Antioxidant Capacity and Correlation with Phenolic Compounds and Carotenoids in 40 Horticultural Commodities

The consumption of fresh fruits and vegetables has been correlated with better health and prevention of several illnesses. Fruits and vegetables contain many phytochemicals, such as phenolic compounds and carotenoids, many of them are antioxidants. The objective of this work was to determine the antioxidant capacity (AOC) of 40 horticultural commodities sampled from the markets in Queretaro, Mexico, and correlate it with their phenolic and carotenoid content. AOC was determined by FRAP (ferric ion reducing antioxidant power) and DPPH (2,2-difenil-1-picril-hidrazil). Total carotenoids and total phenolic compounds were measured spectrophotometrically. Results showed great variations between the different commodities. Fruits that had the highest AOC were red bell pepper, guava, 'Ataulfo' mango, yellow bell pepper, 'Manila' mango, green bell peppers, and soursop. Those that had the lowest AOC were carrots, lettuce, black sapote, cucumbers and celery. Hydrophilic extracts of most commodities had higher AOC than the lipophilic extracts. Commodities that had the highest carotenoids content were carrots, celery, yellow and red bell peppers, and papaya. Commodities with the lowest carotenoid content were radish, prickly pear, pineapples, pears, onions, black sapote, banana and apples. Most commodities had high phenolic content. Those with low phenolic content were carrots, limes and white onions. AC measured by FRAP correlated positively with total carotenoids content in red bell peppers, 'Red Delicious' apples, limes and guava, and correlated positively with total phenolic content in avocados, soursop, tomato, 'Manila' mango, papaya and pears. AOC measured with DPPH correlated positively with total phenolic content in hot peppers, limes, 'Tommy Atkins' mangoes, melons, oranges and papaya, and correlated positively with carotenoids content in guava, tomatoes, lettuce, limes and yellow bell peppers.