Effect of temperature, pH, and ionic strength on the structure and physical stability of double emulsions prepared with starch

To developed stable double emulsions (DEs) that were resistant to environmental stress, native corn starch (NCS) or high-amylose starch was used as material to prepare starch-based double emulsions (SDEs). The effects of temperature (4–60 °C, pH 7.0, 0 mmol/L NaCl), pH (2.0–8.0, 25 °C, 0 mmol/L NaCl), and NaCl concentration (10–100 mmol/L, 25 °C, pH 7.0) on the droplet size distribution, particle size, microstructure, interfacial rheology, and interfacial tension of the SDEs were evaluated. Results revealed that DEs stabilized by NCS of 7 g/100 mL concentration (7% NCS DEs) had the small mean particle size (4.80 ± 0.56 μm) with type-A structure, a high elasticity (14.98 Pa) and toughness (132.85 Pa) interfacial film. Moreover, the relationship between the different SDEs structures and their physical stability confirmed that 7%NCS DE exhibited excellent physical stability and was resistant to heat, acid and alkali conditions, and salt, owing to their dense network structure (Tanδ<1) and stable interfacial tension (39.85 ± 0.03 mN/m). This study demonstrates the potential of SDEs provides new practical applications.