Supercritical CO2 extraction of spices: A systematic study with focus on terpenes and piperamides from black pepper (Piper nigrum L.)

Black pepper (P. nigrum L.) is considered one of the most valuable spices and a promising candidate in natural product research. In this study, the influence of different combinations of pressures (100-300 bar) and temperatures (40-60 °C) on the supercritical CO2 (SC-CO2) recovery of several key compounds from black pepper was evaluated systematically. The extraction curves showed that terpenes were recovered in a short time under all studied conditions. In contrast, higher pressure values were required to extract piperamides efficiently. Furthermore, the differences in the extraction kinetics of piperine, piperettine, pellitorine, guineensine, and N-isobutyl-2,4,14-eicosatrienamide were linked with several structural features, such as the nature of the amine group or the terminal part of the fatty acid. The data from the isocratic experiments represented the starting point for designing a two-step pressure gradient SC-CO2 process in which one terpene-rich and one piperamide-rich product were successively obtained.