Comparison of acetals as in situ modifiers for the supercritical fluid extraction of β-carotene from paprika with carbon dioxide

This study investigated various acetals for the purpose of improving the supercritical fluid extraction (SFE) using carbon dioxide of beta-carotene from an aqueous matrix. Results showed that the presence of water decreases the extraction efficiency of beta-carotene from paprika by a factor of 2. Upon the addition of 2,2-dimethoxypropane (DMP), the extraction efficiency of beta-carotene from wet paprika was increased by a factor of about 2.5 and from dry paprika a factor of 1.5. Diethoxypropane (DEP) and triethylorthoformate (TEOF) proved to be less effective for improving the extraction of beta-carotene from paprika. Although the addition of an acid catalyst enhances the reaction between DMP or TEOF with water under SFE conditions, an actual decrease in the extraction of carotene from paprika was found. It is possible, even without an acid catalyst, that DMP can remove a little water, improving extraction efficiency. However, its main impact on improving SFE seems to be as a modifier.