INVESTIGATIONOF FUNGICIDE AND HERBICIDE STATUS AND ANTIOXIDANT INDICES IN TOMATO VARIETIES AND PROCESSED TOMATO PASTE

Abstract

Tomato (Solanum lycopersicum L.) is a common fruit consumed in many homes with reported health promoting functions due to its antioxidant properties. Tomato fruits have poor shelf life, and are susceptible to pests and diseases which are sometimes controlled with pesticides. World Health Organization (WHO) estimated that there are 20,000 death and three million poisonings caused by pesticide misuse in the third world countries each year. Therefore, this present study examined fungicides and herbicides residues in two tomato cultivars, UTC (from two locations), and Roma in addition to and three commercially processed tomato pastes. The impacts of ripening and washing on the fresh tomatoes obtained from three locations, were also assessed. The antioxidant indices (total phenolic content, flavonoid content, DPPH, ABTS and NO radical scavenging activity) of the cultivars and processed tomato pastes were determined. The results showed a higher fungicide residue in Roma cultivar with the ripe and unwashed sample having the highest residue (0.079%), while the least residue was recorded in ripe and washed UTC cultivar (0.0029%).The result also showed a relatively lower fungicide residue in the processed tomato paste. However, the result of the herbicide residue of the studied cultivars showed a relatively higher herbicide residue in UTC cultivar obtained from location 1, with that of the ripe and unwashed sample having the highest residue (0.0082%). The least herbicide residue was recorded in unripe washed Roma cultivar, while the commercially processed tomato paste 1 had higher herbicide residues. Varying degrees of herbicide and fungicide reduction after washing was observed with ripe cultivar tomato from location 1 having the highest pesticide reduction (fungicide: 19.78%; herbicide: 19.89%). The antioxidant study showed phenolic content of the commercially processed tomato paste 1 (78.61 mg/g) to be higher than the fresh tomato cultivars, while paste 2 had the least content (45.48 mg/g). The UTC sample from location 1 had the highest 3 total phenolic content in the studied fresh ripe tomato, while the least content was observed in unripe UTC. Similarly, total flavonoid content (TFC), was highest in processed paste 1 (75.55 mg/g), while the least content was observed in paste 2 (41.59 mg/g), and UTC cultivar riped from location 1 had the highest TFC (64.21 mg/g), and the least content was observed in unripe Roma cultivar (38.52 mg/g). Similar results were obtained for DPPH, ABTS and nitric oxide (NO) radical scavenging activity activities, with UTC cultivar obtained from location 1 having the highest antiradical action. This result revealed that all the studied tomato fruit and paste possess an appreciable amount of antioxidant action and with some levels of fungicide and herbicide residues. Furthermore, residues in tomato fruits are significantly reduced by washing, with all values falling below the recommended maximum residue limit (fungicide: 0.1mg/g; herbicide: 0.2). The ripe UTC cultivar is the better tomato fruit. Therefore, the studied tomato fruits and paste can serve as a source of nutritional important molecules and also as a valuable bio-resource in the prevention of some certain diseases.