The
Nopal cactus (Opuntia ficus-indica (L.) Mill.) is a succulent plant
renowned for its exceptional biological adaptability in semi-arid environments.
It represents a valuable botanical resource rich in bioactive compounds with
potential applications in pharmaceuticals, cosmetics, and functional foods [1].
Despite its vigorous growth in the harsh climate of Phu Yen Province, Vietnam,
systematic studies detailing its anatomical traits, phytochemical profile, and
post-harvest thermal processing dynamics remain scarce. This study investigates
the anatomical characteristics of the cladode, the effect of drying
temperatures on moisture desorption kinetics, experimental repeatability
(%RSD), and the stability of the nitrogenous betalain pigments. Furthermore, the
in vitro ABTS•+ radical scavenging capacity of the extracts
was evaluated.
Histological examination via double-staining light microscopy revealed
a highly developed water-storage parenchyma composed of large, thin-walled
cells, a stomata-bearing epidermis, vascular bundles containing spiral xylem
vessels, and abundant calcium oxalate druses (sphaeraphides) [3].
Thermal drying kinetics demonstrated that moisture desorption was
temperature-dependent. However, betalains proved thermolabile, undergoing
accelerated thermal degradation at higher processing windows. The fresh extract
(M2) demonstrated an outstanding ABTS•+ radical scavenging capacity
with an IC₅₀ value of 48.39 µg/mL, which closely approached the antioxidant
capacity of pure ascorbic acid (IC₅₀ = 43.43 µg/mL). Convective oven-drying at
a moderate temperature of 40°C achieved high experimental repeatability (%RSD
< 1%) while protecting the thermolabile betalains against severe
degradation. These findings highlight the tremendous potential of the Phu Yen
Nopal cactus as a high-quality source of natural antioxidants for functional
and dermo-cosmetic applications.
