Abstract
Grapefruit is an important fruit crop in the world as well as in Pakistan. Phenolic compounds, antioxidants, carotenoids,
flavonoids and limonins are important health promoting substances which are present in grapefruit and are considered as
preventative against cronic diseases. Therefore, the objective of this study was to investigate the effects of harvesting times
on these substances. Fruits of two grapefruit cultivars i.e. Ray Ruby and Shamber were harvested at different dates viz. 1
st September, 1
st October, 1
st November, 1
st December and 1
st January during the both study years. The fruit harvested in the
month of December showed higher total phenolic compounds (172.25 and 176.62 mg GAE/100g), total antioxidants (72.30
and 79.14 %), total carotenoids (19.34 and 21.87 mg/100 g), total flavonoid contents (69.83 and 69.90 mg CEQ/100g), total
limonin contents (10.96 and 10.51 µg/mL), total pectin contents (10.65 and 10.81%), total glycoside limonin contents
(194.97 and 204.89 µg/mL) in Ray Ruby and Shamber cultivars of grapefruit, respectively. All other quality components
such as TSS, ascorbic acid and sugars were also increased up to December and then started to decline. It is concluded that the
I
st December is an optimum time for harvesting of both Ray Ruby and Shamber grapefruit cultivars in relation to health
promoting substances.
