The Influence of Strategic Freezing and Thawing Protocols on Soybean Protein Isolate Emulsion Gel Fat Substitutes: Freeze‐Thaw Stability and Structural Integrity

This study addresses this critical technological challenge by systematically evaluating the impact of slow freezing or liquid nitrogen quick-freezing, and thawing method of microwave, or 37°C/25°C water bath, or 4°C refrigeration, on the freeze-thaw stability of soybean protein isolate (SPI)-based emulsion gel fat substitutes. The results demonstrated that quick-freezing effectively preserved the microstructure by forming smaller and more uniform ice crystals, thereby maintaining superior water-holding capacity, textural properties (hardness and chewiness), and thermal stability compared to slow freezing. Among thawing methods, 37°C water-bath thawing was identified as the optimal approach, minimizing drip loss and microstructural damage (average pore size: 35.13 ± 17.52 µm), closely resembling fresh samples (31.73 ± 5.85 µm), and showing significantly less damage caused by slow freezing-thawing (90.21 ± 64.56 µm). The study deciphers the underlying mechanisms of quality degradation, linking ice crystal morphology to the disruption of the gel network structure. This work provides a practical strategy to enhance freeze-thaw stability by deciphering its underlying mechanism in plant-based fat substitutes, offering crucial insights for improving frozen plant-based food quality. PRACTICAL APPLICATIONS: Enhanced freeze-thaw stability addresses a key challenge for fat substitutes. Clarified the mechanism of ice crystal-induced structural damage. Identified quick-freezing with 37°C thawing as the optimal strategy. Provided a practical solution to improve frozen plant-based food quality.