Ultrasonication-driven optimization of cricket protein nanoemulsions: influence of pH and rheological stabilizers

Abstract

This study investigates the formulation of sustainable nanoemulsions using cricket protein as a natural emulsifier and linseed oil as the dispersed phase, emphasizing the effects of pH, ultrasonication, and rheological modifiers on emulsion stability and structure. Surface and interfacial tension analyses revealed significant reductions with increasing protein concentration, stabilizing at ≥1 g/L. At alkaline pH (≥12), interfacial tension became unmeasurable due to complete phase merging, attributed to enhanced protein solubility and surface activity. Droplet size distribution exhibited bimodal patterns across all pH levels, with the smallest Sauter diameter (0.54 μm) and optimal span (1.91) achieved at pH 12.5.

Ultrasonication parameters (amplitude and sonication time) were optimized using response surface methodology. The smallest droplet size (0.365 μm) was predicted at 63 % amplitude and 9.6 min of sonication. However, higher energy inputs also increased polydispersity, likely due to droplet recoalescence in the absence of sufficient emulsifier. To enhance stability, guar gum (GG) and advanced performance xanthan gum (APXG) were tested. APXG, particularly at ≥0.25 wt%, significantly improved viscoelasticity (G′ > G″) and increased consistency (K = 9.87 Pa·sⁿ at 0.5 wt%), forming gel-like structures and reducing the Turbiscan Stability Index (TSI) over a 21-day period.

These results underscore the critical roles of pH, ultrasonic processing, and rheological modification in designing robust nanoemulsions. The integration of cricket protein and APXG under optimized conditions offers a promising platform for stable, eco-friendly emulsions in functional food and nutraceutical applications.