CO2-defatted oats: Solubility, emulsification and foaming properties

• SC-CO2 defatted oats (CO2-oats) had high levels of water-soluble protein.
• CO2-oats also had good foaming properties.
• CO2-oats had good emulsification properties at pH 10.5, especially with 0.1% NaCl.
• CO2-oats appeared as a promising raw material for liquid oat food applications.

Functional properties of conventional oat materials are relatively poor with respect to foam and emulsion formation and stabilization. This is largely due to the poor solubility of oat proteins and the presence of lipids in aqueous extracts of oats. In the experimental part of this study, extracts were prepared from different type oat flours (oat endosperm flour, oat fine flour, CO2-defatted whole oat flour and CO2-defatted oat flour) with a buffered aqueous extraction procedure at acidic (pH 4.5 and 6.5) and basic (pH 8.5 and 10.5) regions. The solubility of proteins was the highest at pH 10.5 and NaCl concentration of 2%. Among the extracts, CO2-oat flour showed improved foaming and emulsifying properties at basic pH values. The presence of 0.1% NaCl resulted in the lowest foam volumes, but the emulsion activity and stability values being the highest. Sucrose addition resulted in increased foam and emulsion stability of suspensions. Heat treatment at 80 °C impaired foam properties, whereas the stability of emulsions increased with the increase in temperature from 20 °C to 80 °C. CO2-extracted oats can be useful raw materials in beverages and other aqueous applications where protein functionality plays an important role.