Investigating a low-coolant-consumption and high-quality method for freezing tilapia fillets: Evaluation of suitable liquid coolants and the potential of immersion freezing as a moderate low-temperature alternative to liquid nitrogen freezing

This study aimed to evaluate the impact of −20 °C static air freezing (−20 °C-SAF), −35 °C blast air freezing (−35 °C-BAF), −30 °C immersion freezing (−30 °C-IF), and −80 °C liquid nitrogen freezing (−80 °C-LNF) on quality of tilapia fillets during 90-day storage period at −18 °C. Utilizing response surface methodology, an optimal formulation for composite coolants was established, comprising 20.00% ethanol, 10.19% propylene glycol, 8.00% NaCl, and 15.00% betaine. Key findings indicated that both −30 °C-IF and −80 °C-LNF methods significantly enhanced freezing rates, generated smaller and more uniformly distributed ice crystals, compared with −20 °C-SAF and -35 °C-BAF ( p < 0.05). During storage at −18 °C, both the −30 °C-IF and −80 °C-LNF treatments improved quality maintenance in comparison to conventional methods ( p < 0.05). Notably, the preservation outcomes achieved with −30 °C-IF were comparable to those obtained with −80 °C-LNF across most assessed quality indices ( p > 0.05), while simultaneously reducing the consumptionof freezing media. These finding position −30 °C-IF as a potentially cost-efficient alternative to premium quick-frozen tilapia products. • An optimal liquid coolant formulation was successfully developed for the immersion freezing of tilapia fillets. • The −30 °C-IF achieved the highest efficiency, marked by the shortest transit time through the zone of maximum ice crystal formation (Z-MICF), followed by −80 °C-LNF. • Both −30 °C-IF and −80 °C-LNF significantly outperformed −20 °C-SAF and −35 °C-BAF, with minimal quality differences observed between the two former methods. • The −30 °C-IF treatment produced the most refined ice crystal morphology, which effectively preserved the integrity of the muscle fibers. • Compared to −80 °C-LNF, the −30 °C-IF method presents a significant advantage in terms of potential cost efficiency.