Ultrasonicated brine: implications for polyphosphate functionality and beef quality

This study evaluated whether ultrasonication of brining solutions can enhance the functional effectiveness of polyphosphate in beef systems, thereby providing a technological basis for reducing phosphate dependency. A 1.5% (w/v) NaCl brine was ultrasonicated using probe ultrasound (20 kHz, 300 W) for 0, 15, or 30 min either before polyphosphate addition (UBP) or after polyphosphate addition (UAP). Sodium tripolyphosphate was incorporated at 0, 0.1, or 0.2% (w/v), and brines were mixed with ground Longissimus lumborum at a 1:1 (w/v) ratio. Brine pH and redox potential were measured, and meat pH, water-holding capacity (WHC), cooking loss, emulsifying activity and stability, interfacial protein concentration, and color parameters were evaluated. Polyphosphate concentration was the dominant factor influencing meat pH, WHC, cooking loss, and emulsifying properties. Brine ultrasonication significantly modulated these effects, particularly through interactions with polyphosphate concentration. Pre-sonication of brine followed by polyphosphate addition (UBP) consistently resulted in higher WHC, lower cooking loss, and improved emulsifying activity compared with non-sonicated brine at the same phosphate levels. In contrast, ultrasonication of phosphate-containing brine (UAP) showed limited or inconsistent benefits at low phosphate concentrations. Structural and spectroscopic analyses (FESEM and FTIR) revealed that ultrasonicated brine promoted protein unfolding and formation of a denser, more cohesive protein network, consistent with improved water retention and thermal stability. Overall, the results demonstrate that ultrasonicated brine acts as a process-level enhancer that intensifies the functional performance of polyphosphate. While increasing phosphate concentration continuously improved meat quality, brine ultrasonication-particularly when applied prior to phosphate addition-amplified these effects, supporting the feasibility of achieving comparable functionality at lower phosphate inputs.