Application of response surface methodology for the optimization of pressurized liquid extraction of cherry pomace

In recent years, the sour cherry (Prunus cerasus L.) has been a very popular fruit in the world. Cherry consumption has a positive effect on prevention of cardiovascular, Alzheimer’s and inflammatory diseases, improves appetite, and lowers blood pressure. All these beneficial advantages of sour cherries are due to the high content of bioactives such as anthocyanins, polyphenols, and proanthocyanidins. Today, cherries are consumed as fresh fruits or used for the production of wine, juice, and jam; they can be dried or processed into other products. Cherry juice generates large amounts of pomace, most of which are currently discarded as waste. Therefore, there is an urgent need for cherry pomace valorisation studies for their conversion into ingredients of higher added value. The aim of this study was to optimise the pressurized liquid extraction process (PLE) to recover valuable polar fractions from cherry pomace residues after supercritical fluid extraction with carbon dioxide (SFECO2). A response surface methodology based on a central composite design was used to determine the effect of extraction time and temperature on the selected response factors. Total extraction yield, total phenolic content (TPC), ABTS radical scavenging activity, oxygen radical scavenging capacity (ORAC), and proanthocyanidins content were chosen as responses. The highest yield (29.61%) was obtained at the highest temperature and time (120 °C and 45 min), while the highest ABTS (125.42 mg TE g-1 of extract) and TPC (47.17 mg GAE g-1 of extract) were obtained at 60 °C and 30 min. The proanthocyanidins dominated in the extract obtained at 90 °C and 30 min. Taking into account all observed responses, the extraction process was optimised and validated. Therefore, the results obtained in this study may be promising for the recovery of bioactive compounds from defatted cherry pomace by PLE.