Flow Behaviors of Fruit and Stem Extracts from Korean Cactus (Opuntia humifusa)

Water extracts from the fruit and stem of Korean cactus (Opuntia humifusa, OH) showed a prototypical pseudo-plastic behavior. The pseudo-plasticity was increased with increasing concentration and decreasing temperature. The extract from the stems showed higher shear stress, consistency, and yield stress than that from fruits. The flows were examined at different concentrations, temperatures, pH, and salt content. The activation energies from fruits and stems increased from 4.127×103 to 1.584×103 J/kg·mol and from 16.162×103 to 10.014×103 J/kg·mol, respectively, as concentration increased. The concentration-dependant constant K1 from fruits and stems decreased from 0.233 to 0.185 mPa·s and from 30.476 to 66.198mPa·s, respectively, as temperature increased. The viscosity from fruits and stems increased as pH increased, while decreased as Ca2+ concentration increased. The unusual flow behaviors of stems and fruits might play a major role in developing food products using OH extracts.