Comparative impact of pH-shifting and heat treatment on the structural and emulsifying properties of Clanis bilineata tsingtauica larvae protein.

This study investigated the individual and synergistic effects of pH-shifting (pH 2.0, 7.0, and 12.0) and heat treatment (25-90 °C) on the structural, physicochemical, and emulsifying properties of Clanis bilineata tsingtauica larvae protein (CBTLP). Results demonstrated that alkaline-shifting (pH 12.0) at ambient temperature (25 °C) is a highly efficient modification strategy, achieving an emulsifying activity index (EAI) of approximately 90 m2/g and solubility exceeding 80%, which is comparable to the functional levels of acid-shifting (pH 2.0) combined with 90 °C heating (EAI: 85 m2/g; solubility: 86.2%). However, the two treatments showed contrasting heat responses: pH 12.0-shifted samples exhibited high sensitivity to heat, with EAI dropping to 28 m2/g and droplet size expanding from 4.92 μm to 26.52 μm upon heating to 90 °C due to excessive hydrophobic aggregation. Conversely, pH 2.0-shifted CBTLP displayed progressive structural refinement and heat resilience, with EAI rising from 18 m2/g (25 °C) to 85 m2/g (90 °C) and droplet size refining to 7.01 μm. Structural analysis confirmed that while pH 12.0 induced immediate unfolding, the synergistic "acid + heat" treatment promoted controlled structural reorganization into a densified, micro-porous network. These findings provide a quantitative basis for selecting modification routes: alkaline-shifting for low-energy cold-processing and acid-shifting for heat-stabilized applications.