrote the authors, led by Riccardo Izzo, in the Journal of Agricultural and Food Chemistry.

"Our results show that the antioxidant-related nutritional value of tomatoes is significantly improved when the fruits are picked at the red-ripe stage and when the plants are exposed to moderate salinity stress conditions, such as those determined by the application of diluted seawater (10 per cent)."

Tomatoes are a valuable source of nutrients, including beta-carotene, vitamins C and E, and lycopene, a potent antioxidant that gives the fruit its characteristic red colour.

Recent studies have linked tomatoes and their extracts to reducing the risk of several diseases, such as prostate cancer, and lowering inflammation that may cause hypertension and heart disease.

Researchers from the Universita di Pisa and the Universita degli Studi della Tuscia looked at the effect of diluted seawater and ripening on four cultivars of tomato - Jama and Gimar WT (classed as "salad" tomatoes) and Gimar gf (gf is a "stay green" mutant gene) and Gimar nor (nor is characterized by a reduced synthesis of lycopene and beta-carotene).

Izzo and co-workers report that ripening and growing the tomatoes under saline (salty) conditions induced oxidative stress in the fruit, and resulted in increased production of antioxidants. Moreover, the sensitivity of the cultivars to the saline conditions was genotype-dependent.

"The genotypes cv. Jama and Gimar gf line showed increases in ascorbic acid [vitamin C], lipoic acid, and alpha-tocopherol [vitamin E] during both ripening and salt treatment whereas total ascorbate and tocopherols decreased in the berries from salt-treated plants of Gimar wild type," they wrote.

"The mutant gene gf was found to confer a noticeable level of salt tolerance to the fruit in terms of antioxidant response," they said.

More research is needed, as well as investigation of whether the growing conditions affect carotenoid content of the fruit, particularly lycopene, the antioxidant pigment reported to be behind the major health benefits of the fruit.

Source: Journal of Agricultural and Food ChemistryPublished on-line ahead of print, ASAP article, doi: 10.1021/jf0634451"The influence of diluted seawater and ripening stage on the content of antioxidants in fruits of different tomato genotypes"Authors: C. Sgherri, F. Navari-Izzo, A. Pardossi, G.P. Soressi, R. Izzo