Ultrasonic-Assisted Extraction of Phenols, Flavonoids, and Biocompounds with Inhibitory Effect Against Salmonella Typhimurium and Staphylococcus Aureus from Cactus Pear

Three experimental variables [methanol concentration, extraction time, and material-to-solvent ratio (w/v)] were optimized in the ultrasonic-assisted, Box-Behnken extraction of biocompounds (total phenols and flavonoids) from xoconostle (Opuntia oligacantha) to determine the antibacterial activity against Salmonella typhimurium and Staphylococcus aureus. The total phenols and inhibitory effect on Staphylococcus aureus were optimal with 10min of ultrasound and 40% methanol, and a ratio of 1:20 (w/v); the total flavonoids was optimal with 20min of ultrasound, 40% methanol, and a 1:30 ratio (w/v); and the biocompound effect on Salmonella typhimurium was optimal with 10min of ultrasound, 60% methanol and a ratio of 1:10 (w/v). The polynomial equations showed satisfactory accuracy in predicting the extraction yield. The total phenol content and Salmonella typhimurium and Staphylococcus aureus parameters were fit to a quadratic model, while for flavonoids, the fit was linear. The results showed that biocompounds extracted from xoconostle have a high inhibitory effect on Salmonella typhimurium and a moderate effect on Staphylococcus aureus. These xoconostle extracts can be used as a natural antibacterial additive in the food industry. Practical ApplicationThe use of natural antibacterial compounds in the food industry has been increasing. Xoconostle is the acidic fruit of the Nopal, or the cactus pear, which is endemic in the Americas. In this study, three variables of the ultrasound-assisted extraction of biocompounds from xoconostle were optimized for antibacterial activity using the surface-response Box-Behnken design, namely, the methanol concentration, extraction time, and material-to-solvent ratio (w/v). The results showed that the best conditions for the extraction of phenols and biocompounds with inhibitory activity against Staphylococcus aureus were the same, while the optimal conditions for the extraction of flavonoids and biocompounds with inhibitory activity against Salmonella typhimurium were different. The ultrasound-assisted xoconostle extractions of flavonoids, phenols, and biocompounds with antibacterial activity against pathogenic bacteria have potential applications as food additives.