Comparison of methods of extraction of phenolic compounds from American cranberry (Vaccinium macrocarpon L.) press residues
University of Latvia, 19 Raina Blvd., LV–1586, Riga, Latvia
*Correspondence: maris.klavins@lu.lv
Abstract:
American cranberries (Vaccinium macrocarpon L.) contain significant quantities of
various phenolic compounds. Most of these compounds are recovered when berry juice is
produced. However, a considerable part of polyphenols remain in berry press residues and are
discarded as food industry waste. The aim of the study was to compare the methods of extraction
of polyphenols (ultrasound, microwave-assisted, Soxhlet) from press residues of American
cranberry. The impact of main extraction parameters (e.g., extraction time, solid/solvent ratio,
solvent type) on the yield of extracted polyphenols. Ultrasound-assisted extraction showed the
highest potential from all studied methods, given its fast, convenient use and low cost. Aqueous
ethanol and methanol in the presence of acid (anthocyanin extractions should be assisted with
trifluoroacetic acid, polyphenol extractions – with HCl) were assessed as the best solvents for
extraction. The obtained extracts were characterised using the Folin-Ciocaulteu method for
determination of total phenolics and the pH-differential method for determination of total
anthocyanins, and UPLC–PDA was used to determine the content of individual anthocyanins.
Cyanidin-3-O-arabinoside, peonidin-3-O-galactoside, peonidin-3-O-glucoside and peonidin-3-
O-arabinoside were identified as the main anthocyanins in cranberry press residue extracts.
Key words:
anthocyanins, antioxidant activity, flavonoids, phenolic compounds, press residues, Vaccinium macrocarpon