Heat-drying and size reduction-treated tapioca flour stabilized oil-in-water emulsion-loaded eugenol: Physical properties, stability, and in vitro gastrointestinal digestion

Abstract

Native tapioca is strongly hydrophilic and hence not surface active in an emulsion. This research improved the functional properties of tapioca flour using physical modifications as heat-drying (HD) and combined heat-drying and ball milling (HD-Bmill) to act as a particle stabilizer in Pickering oil-in-water emulsions. The modified tapioca flour-stabilized emulsion was used to encapsulate eugenol (oil-soluble bioactive compound), and eugenol stabilities during storage and in vitro gastrointestinal digestion were investigated. Results showed that the HD and HD-Bmill treatments changed the morphology and physicochemical properties of the tapioca flour, especially by increasing the hydrophobicity and emulsifying ability, expressed as surface activity on the oil droplet surface. The HD and HD-Bmill-stabilized emulsion-loaded eugenol enhanced eugenol encapsulation efficiency (EE) compared to the control emulsion (without flour) and the emulsion containing native flour, resulting in higher antioxidant activity. The HD and HD-Bmill flours improved eugenol stability during storage at room temperature for 14 days compared to native flour. After the eugenol-loaded emulsions had passed through in vitro gastrointestinal digestion, the HD and HD-Bmill flours increased the release of free fatty acids, indicating an increase in lipid digestibility compared to native flour. The HD-Bmill flour also improved eugenol stability during digestion compared to native flour. HD-Bmill flour showed promise as an alternative non-chemical particle stabilizer for applications in functional emulsion foods that encapsulate oil-soluble bioactive compounds.

Keywords

• Heat-drying
• Tapioca flour
• Emulsion
• Particle stabilizers
• Encapsulation
• Eugenol