Three fractions (peel, pulp and aril) of gac fruit (Momordica cochinchinensis Spreng) were investigated for
their phytochemicals (lycopene, beta-carotene, lutein and phenolic compounds) and their antioxidant
activity. The results showed that the aril had the highest contents for both lycopene and beta-carotene,
whilst peel (yellow) contained the highest amount of lutein. Two major phenolic acid groups: hydroxybenzoic
acids and hydroxycinnamic were identified and quantified. Gallic acid and p-hydroxybenzoic
acid were found in all fractions. Ferulic acid and p-hydroxybenzoic acid were most evident in pulp.
Myricetin was the only flavonoid found in all fractions. Apigenin was the most predominant flavonoid
in pulp (red), whereas rutin and luteolin gave the highest content in aril. The extracts of different fractions
exhibited different levels of antioxidant activity in the systems tested. The aril extract showed
the highest FRAP value. The greatest antioxidant activities of peel and pulp extracts were at immature
stage, whereas those in the seed extracts increased from mature stage to ripe stage. The contents of total
phenolic and total flavonoid in peel and pulp decreased during the fruit development stage (immature
> ripe fruit) and subsequently displayed lower antioxidant capacity, except for the seed.