Melting point depression of solid lipids in pressurized carbon dioxide

• Melting point of the solid lipids decreased in pressurized carbon dioxide.
• Melting point of the lipids with shorter chain fatty acids decreased more.
• There is a positive correlation between volumetric expansion and melting point depression.
• Volumetric expansion can be used to compare melting point depression of lipids in carbon dioxide.

Understanding the melting behavior of solid lipids in pressurized carbon dioxide (CO2) is important for the production of solid lipid particles using supercritical CO2. Melting point depression and volumetric expansion of solid lipids in pressurized CO2 was studied as a function of pressure. The highest melting point depression (76.5%) was observed for coconut oil at 43 bar, whereas the lowest was for fully hydrogenated canola oil (18.5%) at 122 bar. The lipids composed of shorter chain fatty acids exhibited higher melting point depression. A positive correlation was observed between the melting point depression and volumetric expansion of the lipids. The lowest expansion was observed for fully hydrogenated canola oil (9.7%), whereas the highest was for lauric acid (42.7%) at the lowest pressure where the lipids melted. Supercritical CO2 technology can lead to energy savings in particle formation processes due to lower melting temperatures and also provide better protection of the bioactives in such potential delivery systems.

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