Effect of low-energy stirring temperature on the formation of oil-in-water emulsions stabilized by gelatin-arginine complexes

Abstract

The impact of low-energy stirring temperatures (30 °C, 50 °C, 70 °C, 90 °C) on the stability of gelatin emulsions was investigated when stirring with a magnetic stirrer at 1600 rpm for 3.5 h at an arginine (Arg) concentration of 1.2 % (w/v). The results indicated that as the stirring temperature increased, the appearance of the emulsions became more transparent and clearer, and their particle sizes and the absolute zeta potential values decreased significantly (P < 0.05). Moreover, the addition of Arg significantly enhanced the stability of the emulsions, with those prepared at 30 °C exhibiting the highest stability. These findings could be attributed to the fact that under the stirring temperature of 30 °C and in the presence of Arg, the depolymerization of gelatin increased, leading to a significant increase in the hydrophobic β-sheet structures (P < 0.05), which in turn resulted in a significant increase in the exposure of hydrophobic amino acids and negatively charged residues on the gelatin surface (P < 0.05). Ultimately, the stability of gelatin emulsions (φ = 5 %), prepared via this one-step stirring method, was significantly improved. The information gathered could provide guidance on preparing protein-stabilized emulsions with low oil phase volume fractions using low-energy emulsification techniques.

Keywords: Gelatin; Low-energy emulsification; Secondary structure; Surface tension; Thermal stability of emulsion.