Policosanols from grape marc: A new step towards a sustainable biorefinery for the wine industry by SC-CO2 extraction

Supercritical carbon dioxide (SC-CO2) extraction of policosanol (PC) from grape marc was investigated for the first time. Employing the broken plus intact cells (BIC) model (Sovová's model) the investigation focused on analyzing the SC-CO2 process to extract the nonpolar fraction from grape marc efficiently. Operating conditions for SC-CO2 extraction—280 bar pressure, 70 °C temperature, and a flow rate of 10 kgCO2/h—yielded the highest policosanol content. The extracted policosanol ranged between 3922 and 4083 mg/kgDM, constituting approximately 8 % of the total extraction yield. Surprisingly, this amount of PC was of the same order of magnitude found in beeswax yellow, a well-known rich natural source of PC. The primary aliphatic alcohols found in the PC from grape marc were hexacosanol, octacosanol, and triacontanol. These findings were consistent with grape marc samples from other Italian regions. Furthermore, a comparative analysis between SC-CO2 and Soxhlet extraction methods for PC was carried out.