Replacing Sodium Tripolyphosphate in Frozen Shrimp Preservation: Soaking Treatments, Nonthermal Technologies, and Their Limitations

Shrimp's nutrient-rich composition and high water activity make it highly perishable, necessitating effective preservation methods like freezing. However, freezing induces undesirable changes, including protein denaturation, lipid oxidation, and reductions in water-holding capacity (WHC), yield, and textural quality. Sodium tripolyphosphate (STPP) is traditionally used to mitigate these effects due to its ability to stabilize proteins, enhance pH and ionic strength, and inhibit oxidation. Yet, STPP presents significant health, environmental, and regulatory challenges, prompting growing interest in sustainable alternatives. This review critically evaluates the effectiveness of STPP and its substitutes, including alkali metal compounds, polysaccharides, proteins, and their combinations. Each class exhibits distinct mechanisms such as ionic strength modulation, hydrogen bonding, and antioxidative activity to preserve shrimp muscle integrity. In addition, nonthermal technologies like ultrasound, vacuum tumbling, high-pressure processing, pulsed electric field, and cold plasma show promise in improving soaking efficiency, structural retention, and oxidative stability. These technologies can enhance or complement the effects of soaking agents through physical, chemical, and enzymatic pathways. Despite promising results, challenges remain regarding the scalability, cost, sodium content, soaking durations, and limited shrimp-specific validation of many treatments. Current findings highlight the need for optimized, clean-label cryoprotective strategies that align with health regulations, environmental goals, and consumer preferences. Future efforts should focus on integrating effective compound combinations with advanced technologies to develop robust, industry-ready solutions that ensure both product quality and sustainability in frozen shrimp processing.