Extraction and Chemical Characterization of Functional Phenols and Proteins from Coffee (Coffea arabica) By-Products
Barbara Prandi, Maura Ferri, Stefania Monari, C. Zurlini, Ilaria Maria Cigognini, Stefanie Verstringe, Dennis Schaller, Martha Walter, Luciano Navarini, Annalisa Tassoni, Stefano Sforza, Tullia Tedeschi
Abstract
Not all the coffee produced goes to the roasting stage, because non-compliant green coffee beans are usually discarded by roasters and the silverskin of the coffee is usually removed and discarded. In the present work, non-compliant green coffee beans and coffee silverskins were fully characterized from a chemical point of view. In addition, enzyme-assisted extraction was applied to recover a fraction rich in proteins and polyphenols, tested for antimicrobial, antityrosinase, and antioxidant activities. Non-compliant green coffee beans showed higher amounts of polyphenols, flavanols, flavonoids, and caffeine than coffee silverskins (which were richer in tannins). The enzymatic extraction of non-compliant coffee green beans produced extracts with a good protein content and with a consistent quantity of polyphenols. The extract showed antioxidant, antityrosinase, and antimicrobial activity, thus representing a promising strategy to recover defective green coffee beans. The antioxidant and antimicrobial activity of coffee silver skins is lower than that of non-compliant coffee green beans extracts, while the antityrosinase activity is comparable.