Background. As a by-product of tropical fruit juice industry, passion fruit peel is a valuable functional food.
It is rich in antioxidants. To determine its potential antioxidant properties of passion fruit peel, this study
aimed to evaluate the effect of extraction conditions on total phenolic content and antioxidant activity.
Methods. The extraction conditions were selected from different percentages of ethanol (0-100%, v/v), extraction
times (60-300 min), and extraction temperatures (25-60°C) that based on the optimal percentage of
DPPH radical scavenging activity. The selected extraction condition was applied for further determination
of total phenolic content (TPC) of the passion fruit peel extract using Folin-Ciocalteu reagent assay, while
the antioxidant activities were evaluated using DPPH and ABTS radicals scavenging assays, ferric reducing
antioxidant power (FRAP), and β-carotene bleaching (BCB) assay. The best extraction conditions were 40%
ethanol, 60 min extraction time, and extraction temperature of 30°C.
Results. The chosen extraction conditions have contributed to the high TPC and antioxidant activity of passion
fruit peel. The levels of antioxidant activity obtained from the passion fruit peel were also lower compared
to BHA and α-tocopherol. Positive correlations were observed between TPC and antioxidant activities
as assessed by DPPH, ABTS, FRAP, and BCB assays.
Conclusion. As a waste of passion fruit consumption or by-product of fruit juice industry, its peel could be
considered as a potential source of natural antioxidant for possible functional food and industrial applications.