Supercritical and subcritical extraction of ursolic acid and polyphenols from apple pomace: Effect of variables on composition and antioxidant capacity

摘要

This research explores the effect of temperature, pressure, static time, dynamic time,co‐solvent, pretreatment, and particle size on the supercritical/subcritical extractionof ursolic acid (UA), polyphenols, and their antioxidant activity. Experiments werecontrolled by a screen‐out (Plackett–Burman) statistical methodology. From the results,it could be observed that similar conditions benefited the extraction of UA andpolyphenols. The highest yield of UA (6,117.2 μg/g) was obtained when ethanol (25%w/w), particle size (>250 μm), and temperature (60℃) were at their high boundaries.Phloridzin and epicatechin were identified as the most abundant polyphenols, showingconcentrations of 531.4 and 288.3 μg/g, respectively. A maximum oxygen radicalabsorbance capacity of 113.5 μmol TE/g and total polyphenolic capacity (TPC) of1.7 mg GAE/g were obtained. As a result, higher yields were strongly related to theeffect of variables on diffusion and solubility, leading to a more efficient and sustainableprocess.Practical applicationsThere is always a need to develop efficient and environmentally friendly extractionprocesses. It is well known that most of the conventional extraction methods are solventintensive, time‐consuming, and require multistep. Supercritical extraction hasdemonstrated to be a feasible nonconventional extraction method. However, beforescaling, it is essential to screen‐out critical variables among the set of variables available.The extraction of ursolic acid (UA) and polyphenol fractions from apple pomacehas the potential for their application in the food and pharmaceutical industry.The current research evaluates the effect of seven variables in the extraction of UA,polyphenols, and their antioxidant capacity from apple pomace. The information herepresented aids in understanding which variables are more important for the extractionprocess.