Preparation of high freeze-thaw stable wheat gluten-based emulsions by incorporated deep eutectic solvents

Controlling crystallization of water phase and interfacial engineering is an effective strategy for improving freeze-thaw stability of protein-based emulsions. In this study, we prepared high freeze-thaw stability of wheat gluten (WG)-based emulsions by incorporated deep eutectic solvents (DES). Low melting point DES (−32.76 °C) with glycerol/choline chloride molar ratio of 2:1 were firstly achieved, and then water-diluted DES as solvent to dissolve WG, which was used to prepare emulsions. The results of interfacial property, confocal laser scanning microscopy (CLSM), and rheology showed that with increasing DES concentrations, WG exhibited thick interfacial membranes surrounding dispersed droplets, positively reflected in forming elastic gel-like emulsion with smaller droplet size. The freeze-thaw stability was characterized by monitoring the changes in their emulsion droplet size, stability against coalescence, as well as microstructure and thermal events. Higher concentrations of glycerol-based DES as “cryoprotectants agents” in the bulk phase and strong interfacial network of WG could prevent formation of the ice crystals and damage to the interface during the freezing process, resulting in formation of freeze-thaw stable emulsions even after three cycles of treatment (−40 °C, 24 h; 25 °C, 2 h). This finding provides a novel technical platform for the development and application of protein-based emulsions in frozen foods.