The antioxidant activity of tomato. II. Effects of vine and post-harvest ripening

The variation in the antioxidant content (lycopene, P-carotene, ascorbic acid and total phenolics) was evaluated on two tomato genotypes (cv. Moneymaker, Normal red and Crimson) during vine and post-harvest ripening. Tomatoes were sampled and analyzed at 7 ripening stages according to the colour value (a*/b*). The a*/b* value increased as a function of time for post-harvest ripening experiments during 12 days (from an initial value of about -0.5 to a final value of about 2.0), then the curve tended to level off. Ripening conditions affected both the antioxidant accumulation kinetics and the final content, which was higher in post-harvest-ripened fruits. This accumulation continued throughout the ripening process, even when other significant composition parameters remained substantially unchanged. In particular, lycopene mainly accumulated in the very last period of ripening, and its content was not linearly related to colour changes. Carotenoid accumulation during post-harvest ripening followed an exponential rate up to high concentration values in the very last period of ripening, before over-ripening symptoms became evident. Ascorbic acid variation followed different profiles in vine- and post-harvest-ripened tomatoes, reaching higher final concentrations in post-harvest-ripened fruits. Total phenolics concentrations were also higher in post-harvest-ripened tomatoes. Antioxidant accumulation and other ripening indexes were not significantly different in the two tomato genotypes. Soluble solids accumulation was slightly higher in vine-grown tomatoes.