4. Conclusions
By virtue of its appearance and based on spectral data obtained
from a double concentrated tomato puree after thermal treatment,
it follows that lycopene was probably subject to both degradation and isomerization processes. Processing at temperatures 120 C
provided the evidence that contribution of non-enzymatic
browning reaction products with antioxidant activity (Maillard's
products) should be taken into account. The more efficient
extractability of carotenes should be ruled out neither.
Storage of double concentrated tomato puree under controlled
temperature- and light-conditions has possibly led to cis-trans re-
isomerization of lycopene, whereas the storage of hexane solu-
tions resulted in severe trans-cis isomerization.
The change of color and flavor of tomato product which takes
place during processing and storage should expectedly be accom-
panied by reduced nutritional value of proteins. Moreover, whether
or not the advanced glycosylation end-products (AGEs) formed
during non-enzymatic glycation between proteins and carbohy-
drates play a role as uremic toxins is still under investigation (e.g.,
Glorieux, Schepers, & Vanholder, 2007; Henle, 2003; Vanholder,
et al., 2003).
One of the questions posed above, i.e., whether or not spectro-
photometry may provide useful data about the fate of finished to-
mato products when exposed to the additional thermal treatment
can now be answered. We believe that spectrophotometry is
indeed capable of providing a quick and reliable insight about the
possible deterioration of nutritional value of such products. Since
minimizing the loss of sensory and nutritional quality and maxi-
mizing the safety of meals ultimately to be served on plate are all a
necessity, the risk of additional heating of the processed tomato
foods when manipulated in the household/kitchen should be fully
understood and quickly assessed.