Extraction of apple seed oil by supercritical carbon dioxide at pressures up to 1300 bar

Abstract

This paper describes the extraction of apple seed oil using supercritical CO2 at pressures up to 1300 bar in a 0.5 L extraction plant. The extraction plant was designed in-house, built and commissioned to work up to 1390 bar. The goal of this work was to study seed oil extraction and solubility under ultra-high extraction pressures. Apple seeds were extracted using supercritical carbon dioxide at 300, 500, 750, 1000 and 1300 bar, and at temperatures of 316, 326 and 336 K. The apparent solubility at each condition was determined from the constant rate extraction period observed in the extraction experiments. Under ultra-high pressure (1300 bar) and moderate temperature (336 K) experimental conditions, the maximum solubility achieved was ∼191 g extract/kg CO2 compared with ∼10 g extract/kg CO2 at commonly used extraction pressures of 300 bar. Apple seed oil is a highly valued natural skincare ingredient. The oil composition was determined in terms of fatty acid profile, water, polyphenol, cyanogen and tocopherol content. The seed residue after extraction was also analyzed for polyphenol and cyanogen content and was examined by SEM to establish the effects of extraction on residual seed structure. Complete extraction of tocopherols occurred at high pressure (≥750 bar) and moderate extraction temperature (≤326 K). The levels of polyphenols and cyanogens in the extracted oil were negligible to extremely low. Low concentrations of cyanogens make the seed oil potentially suitable for human consumption. The seed residue contained a polyphenol-rich fraction that could be extracted by solvent extraction and used in other products.