Processing and storage influence on scavenging activity of fruit juices

Özet

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.