Physical and Physicochemical Characteristics, Bioactive Compounds, and Antioxidant Activity of Cladodes from Erect Prickly Pear Opuntia stricta (Haw.) Haw.

Abstract

Opuntia stricta (Haw.) Haw. is well adapted to arid and semiarid regions and has great potential for industrialisation. One- to four-year-old cladodes of this species harvested in Drâa-Tafilalet region in the southeast of Morocco, were characterised by examining physical and physicochemical parameters. Their bioactive compounds and antioxidant activity were also investigated. The cladode age had a significant impact on all the studied characteristics except some morphological parameters. Cladodes of different ages have a nutritional value comparable to a wide range of vegetables, particularly in terms of calcium, potassium, betalain, total polyphenol, and vitamin C contents. They are very rich in calcium (37.8-42.5 g/kg of dry matter (DM)) and have high betalain content. The content of phenolic compounds (133.9-165.0 mg gallic acid equivalent (GAE)/100 g DM) is especially noteworthy. These cladodes also contain very high amounts of vitamin C, especially the one-year-old cladodes (8.1-18.5 mg GAE/100 g DM). The recorded flavonoid contents vary from 3.8 to 7.6 mg of quercetin equivalent per 100 mL of cladodes mash. Condensed tannin contents range from 10.9 to 21.8 μg/100 mL of cladodes mash. Chlorophyll and carotenoid contents also vary from 5.55 to 23.76 and from 1.9 to 6.0 mg/100 g DM, respectively. One- and two-year-old cladodes are rich in total soluble solids (TSS) and ash with high total titratable acidity (TTA), compared to three- and four-year-old cladodes. Four-year-old cladodes have the highest TSS/TTA ratio, while two-year-old cladodes are the wealthiest in betalains with a dominance of indicaxanthins (yellow pigments). The oldest cladodes have the lowest inhibitory concentration (IC50) for antioxidant activity. Three-year-old cladodes have some traits significantly different, which may have resulted from physiological changes related to their great buds emission at this age. This study highlights the nutritional and functional potential of Opuntia stricta cladodes and the importance of their valorisation, particularly in agri-food and pharmaceutical industries.