SCREENING OF ANTIOXIDANT ACTIVITIES AND THEIR BIOAVAILABILITY OF TROPICAL FRUIT BYPRODUCTS FROM INDONESIA

Objective: The objectives of this study were to investigate the antioxidant activities in peel and seed of six tropical fruits from Indonesia and to evaluate their bioavailability by in vitro digestion model.Methods: Six tropical fruits namely kapundung, matoa, papaya, rambai salak and soursop were used. The study measured antioxidant activities through 1,1-diphenyl-2-picrylhydrazyl (DPPH) method, thiobarbituric acid reactive substances (TBARS) assay, total phenolic and total flavonol content of the samples. Further, the bioavailability of the antioxidant was determined by in vitro gastrointestinal digestionResults: Matoa peel and salak peel exhibited high DPPH radical scavenging activity with a SC50values of 6.6 and 6.4 µg/ml, respectively. Soursop peel had the highest for inhibiting lipid peroxidation followed by matoa peel and salak peel. The highest value for total phenolic content had in salak peel (317.0 mg gallic acid equivalent (GAE)/g dry basis). Then, total flavonol content values in salak seed (96.7 mg quercetin equivalent (QE)/g dry basis) was the highest in this study. The antioxidant activity of matoa peel and soursop peel increased after being digested.Conclusion: The results obtained in the present study indicate that peels from matoa (Pometia pinnata) and soursop (Annona muricata L) could serve as potential sources of antioxidant for use in food or feed supplement, and pharmaceutical industries.Keywords: Antioxidant, Lipid peroxidation, Phenolic compounds, Fruit peel, Fruit seed, Tropical frui