Optimization Of An Ultrasound-assisted Extraction Of Polyphenols, Flavonoids And Their Antioxidant Activity From Avocado Peel (Persea Americana Mill)

Abstract

This study investigated the significance of the processing factors in the ultrasound assisted extraction method for the extraction of polyphenols, flavonoids and their antioxidant activity from avocado peel (Persea americana Mill.) and subsequently optimized the process. The study employed a two-step optimization approach, where a suitable level of significant factors was identified using the one-factor-at-a-time method with four factors (ethanol concentration, solvent-to-solid ratio, ultrasound treatment temperature, and sonication time), and the optimal levels of the significant factors were determined using Box-Behnken Design. In this study, the factors that significantly affected the extraction yield of total phenolics were found to be ethanol concentration, ultrasound treatment temperature, and sonication duration. The effects of these three significant parameters were then chosen to conduct the Box-Behnken design. The results showed that the optimal conditions for simultaneous extraction of those three responses were 40.64% ethanol concentration, 60.72oC ultrasound treatment temperature, and sonication duration of 41.78 min. Under these optimized conditions, the yields of polyphenols, flavonoids, and their antioxidant activity were 53.21 ± 0.4 mg gallic acid equivalent/g dry basis, 9.60 ± 0.11 mg RE/g dry basis, and 75.20 ± 0.64 mg AAE/g dry basis, respectively. In conclusion, avocado peel is a good source of bioactive compounds, the ultrasound-assisted extraction method is effective and ecologically benign for extracting polyphenols and flavonoids, and the Box Behnken design proved to be effective in screening and optimization