Nutritional value and antioxidant content of seed-containing and seedless eggplant fruits of two cultivars grown under protected cultivation during autumn-winter and spring-summer

BACKGROUND: Due to their low carbohydrate and high antioxidant content, eggplants are beneficial for the human diet. At <15 degrees C, pollen production and fertility are reduced and plant-growth regulators may be used to set seedless fruit. Because only the agronomic effects of hormone are well-documented, we investigated the composition and metabolism during the development/maturation of seed-containing and seedless fruits of two cultivars grown over two seasons. RESULTS: The respiration rate of both seedless and seed-containing fruit decreased with development and maturation. In seedless fruit, starch content decreased at market maturity, whereas in seed-containing fruit starch increased. Respiration and starch were higher in spring-summer than in autumn-winter. Disaccharides were highest at market maturity, with sucrose generally higher in seed-containing fruit; monosaccharides were variable and protein content was reduced in seedless fruit. Phenols closely correlated with antioxidant activity and decreased with development; at market maturity in spring-summer phenols were higher in seedless fruit (Tsakoniki) or unaffected (Emi). Polyphenol oxidase and peroxidase activities were mostly higher in seed-containing fruit, but browning was higher in seedless fruit. CONCLUSIONS: Notwithstanding reduced protein and increased browning, seedless fruit at market maturity presented less starch, hence fewer calories, and more antioxidants (phenols) for the human diet than the corresponding seed-containing fruit. (C) 2017 Society of Chemical Industry