Abstract
The recovery of phenolic compounds from the two main components of artichoke waste, the outer bracts and the stems, was investigated. The total polyphenol content, expressed as gallic acid equivalents (GAE) per g of dry weight, was 24.14 ± 0.73 mg GAE/g for bracts and 35.71 ± 1.65 mg GAE/g for stems. Different solvents, including acetone, ethanol, hexane, ethyl lactate, water and 50:50 ethanol–water mixture, were preliminarily screened for their extraction efficiency. Aqueous ethanol was the most effective solvent and was used to assess the effects of temperature (T = 40–60 °C), extraction time (E = 30 – 90 min) and liquid- to-solid ratio (R = 10 –30 mL g–1) on the extraction yields. Under the best conditions (T = 60 °C, E = 90min, R = 30 mL g–1), the amount of phenolics recovered from bracts and stems were 19.44 and 28.02 mgGAE/g, respectively. For both materials, E was the most influential factor, followed by T and R. Overall, the results obtained support the use of artichoke waste as a source of phenolic antioxidants and give useful directions on how to improve recovery by proper selection of extraction conditions.
