Supercritical CO2 extraction of allicin from garlic flakes: Screening and kinetic studies. http://dx.doi.org/10.1016/j.foodres.2011.10.021

Abstract

The nutraceutical industry is currently interested in obtaining garlic extracts using mild extraction processesto recover high levels of labile allicin. This work studied oleoresin yield and extraction selectivity for allicin inthe supercritical CO2 extraction of freeze-dried aqueous garlic homogenate as a function of sample conditioningand process conditions. Agglomeration phenomena, which is responsible for substrate lumps in packedbeds and flow channeling in the bed during extraction, was avoided by lowering sample moisture below31 g kg^-1 water/substrate, and/or process temperature below 65 °C. Oleoresin yield increased slightly withextraction pressure (15–45 MPa) and dramatically with process temperature (35–65 °C), but the concentrationof allicin in the extract decreased as the temperature increased. Thus, an optimal combination of intermediatetemperature and pressure was selected that allowed reasonably large yields (>=19 g kg^-1oleoresin/substrate) and extraction selectivities (>=75 mg kg^-1 allicin/oleoresin). Based on experimental results,a 4 h extraction process at 55 °C and 30 MPa using 55 kg kg^-1 CO2/substrate was recommended. Cumulativeextraction plots for oleoresin and allicin were successfully adjusted using a linear driving forcemass transfer model.