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Processing and Bioavailability (WG2) page 22
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According to Rao and Agarwal ((1999), lycopene contents in canned tomato juice stored
at room temperature for 2 months did not change significantly. At 3 different storage
temperatures (4, 25 and 37 °C), lycopene levels did not change after 1 month of storage
Sharma and Le Maguer (1996a) studied the kinetics of lycopene degradation during the
storage of tomato pulp solids. Samples of fibre-rich tomato pulp, obtained by decanter
centrifugation, were stored under different conditions (vacuum and dark, dark and air, and air
and light) at –20°, +5° and + 25°C for 60 days. Lycopene loss was maximum (77.6%) at 25°C
in the presence of air and light. Lycopene degradation followed a pseudo-first-order kinetics.
The apparent reaction rate constant increased with the increase in storage temperature from
20° to 25°C under different storage conditions, and were the lowest under vacuum and dark,
confirming the potential detrimental effect of oxygen and light on lycopene loss. The authors
calculated the activation energy (Ea) values for lycopene degradation under the three different
storage conditions, finding non-statistically different Ea values ranging from 20 to 28'kJ/mol.
Freeze-drying and oven drying (25, 50 and 75'°C) of fibre-rich tomato pulp did not cause any
loss in lycopene content. However, after storage of dried samples at room temperature in the
dark, lycopene loss reached 97% in freeze-dried samples and 73-79% in oven-dried ones.
Although the moisture content of the differently dehydrated samples was not reported, it can
be assumed that freeze-dried samples were more readily oxidised because of the higher
surface exposure to oxygen and the lower moisture content.
Tamburini et al. (1998) found that the hot-break juice extraction technique lowers, but
less than 2%, the initial lycopene content because of the severe heat effect, although allowing
the tomato cell structure to remain almost unchanged preserves lycopene more efficiently
over time against the reactions that cause its destruction; in contrast, with other juice
extraction techniques (cold-break); owing to the lack of this protective effect on account of
the triggering of pectolytic reactions, an 8-15% decrease in lycopene content already occurs
after 4-6 months of storage.
A thesis study by Zanotti (1999) reveals that although lycopene remains substantially
unaltered in time, even under rather drastic storage conditions, a marked degradation of colour
occurs (see Fig. 3)
Time Lycopene ± std dev.. Lycopene ± .std dev.
(days) (ppm at 9°Bx) (mg/Kg of d.w.)
0 187.4 ab ±9.3 2082 ab ±103
30 183.8 b ±10.4 2042 b ±115
90 178.5 c ±15.3 1983 c ±170
165 180.5 c ±9.9 2006 c ±110