Preparation of Chlorophyll-free Young Barley Leaf Extract Powders Using Supercritical Carbon Dioxide Modified with Cosolvent

In this study, we attempted to prepare chlorophyll-free young barley leaf extract powders using three different supercritical carbon dioxide (SCCO₂) drying processes. The pure SCCO₂ drying process for a methanolic extract solution resulted in a ~30% increase in the antioxidant (saponarin and isovitexin) content and a ~75% decrease in the chlorophyll content compared to a solvent evaporation method. The drying process with ethanol-modified SCCO₂ increased the antioxidant content considerably and completely removed the chlorophylls. However, this process could not dry an aqueous ethanolic extract solution with a more than 30% water content. The ethanol-modified SCCO₂ drying process that employed a periodic flush with pure SCCO₂ was found to effectively dry an aqueous ethanolic extract solution with more than 30% water content.