The food composition tables, which are necessary tools for
nutritional and epidemiological studies, are representative of
food stuffs consumed in only raw state. These studies don’t take
into consideration the facts that, the concentration of nutrients
and their biological activity may be changed by processing
methods. The aim of this study is to investigate the influence
of processing/storing conditions on the free radical scavenging
activity of different fruit juices. Free radical scavenging activity
of fruit juices was determined by 2, 2-diphenyl-1-picrylhydrazyl
(DPPH) method. Different types of fruit juices showed different
values of scavenging activity. The free radical scavenging activity
was quite stable when fruit juices were incubated at 4 oC for 4 days.
When the freshly squeezed fruit juices were incubated under the
sun light for 4 days, orange juice retains its scavenging activity.
Lemon juices, mandarin and grapefruits lost more than 70% of
their scavenging activity, while tomato juices lost more than 50%
of its scavenging activity. Incubation of juices in boiling water for
60 minutes did not cause a significant loss of scavenging activity.
In conclusion, sunlight may degrade many nutrients including
the antioxidant. However, neither boiling nor freezing conditions
affected the scavenging activity of different juices.
Keywords: Juices, Antioxidants, Sunlight, Heat, Processing,