Effects of enzymatic treatment on the chemical composition, antioxidant and rheological properties of cactus cladode juice

Abstract

Cactus (Opuntia ficus-indica), commonly referred as prickly pear or nopal cactus, belongs to the family Cactaceae. It has attracted domestic and international industries’ attention owing to its nutritional and health benefit potentials. In this project, the quality of the cactus cladode juice after treated with the enzymes Pectinex Ultra SP-L and Viscozyme was investigated in terms of total phenolic content (TPC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity. There were significant increases in the effectiveness of these enzymes as the concentration increased from 0.05 to 0.15% w/w. Among different concentrations, 0.15% w/w produced a higher yield and high-quality juice. Furthermore, the result indicates that prolonging the incubation duration could improve juice yield but this occurred only within the first hour of reaction, which the highest yield was obtained at 0.75 h. At these conditions, the combination of Pectinex Ultra SP-L and Viscozyme at ratio 1:1 (w/w) showed the most effective on juice yield improvement and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, while the highest total phenolic content was obtained when treating with Pectinex Ultra SP-L. Particularly as compared to the control sample, the juice yield increased from 53% to 76%, the TPC enhanced from 47 μg gallic acid equivalent (GAE)/mL to 70 μg GAE/mL, and the DPPH free radical scavenging activity improved from 277 μg ascorbic acid equivalent (AAE)/mL to 470 μg AAE/mL. Overall, the quality of cactus juice was better with enzymatic treatment than that of the untreated juice. The data also showed that the cactus juice behaved as shear – thickening fluids at room temperature.