Characterization of methyltetrahydrophthalic anhydride esterified corn starch and their ability in stabilizing Pickering emulsion

Methyltetrahydrophthalic anhydride (MeTHPA) esterified corn starches (MeCS) with degrees of substitution (DS) of 0.0066-0.072 were prepared, characterized and applied to stabilize Pickering emulsion. Fourier transform infrared spectroscopy analysis revealed the presence of a new ester group in MeCS. MeTHPA modification damaged the crystal structure of the corn starch, made its surface structure rough and irregular, and increased its contact angle. These changes were positively correlated with the DS of MeCS. Compared to native corn starch, the particle size of MeCS increased first and then decreased with an increase in DS, the lowest value (4.67 +/- 0.08 mu m) was observed for MeCS with highest DS (0.072). The stability of Pickering emulsions stabilized by MeCS with a DS of 0.072 was better than those stabilized by MeCS with lower DS (0.0066-0.019), which may attribute to their smaller particle size and higher viscosity. MeCS (DS 0.072) as emulsifiers at a concentration of 3% (w/v) could keep the emulsion stable even after 50 days of storage. This research suggested that MeCS at proper DS and concentration levels may serve as effective particle stabilizers for Pickering emulsions.

Automated summary

Methyltetrahydrophthalic anhydride (MeTHPA) esterified corn starches (MeCS) with degrees of substitution (DS) ranging from 0.0066 to 0.072 were prepared and found to be effective in stabilizing Pickering emulsion. The modification of MeTHPA damaged the crystal structure of corn starch, roughened its surface structure, and increased its contact angle, which were positively correlated with the DS of MeCS. The particle size of MeCS increased and then decreased with increasing DS, with the smallest size observed for MeCS with a DS of 0.072. The Pickering emulsions stabilized by MeCS with a DS of 0.072 exhibited better stability compared to those stabilized by MeCS with lower DS, which can be attributed to their smaller particle size and higher viscosity. MeCS with a DS of 0.072, at a concentration of 3% (w/v), could maintain emulsion stability even after 50 days of storage. These findings suggest that MeCS with appropriate DS and concentration levels could be effective particle stabilizers for Pickering emulsions.