Ultrasound-assisted extraction of polyphenols from pineapple skin

Pineapple skin (PS) is among the major food wastes from canning industries which contributes to environmental pollution. Nonetheless, PS contains an appreciable quantity of valuable phenolic compounds that may have potential applications in pharmaceutical and cosmetics industries. Since much of the PS waste are discarded, recovery of this agro-industrial biomass for possible transformations into value-added products merit scientific attention. In this study, phenolic compounds were recovered from PS using a greener method of ultrasonic-assisted extraction (UAE). The study aimed to assess the effect of sonication time to extract the highest concentration of polyphenolics from the PP waste. It was demonstrated that the highest extraction yield (29.04 %) was obtained at 6.49 min sonication time, whereas maximum total phenolic content (TPC) and total flavonoid content (TFC) of 1078.68 ± 1.32 mg GAE/g DW and 1276.64 ± 5.92 mg QE/g DW, respectively, were attained following sonication at 5.92 min. These values seen here were considerably higher than that obtained using Soxhlet reflux extraction (24.95% and 7.98 mg GAE/g DW) and drying process (4.16 ± 0.24 mg GAE/100g DW and 76.93 ± 11.85 µg rutin equivalent/100g DW). The findings, therefore, envisioned the efficacious UAE method for a greener and higher recovery of polyphenolic compounds from PS waste.