Optimization of high pressure extraction processes for the separation of raspberry pomace into lipophilic and hydrophilic fractions

Abstract

Berry juice production residues are used inefficiently and in many cases are wasted, due to a lack of valorization of their processing methods. This study provides an example of biorefining of raspberry pomace by using high pressure extraction. Lipophilic fractions were isolated by pressurized liquid extraction (PLE) with hexane or supercritical carbon dioxide extraction (SFE-CO2), while the residues were re-extracted with polar solvents, methanol or ethanol. Optimal parameters were established by Central Composite Design and Response Surface Methodology. The yields of lipophilic and hydrophilic fractions were up to 15 and 25%, respectively. Antioxidant properties of extracts were evaluated by total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC). Polar fractions were remarkably stronger antioxidants, e.g. TPC of hexane and methanol extracts were 5.37–10.15 and 26.31–38.95mg/g gallic acid equivalents, respectively. Raspberry pomace extracts may be promising ingredients for functional foods, nutraceuticals, cosmetics and other applications.