Studies On Bioactive Components And Total Antioxidant Activity In Orange Juice

Fruits and vegetables, which are rich in vitamins and minerals, account for a large proportion in people's daily diet. Also, fibers, pectin and many other secondary metabolism elements found in fruits and vegetables are of quite beneficial to health. As the second largest producer of citrus, China is abundant in citrus genetic resources, where citrus fruits have been used in medicine and edibles since many years ago. In recent years, it has been found that citrus fruits contain many different bioactive components with antioxidant activities and specified health effects, which could protect against heart diseases and cancers, and are the main human dietary source of antioxidant compounds like flavonoids. Therefore, studies on how to exploit and utilize natural antioxidant in citrus fruits have become a hot research field.In this paper, the contents of antioxidant components in seven kinds of orange juices and their relative contribution to the antioxidant activities were analyzed, while the antioxidant activity was evaluated by three radical scavenging assays (Fenton-type reaction system, ABTS and DPPH). At the same time, the influences of different thermal treatments and different storage conditions on main antioxidant compounds and the total antioxidant activities were studied. The total antioxidant activity of 11 commercial orange juices, which include pasteurized pure juice and sterilized beverage containing minimum 10% of concentrated orange juice was also analyzed. The main research results were as follows:1. The contents of antioxidant components in seven kinds of orange juices were measured, which it separately ranged from 390.6 to 478.6 mg·L^-1 for Vc, 573.1 to 655.0 mg·L^-1 for polyphenols, 5.47 to 7.25 mg·L^-1 for carotenoids and 0.10 to 0.17 mg·L^-1 for limonoids. Among these seven different kinds of orange juices, statistically significant differences were found for the contents of Vc and polyphenols, which the highest was found in blood orange; while there were slight differences found for carotenoids and limonoids.2. The antioxidant activities of seven kinds of oranges were evaluated in three ways: the scavenging activities for ·OH were between 47.60% and 88.62% , with obvious difference among varieties, where Sekken Hayata and blood orange having the strongest, Qingjia the weakest. The scavenging activities for DPPH· were all above 50%, with no obvious differences among varieties, where Sekken Hayata having the relative high scavenging activity. The TEAC values measured by ABTS/K₂S₂O₈ system were from 4.79 to 6.09, with blood orange the highest and Jincheng the lowest. In (?)ummarization, it was suggested that blood orange had got the strongest total antioxidant activity.3. According to statistic analysis, there were positive relationships between the contents of Vc, polyphenols, carotenoids and the radical scavenging activities of ·OH and DPPH·, while for...