Comparison of total phenolic content and antioxidant activities of freeze-dried commercial and fresh fruit juices

Abstract

Fruits contain various natural antioxidants and secondary metabolites which play an important role in human health. Fruit juices have been proposed as a convenient substitute for fresh fruit. In this study, the total phenolic content and antioxidant activity of various freeze-dried fresh fruit blends or fruit juices (Apple, lime, guava, mango, orange) were compared. Total phenolic content of the extracts was determined using Folin-Ciocalteu assay. Antioxidant capacity of the extracts was determined by 1,1-diphenyl-2picryl hydrazyl (DPPH) scavenging assay and tyrosinase inhibition assay. Guava contained the highest amount of total phenolic content among all the tested fresh fruit blend, while mango contained the highest amount of total phenolic content for the commercial fruit juice. Apple contained the lowest content of total phenolic in both fresh and commercial fruit juice. In the DPPH scavenging test, guava and mango still possessed the strongest antioxidant activity for fresh and commercial fruit juices. Commercial lime juice possessed the weakest antioxidant activity where no IC50 was able to obtain even up to 10 mg/ml. All of the commercial and fresh fruit did not show tyrosinase inhibition activity. The present study demonstrates the potential value of commercial fruit juice as the replacement of fresh fruit. However, only commercial mango and orange juices were able to maintain similar antioxidant activity and total phenolic content as fresh fruit. Key words: Fruit juices, 1,1-diphenyl-2picryl hydrazyl (DPPH), tyrosinase inhibition activity.