Variation in Chemical Composition and Antioxidant Activity of Fresh Tomato Fruit: Combined Effect of Cultivar and Storage

Tomato (Lycopersicon esculentum Mill.) is one of the most consumed vegetables in the world and
probably the most preferred garden crop. It is a key component of the Mediterranean diet, commonly
associated with a reduced risk of chronic degenerative diseases. Currently there are a large number
of tomato cultivars with different morphological and sensorial characteristics. Its consumption brings
health benefits, linked with its high levels of bioactive ingredients, including carotenoids such as β-
carotene, a precursor of vitamin A, and mostly lycopene, which is responsible for the red colour,
vitamins in particular ascorbic acid and tocopherols, phenolic compounds including hydroxycinnamic
acid derivatives and flavonoids, and lectins. The content of these compounds is variety dependent.
Besides, unlike unripe tomatoes, which contain a high content of tomatine (glycoalkaloid) but no
lycopene, ripe red tomatoes contain high amounts of lycopene and a lower quantity of glycoalkaloids.
Current studies demonstrate the several benefits of these bioactive compounds, either isolated or in
combined extracts, namely anticarcinogenic, cardioprotective and hepatoprotective effects among
other health benefits, mainly due to its antioxidant and anti-inflammatory properties.
This study intended to evaluate the influence of different postharvest cooling conditions in the
chemical composition, antioxidant activity and microbiological contamination of tomato cultivars
namely: Cereja, Chucha, Rama and Redondo. Pink fruits were kept for 15 days under three different
storage temperatures (6ºC, 12ºC and 25ºC) during which their lycopene, ascorbic acid contents, total
phenolics and antioxidant activity were evaluated every three days. Counts of colony forming units of
coliform bacteria, yeasts and molds and the presence of Escherichia coli, were determined before and
after 15 days of storage. All studied parameters revealed that temperature and storage duration
caused statistically significant differences in nutritional values of every cultivar. It was observed an
increase in the lycopene concentration and antioxidant activity with temperature and storage duration.
The phenolic and ascorbic acid contents showed a slight increase during storage at every
temperature. Microbial contamination was only found in cultivars that grew in direct contact with the
soil (Chucha and Redondo) and bacterial population increased exponentially with storage
temperature. Our results indicate that the ideal temperature to maintain optimal physiological,
biochemical and microbiological profiles of the cultivars studied is 12ºC and that the cv. Rama fruit is
the most suited for consumption in natura.