Organic and conventional vegetables: Comparison of the physical and chemical characteristics and antioxidant activity

The objective of this research was to compare the physical and chemical characteristics and antioxidant activity of organic and conventional carrot (Daucus carota), green pepper (Capsicum annuum) and lettuce (Lactuca sativa). Five representative samples of  conventional vegetables, certified organic and non-certified organic vegetables were gotten from farms and supermarkets in the city of Rio de Janeiro. The result shows that the organic carrot showed higher acidity (0.11 g % citric acid) and total sugar (5.68 g %) than those found in standard samples and  certified organic ones (p 0.05). It was observed that the vitamin C levels in carrot samples levels had no significant difference between the different forms of production (p>0.05). Conventional lettuce and certified organic pepper showed higher vitamin C than the other samples (p 0.05). Carrot and green pepper, with seal certification or not, showed higher capacity to reduce DPPH than the conventional ones, this suggests that the form of cultivation has a direct relationship with the nutritional values of the vegetables. Key words: Carrot, lettuce, green pepper; organic, conventional, antioxidant activity, physico-chemical analysis.