Study on the stability of HIPEs stabilized by lotus root powder/whey protein and their application as fat substitute in fish cake

Developing natural fat replacers with excellent processing stability remains a challenge for the low-fat reformulation of surimi products. This study aimed to fabricate high internal phase emulsions (HIPEs) stabilized by lotus root powder/whey protein (LR/WP) composite particles, evaluate their salt and thermal stability, and explore their application as fat replacers in low-fat fish cakes. The LR/WP-stabilized HIPEs maintained stable particle size (below 23 μm) and zeta potential (−28 to −43 mV) under salt (0∼400 mM NaCl) and thermal (4∼100 °C) treatments, with all turbidity stability index (TSI) values remaining below 1.5, demonstrating superior stability under a wide range of ionic strengths and temperatures. Furthermore, replacing pork fat with HIPEs (25%∼100%) significantly enhanced the whiteness, hardness, springiness and chewiness of fish cakes. Meanwhile, HIPEs substitution improved the sensory flavor of fish cakes by boosting umami taste, reduced sour and astringent sensations, masked undesirable flavors, and enriched characteristic volatile aromas. In addition, HIPEs also enhanced the water-holding capacity of surimi gel by converting free water into immobile water. Rheological and microstructural results confirmed that all gels exhibited elasticity-dominated behavior (G' > G''), and the uniform filling of HIPEs strengthened hydrophobic interactions and disulfide cross-linking of surimi protein, promoting the formation of compact and homogeneous gel networks. This study provided a facile strategy to fabricate dual salt/thermo-stable HIPEs from LR/WP composite, and validated their potential as fat substitutes, offering a theoretical basis and technical support for the development of high-quality low-fat surimi products.