Different extraction conditions affected the TPC
and antioxidant activities of passion fruit peel. Passion
fruit peel extracted using the best extraction condition
(40% ethanol as extraction solvent, 30°C of extraction
temperature and 60 min of extraction time) had an
optimal antioxidant activity. A moderate level of TPC
(15.84 μg GAE/g sample) was determined in the passion
fruit peel extract, while the antioxidant activities
assessed using different antioxidant assays were varied.
Due to the moderate level of TPC as antioxidants
in the peel extract, the antioxidants could not be acting
as strong reducing agents to give lower EC50 and higher
TE values compared to the synthetic antioxidants.
However, the peel extract was able to give 68.54% of
inhibition activity for BCB assay. Therefore, the peel
of passion fruit is still considered as a good source of
antioxidant. It can also be used as potent source of
pharmaceutical ingredient. In future, more studies are
needed to identify the potential bioactive compounds
in passion fruit peel and the related health benefi ts.