Physicochemical properties and antioxidant activity of Korean cactus (Opuntia humifusa) cladodes

Physicochemical properties and antioxidant activity of Korean native cactus (Opuntia humifusa) cladodes (KCC) were investigated to evaluate the possibility for its application in new health functional foods. The KCC showed a high amount of crude ash (201.2 g·kg^-1 DW), characterizing Ca (1,967.8 mg·100 g^-1 DW), Mg (1,411.2 mg·100 g^-1 DW), K (1,269.6 mg·100 g^-1 DW), and P (1,110 mg·100 g^-1 DW) as the major minerals, as well as a high total dietary fiber (503.3 g·kg^-1 DW) including soluble dietary fiber (233.2 g·kg^-1 DW). The water holding capacity (WHC), oil holding capacity (OHC), and swelling power of KCC were 20.6 g·g^-1, 2.6 g·g^-1, and 16.8 mL·g^-1, respectively. The viscosity of a 100 g·L^-1 KCC suspension showed a non-Newtonian flow behavior with shear thixotropy and time dependency. The ethyl acetate fraction from an 80% ethanol extract of KCC showed the highest antioxidant activity as well as the highest total phenolic (112.8 g·kg^-1 fraction) and flavonoid (89.7 g·kg^-1 fraction) contents compared to other fractions. The most abundant phenolic compound within the ethyl acetate fraction was taxifolin (13.97 g·kg^-1 fraction). The results suggest that KCC could be used as potential sources of Ca and dietary fiber as well as a natural antioxidant. It might be possible to manufacture functional food products using the unique physical properties of KCC.