Evaluation of Three Green Extraction Methods of Anthocyanins and Other Polyphenolic Compounds from Ribes nigrum

This study evaluated three green extraction methods—accelerated solvent extraction (ASE), ultrasound-assisted extraction (UAE), and laser irradiation extraction (LIE)—for the recovery of anthocyanins, anthocyanidins, and other polyphenolic compounds from Ribes nigrum fruits. We analyzed phenolic, flavonoid, and anthocyanin contents spectrophotometrically and by HPLC-DAD (High-Performance Liquid Chromatography with a Diode-Array Detector). Acidified ethyl alcohol substantially increased extraction of anthocyanins, anthocyanidins, and other polyphenolic compounds across all techniques. ASE at 100 °C was the most effective method for targeted compounds from R. nigrum in acidified ethyl alcohol (1.215 ± 0.09 mg/mL chlorogenic acid equivalent for total polyphenols and 50.273 ± 4.3 µg/mL rutin equivalent for flavonoid content) compared with the other two methods. LIE at 1550 nm, using acidified ethyl alcohol as the solvent, yielded higher levels of polyphenolic compounds, whereas flavonoid content was only weakly affected by the laser wavelength. The dominant polyphenolic compounds were catechin, epicatechin, chlorogenic acid, and rutin; delphinidin-3-glucoside was the predominant anthocyanin, and delphinidin was the predominant anthocyanidin. All R. nigrum fruit extracts reduced ferric ion (Fe3+) to ferrous ion (Fe2+) more effectively than they scavenged free radicals. The results indicate that the green extraction methods studied represent a viable and efficient means of producing high-value, polyphenolic-rich extracts.