The cactus fruit belongs to the Cactaceae family and is native to the arid and semi-arid
regions of the world, where the production of more succulent food plants is severely
limited.
Opuntia stricta
Haw, fruits have recently invaded the harsh dry rangelands of
the Laikipia Plateau of North-eastern Kenya. These cactus fruits contribute immensely
to the nutrition and food security needs of humans living in Laikipia. Despite the health
benefits of these fruits, the cactus plant faces the possibility of extinction due to adverse
effects of the prickly fruit when ingested by the livestock belonging to the local
communities in Laikipia. The present study, therefore, was designed to assess the
chemical composition, bioactive compounds and their health promoting properties in
Opuntia stricta cactus fruits. The results showed that the cactus pulp is a rich source of
ascorbic acid (60 mg/100 g), minerals (622 mg/kg P, 12.8 mg/kg Ca, 38 mg/kg Fe and
91 mg/kg Na), and sugars (18.5 mg sucrose, 10.9 mg glucose and 6.9 mg fructose). The
seeds contained significant amount of protein (4.13%), oil (11.5%), fibre (12.3%), β-
carotene (56 μg/100 g) and total carotenoids (289 μg/100 g). The seed oil contained
high levels of linoleic (70%), palmitic (12.5%) and stearic (12.3%) acids. The main
fatty acids were linoleic, oleic, palmitic and stearic acids with high unsaturation level
(83%). The principal amino acids in the fruits were arginine, tyrosine, glutamic acid,
proline and aspartic acid. The cactus whole fruits exhibited remarkable levels of total
phenols (1.6 g/100g), flavonoids (197 mg/100g), tannins (1.5 g/100g) and phytates (2.6
g/100g). The phytochemical extracts demonstrated high antioxidant activity in terms of
FRAP assay (1.2-6.9 μg/mM Fe (II) reducing power) and DPPH assay (73-86%). The
anti-diabetic effect of the extracts showed strong inhibition (> 50%) of α-glucosidase
as compared to the α-amylase inhibition. Thus, consumption of
O. stricta fruits could
meet the key nutritional requirements and help to address the double burden of food
insecurity and chronic diseases among communities living in the drylands of Kenya.
The results of this study could help inform the public on the nutritional and health
benefits of the Opuntia cactus fruit and address issues raised by the media on the
possible eradication of cactus plants in Laikipia and other drylands regions of Kenya.