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Polyphenolic compounds
In order to confirm the authenticity of the fruit juices, researchers
at the Department of Analytical Chemistry of the University of the
Basque Country (EHU-UPV) are trying to identify their fingerprints, as
it were, using a family of chemical compounds naturally present in all
fruit and known as polyphenols. There are thousands of polyphenols
amongst the various species in the vegetable kingdom, with differences
both in the number of particular polyphenols present in each vegetable
species as well as in the quantities found. Thus, different fruits
have specific polyphenolic differences.
In order to analyse polyphenols present in each for each fruit,
researchers at the EHU-UPV used a high-performance liquid
chromatography technique (HPLC), through which they culled information
about what particular polyphenols are present in each fruit and in
what quantity. This enables the study of the differences in the
polyphenols between one fruit and another.
In any case, to be more certain of these polyphenols profiles, the
confirmation is needed of the identity of each one of the polyphenols
appearing in these profiles. To this end, a mass spectroscopy (MS)
analytical technique was employed.
Orange, mandarin, lemon ...
A total of 16 fruits (Orange, mandarin, lemon, grapefruit, etc.),
grown in Spain, were studied. In each case a study of the various
varieties of each fruit was undertaken � up to 77 varieties, in order
to know the common points of all fruits, and their differences.
Beatriz Abad has found, amongst other things in her PhD, a quite
exclusive marker for lemon and three for grapefruit. She has also
shown that using several markers instead of one increases the
probability in detecting the food fraud. Moreover, she observed key
differences in various �prints� and, using certain statistical tools,
showed that such differences provide a quite reliable degree of
accuracy in the detection of some mixtures of juices. For example,
detecting the presence of grapefruit in orange juice is very sure and
relatively easy; detecting the presence of lemon juice in orange juice
is also quite accurate; but detecting the presence of mandarin oranges
in orange juice is much more difficult and not very reliable, given
that the mandarin and the orange are very similar in their �prints�.
To date they have defined the polyphenolic profiles or polyphenolic
�fingerprints� of the various juices from genuine fruit. The next step
is currently being carried out by researchers at the EHU-UPV �
applying these �prints to existing commercial juices on the market in
order to detect possible adulterations or frauds.
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