ULTRASOUND-ASSISTED EXTRACTION OF POLYPHENOLS FROM ISABEL GRAPE PROCESSING RESIDUES

Objective: This work aimed to study the effect of ultrasound amplitude and application time on the extraction of polyphenols from Isabel grape processing residues. Methods: Phenolic compounds were extracted by a conventional method (mecanical agitation) and ultrasound-assisted extraction (UAE). For UAE, the influence of amplitude levels (75-373 W/cm2) and application time (2-10 min) on total phenolic compounds (TPC), total anthocyanins content (TAC), total tannin content (TTC), antioxidant capacity (AC), and total energy consumption (TEC) was studied using the response surface methodology (RSM). Results: RSM demonstrated to be an effective technique for investigating the effects of ultrasound intensity and processing time on TPC, TAC, TTC, and AC. Greater extraction of phenolic compounds, anthocyanins, and tannins was obtained with an increase in the amplitude level and time of ultrasound application. The results of the antioxidant capacity were proportional to the concentrations of polyphenols. In relation to energy consumption of UAE, it was larger than conventional extraction. Conclusion: Although the energy consumption was higher, UAE proved to be an efficient technique for grape residue polyphenols extraction.