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Composition of tomatoes and tomato products in antioxidants (WG1) page 48
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water. Vitamin C concentration was higher in fruit grown on vermicompost (about 150
mg/kg) than in fruit grown on the hydroponic substrates (about 60 mg/kg). This could be
related to a shading effect, as high rates of fertilizers on the hydroponic substrates promoted
foliage growth and shading of the developping fruit.
6.2.4.4. Ripening stage
In cv. Marglobe and Stokesdale, Murneek et al.(1954) showed that vitamin C content
of greenhouse tomatoes picked “green” and allowed to ripen at room temperature (22-
24.5°C.) increased from mature-green stage (110 mg/kg) to ripe (red) stage (200 to 260 mg/kg
according to fruit size). López-Andréu et al.(1986) graded the stages of ripeness of the
cultivar Vemone as follows : I (mature green), II (green yellow), III (yellow-orange), IV
(orange-yellow), V (orange-red), VI (red), VII (deep red). From I to VII, vitamin C content
increased from 84 to 180 mg/kg of fresh matter. The values were lower than those given in
the literature because in greenhouse with less direct sunlight the fruit contains less vitamin C
than field cultivated fruit. Normally the rise is sudden from the stage II. With plum tomatoes
(var. Heinz 9478) Shi et al.(1999) found that ascorbic acid content of whole fresh fruit
increased from the stage mature-light pink (175 mg/kg) to the stage mature-pink (209 mg/kg)
and to the stage mature-red stage (256 mg/kg). However, Abushita et al.(1997) found that for
Floriset cultivar, vitamin C content increased from green stage (130 mg/kg) to yellow stage
(240 mg/kg) then decreased until red stage (120mg/kg), most likely due to its antioxidant
function when the ripening cells absorb high amounts of oxygen as a result of increasing rate
of cell respiration (characteristic physiological change in climacteric fruits).
Giovanelli et al.(1999) evaluated the variation in the vitamin C content at seven stages
during vine and post-harvest ripening on the tomato cv. Moneymaker grown in a greenhouse.
Ascorbic acid content presented different patterns of variation with the ripening conditions :
in post-harvest-ripened fruit it decreased from about 200 mg/kg fresh matter to 150 then
increased to about 200 mg/kg fresh matter. In vine ripened fruit it first increased from about
200 mg/kg to 250 then decreased to roughly 150-200 mg/kg fresh matter.