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Processing and Bioavailability (WG2) page 43
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Conclusions
An important aspect of this Concerted Action was to verify the contribution of the
processed tomato to the human diet; the tomato being the primary, and usually the only,
source of dietary lycopene. An attempt has been made to establish accurately the content, type
and bioavailability of lycopene intake through industrial derivates, also taking into account
the events occurring during the transformation processes and/or resulting from subsequent
storage, distribution and final handling on the part of the consumer.
An initial observation is that very few data are available on the antioxidant components
of tomato other than lycopene and carotenoids. The interest in lycopene is justified by its high
concentration in tomatoes, which represent its main dietary source, and by its demonstrated
antioxidant activity both in vitro and in vivo. Nevertheless, it is well known that the
antioxidant activity of food is usually due to the combined action of many food constituents,
which often act with synergistic mechanisms. A more profound knowledge of the other
antioxidant components of the tomato and of their fate during processing and storage is
needed to understand and optimise the nutritional properties of tomato products.
Data and information supplied by scientific literature on lycopene degradation during
common tomato processing such as heat sterilisation, concentration by evaporation and
dehydration and also for storage of processed tomato products, though sometimes inconsistent
or not completely clear, allow for some general conclusions and comments. Since the
operating conditions applied to the tests are either not well defined or do not correspond to
those used for industrial treatments, the results should be considered as being often unreliable.
Also, the above mentioned studies are incomplete because they only aimed to measure the
lycopene content, not its bioavailability, which is most important for the nutritional quality of
the product.
The data seem to suggest that lycopene is stable to heat treatments for tomato
concentration and cooking but less stable during processed tomato storage even at low
temperatures and in the absence of oxygen, particularly for powders and for products
submitted to treatments which have damaged the cell walls and which have consequently
reduced the protective effect concerning lycopene coagula. Exposure to oxygen, high
temperature and low water activity may cause lycopene degradation. With regard to lycopene,
researchers substantially agree in considering this compound stable to commercial production
processes, in terms of both degradation and isomerisation rate. Even air-drying, which is a