ANTIOXIDANT PROPERTIES OF HYDROPONIC CHERRY TOMATO CULTIVATED IN DESALINIZED WASTEWATER

Abstract

Tomato consumption is associated to a decreasing of the risk to acquire some types of cancer and cardiovascular diseases. The aim of the present work was to evaluate the use of desalinization wastewater in the production of hydroponic cherry tomato, as well as to determine the antioxidant properties of the fruits obtained though this process. The experiment was carried out in a one-way classification, with four plants with five clusters per workbench, using a nutrient film technique (NFT) system with 35 L of nutrient solution with a flowing rate of 3.0 L/min. Four replicates were done for the different treatments with salinity levels characterized by the values of electric conductivity (EC) applied for cherry tomato. An EC value of 3.0 dS m -1 corresponded to the control nutrient solution. Other EC values (6.0 and 9.0 dS m -1 ) were obtained by adding desalinated wastewater. The production period for five clusters per plant was 116 days, from seeding to the last harvest. The first fruits were harvested after 91 days for all the treatments, and were analyzed for the levels of ascorbic acid (vitamin C), lycopene and total phenolics; and for the antioxidant activity (using ABTS assay). If tomato production in an NFT system is aimed to be three times per year, the productivity can be estimated in approximately 92.7, 77.1 and 60.9 t ha -1 for the 3.0 (control), 6.0 and 9.0 dS m -1 treatments, respectively. The levels for lycopene, vitamin C and total phenolics; and the antioxidant activity for all the treatments ranged from 9.53 to 10.91 mg/100 g, 16.07 to 28.93 mg/100 g, 168.07 to 183.19 mg/100 g and 508.11 to 627.40 μmol TEAC/100 g, respectively. The results indicate that NFT hydroponic cultivation of cherry tomato, using desalinated wastewater in the formulation of the nutrient solution could be an attractive option for recycling this residue every time that the good productivity and antioxidant properties of the fruit are favorable for producing a functional food with beneficial characteristics for human health.