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Composition of tomatoes and tomato products in antioxidants (WG1) page 19
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1. Tomato mutants exist which deliver high lycopene. One route chosen is to increase plastid
number. Therefore an alternative approach could be the increase of chromoplast number
within the tomato.
2. Another approach could be to store lycopene in the vacuole.
3. A further approach is to use carotenoid associated proteins to increase deposition of
lycopene.
These approaches are more technical challenging as the basic enabling research has
not yet been carried out.
5. Influence of maturity stages and storage on the antioxidant composition of
tomatoes
The colour and the composition of the fruit greatly vary during ripening. In the unripe
fruits, the green colour is associated with chlorophylls and a low quantity of carotenoids. It
should be noted that in these fruits the biosynthesis of carotenoids is active but the
carotenoids are immediately broken down due to photoprotective and antioxidant properties
(Giulano et al.1993, Fraser et al.1994). During the ripening period, the chlorophylls gradually
disappear and become undetectable 7 days after the breaker stage. Simultaneously, even
though the enzymatic activities of phytoene synthetase, phytoene desaturase and lycopene
cyclase are reduced, both the expression of genes coding for phytoene synthetase and
phytoene desaturase and the content in lycopene and β-carotene increase. At the turning stage,
lycopene content considerably increases and can reach 80-100 mg/kg fresh matter at red stage
(Giulano et al.1993, Fraser et al.1994).
The content in chlorogenic acid is the highest in earlier stages of fruit development
and rapidly decreases during fruit ripening reaching less than 20 mg/kg fresh matter at red
stage (cv Ailsa Craig and Pik-Red) (Aziz et al.1973). This evolution is similar for numerous
fruits (Buta and Spaulding 1997). While quinic conjugates of phenolics, like chlorogenic acid,
are declining, glucoside conjugates (p-coumaric-glucose) become high in mature stages,
especially in pulp (around 60 mg/kg fresh matter at red stage for the two cultivars previously
cited). Glucose derivatives were suggested as biomarkers for maturation by Fleuriet and
Macheix (1985). Rutin (or quercetin-3-rutinoside), specially located in tomato pericarp and