Extraction of anthocyanins from Aronia melanocarpa skin waste as a sustainable source of natural colorants

Aronia melanocarpa (Michx.) Elliott (black chokeberry) skin wastes from the production of Aronia fruit juice were extracted using a batch extraction method and a novel integrated extraction‐adsorption process. Optimum conditions for batch extraction were as follows: 60 °C, 3 h, acid (0.1% v/v hydrochloric acid), biomass‐to‐solvent ratio of 1:16, and biomass‐to‐solid phase extraction resin ratio of 1:1. The integrated extraction‐adsorption process gave improved anthocyanin yields of higher quality when the process was performed for 3 h without cooling of the circulating liquid, and with a flow rate of 1.3 ml s−1. Overall, the new method showed better anthocyanin yield and purity compared with the batch method, increasing the extraction yield by ca. 20% (5.25→6.34 mg g−1 dry weight of pomace) and increasing anthocyanin content by ca. 40% (19.9%→28.4% w/w dry weight of extract). This method also simplified the process as three steps were eliminated saving time and energy. Furthermore, the integrated extraction‐adsorption method is industrially scalable to produce large quantities of anthocyanins. In the batch method, anthocyanins present in A. melanocarpa skins were identified as cyanidin‐3‐O‐galactoside (38.8%), cyanidin‐3‐O‐arabinoside (6.4%), cyanidin‐3‐O‐glucoside (3.6%), cyanidin‐3‐O‐xyloside (0.5%), and the cyanidin aglycon (50.7%); in the continuous method, anthocyanin content was cyanidin‐3‐O‐galactoside (45.7%), cyanidin‐3‐O‐arabinoside (16%), cyanidin‐3‐O‐glucoside (3.6%), cyanidin‐3‐O‐xyloside (2.7%), and the cyanidin aglycon (32%). The integrated extraction‐adsorption method was shown to be substantially less susceptible to acid‐catalysed anthocyanin decomposition processes. All anthocyanins were derived from only one anthocyanidin parent structure (cyanidin), and only monosaccharide glycosides were identified, which is unusual when compared with other berries that typically have more anthocyanidins and/or greater glycosylation diversity.