Seasonal variations in the antioxidant composition of greenhouse grown tomatoes

The carpometric characteristics, major antioxidant components, and antioxidant activity of three commercial New Zealand tomato cultivars, Excell, Tradiro, and Flavourine were studied in a greenhouse over a period of 8 months. The variations in the solar radiations received, temperature inside the greenhouse, and changes in the fruit load over the study period significantly (P < 0.05) affected the antioxidant components of tomatoes. The total phenolics and antioxidant activity in the three cultivars ranged from 169 to 579mg gallic acid equivalents/100g dry matter (DM) and 1684 to 3340 mu m TEAC/100g DM, respectively, during the study period. The mean total phenolics and antioxidant activity of the three cultivars was 62% and 39% higher, respectively, in summer (December-February) than in spring (September-November). The ascorbic acid and lycopene content of the three cultivars varied between 165 and 252mg/100g DM and from 19 to 73mg/100g DM, respectively, during the study period. The mean lycopene content of the three cultivars was 31% lower in the summer months than at other times of the study. This study indicates that the antioxidant components of tomatoes can vary considerably with the changes in environmental conditions within the greenhouse and the levels of antioxidants in greenhouse grown tomatoes could be elevated throughout the growing season by modifying the environmental conditions inside the greenhouses. (c) 2005 Elsevier Inc. All rights reserved.