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Processing and Bioavailability (WG2) page 33
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C. Second transformation
12 Addition of ingredients (lipophilic
or hydrophilic)
D
O
13 Cooking (industrial and domestic) D
O
D The lipid ingredients solubilize the lycopene
O In soluble forms the reactions are easier
D The lipid ingredients solubilize the lycopene
O In soluble forms the reactions are easier and
the high temperatures activate the cinetics
The two points are treated together, because the domestic or industrial preparations of
sauces forecast the cooking with fatty ingredients and the references do not distinguish the
two possibilities (with or without).
Survey of references
Most of the scientific literature examined shows that industrially processed products,
above all those which are formulated (i.e. those in which the tomato is not the only ingredient)
contain more lycopene, and in a form more readily assimilated by man.
In particular, the studies by Rao et al. (1998), Gärtner et al. (1997), and Stahl and Sies
(1992a) underline the greater assimilation properties of lycopene as a result of a diet based on
concentrate rather than on an equivalent quantity of fresh tomatoes.
The work of Böhm (1999) is more complex, and is linked to a complete diet, whereas that
of Lerici et al. (1997), refers in general to the antioxidant property. The study by Lindley
(1998) is also of a general nature.
Schierle et al. (1997) evaluated the amount of lycopene isomers (all-trans lycopene, 5-cis
lycopene, 9-cis lycopene, 13 and 15-cis lycopene) in various tomato-based commercial
products. Samples were solvent extracted, the extracts were purified by aluminium oxide
column chromatography and then injected in the HPLC system, which allowed for the
separation and quantification of the lycopene and β-carotene isomers. The effects of the
analytical procedure on lycopene isomerisation were also evaluated, showing that the
percentage of all-trans lycopene increased or decreased by approximately 2-7%, depending
on the initial concentration. Food analysis showed that the proportion of all-trans lycopene
varied from 96% of total lycopene in preserved tomato paste down to 77% in tomato ketchup,
67% in bolognaise sauce and 35% in a long-term cooked spaghetti sauce prepared from
canned tomatoes. In order to study the effects of the presence of oil on lycopene