Extraction of functional natural products employing microwave-assisted aqueous two-phase system: Application to anthocyanins extraction from mulberry fruits

Abstract

Abstract Microwave-assisted aqueous two-phase extraction (MAATPE) was applied to obtain anthocyanins from mulberry using ethanol/ammonium sulfate ((NH4)2SO4) as the biphasic extractant. The optimal conditions for anthocyanins extraction were determined by response surface methodology (RSM), which included 39% ethanol (w/w), 13% (NH4)2SO4 (w/w), a liquid-to-solid ratio of 45:1, and microwave exposure for 3 min at 32°C and 480 W, resulting in a maximum extraction recovery of 86.35 ± 0.32%. The main components of mulberry-extracted anthocyanin were effectively enriched through MAATPE extraction, as analyzed using high-performance liquid chromatography (HPLC). Fourier transform infrared (FT-IR) spectra analysis indicated that hydrogen bonding was the primary mechanism causing the extraction behavior of MAATPE. Scanning electron microscope (SEM) showed that MAATPE was more conducive to the dissolution of mulberry anthocyanins than ethanol and ATPE extraction. Moreover, antioxidant experiments showed that the mulberry anthocyanin extract obtained employing the MAATPE method exhibited better antioxidant activity in scavenging DPPH and ABTS free radicals. These results demonstrate that the MAATPE is a promising approach for the extraction of anthocyanins from mulberry. Moreover, mulberry-derived anthocyanins may serve as novel natural antioxidants for functional food ingredients and additives.