An-Najah Staff

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Original research

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ABSTRACT

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,

Cooling.

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