Optimization of Ultrasonication Probe-Assisted Extraction Parameters for Bioactive Compounds from Opuntia macrorhiza Using Taguchi Design and Assessment of Antioxidant Properties

Opuntia macrorhiza, commonly referred to as red prickly pear, is a type of cactus fruit. The Opuntia macrorhiza (OM) fruit is rich in polyphenols and contains a high amount of ascorbic acid and betalains. The fruit peels have demonstrated many biological abilities, including antioxidant, antifungal, and antibacterial activities. Ultrasound probe-assisted extraction (UPAE) is a highly promising method for efficiently extracting valuable molecules from natural sources. The objective of this study is to optimize the parameters of UPAE, including the appropriate solvent, liquid-to-solid ratio, extraction duration, and pulsation level. The aim is to maximize the yield of bioactive compounds (polyphenols, betalains, and ascorbic acid) from OM fruits (pulps and peels) and assess their antioxidant activities using Taguchi design. The optimal extraction conditions through the partial least squares method for OM pulp were determined to be aqueous extraction for 12 min with a liquid-to-solid ratio of 60 mL/g and 48 pulses/min, while for OM peels they were determined to be aqueous extraction for 20 min with a liquid-to-solid ratio of 60 mL/g and a pulsation of 48 pulses/min. The optimum UPAE conditions were compared with the values obtained from the optimum extraction under stirring extraction (STE). Overall, UPAE exhibited higher yields than STE. The obtained total polyphenol content ranged from 10.27 to 13.07 mg gallic acid equivalents/g dry weight, while the betalain content ranged from 974 to 1099 μg/g dry weight. Overall, these fruits demonstrated potential as new components for food and medicinal uses due to their good health effects and lack of toxicity.