Effects of pectinase concentration, ultrasonic time, and pH of an ultrasonic-assisted enzymatic process on extraction of phenolic compounds from orange processing waste

In this research, extraction of phenolic compounds from orange processing waste was investigated by combination of ultrasound and enzymatic processes using ethanol as the solvent. In order to achieve the maximum total phenolic content and extraction yield, and the minimum hue angle of the extract, optimal conditions of ultrasonic enzymatic treatment using ethanol as the solvent (UET-ES) were determined. The obtained optimal conditions are as follows: the pectinase enzyme concentration of 0.5%, the ultrasonic time of 120 min, and the pH of 4 using response surface methodology. The extract of optimal UET-ES compared to the extracts of ultrasonic enzymatic treatment using water solvent and maceration treatment using ethanol solvent (MT-ES) had an improved antimicrobial effect against two foodborne pathogens of Staphylococcus aureus and Escherichia coli. The results of Fourier transform infrared spectroscopy showed similar spectra of the extracts obtained through either the optimal UET-ES or MT-ES. Thus, degradation or alteration in functional groups of the extracts obtained through either of the two methods has not occurred.