Central composite design of pressurised hot water extraction process for extracting capsaicinoids from chili peppers

Pressurised hot water extraction (PHWE) was applied to chilies in order to optimise extraction yield of capsaicinoids (capsaicin, dihydrocapsaicin, nordihydrocapsaicin, nonivamide). Determination of the optimum extraction procedure was performed by comparison of the yield of the extracts. Capsaicinoids content was determined by HPLC coupled with mass spectrometry. An optimisation study was performed using water as an extraction solvent at constant extraction pressure (20 MPa), extraction temperature ranging from 120 to 240 °C and static extraction time ranging from 5 to 60 min as independent variables. The optimum PHWE conditions for all response variables were estimated; however, PHWE conditions resulting in the highest recovery of capsaicinoids (20 MPa, 200 °C and 10 + 20 min of static extraction time) were chosen for comparison with a conventional Soxhlet extraction (SOX) in the case of seven chili pepper fruit samples (chili peppers of species Capsicum chinenses: Trinidad Scorpion Moruga, Jamaican Hot Red, and Yellow Habanero, chilies of species Capsicum annuum: Yellow Bedder, Ring of Fire, and Chiltepin, chili pepper Tabasco of species Capsicum frutescens) and three chili spices (ground spices from Trinidad Scorpion Moruga, Bhut Jolokia, and Fatalii Red, all of species Capsicum chinenses).