Impact of Various Pre-freezing Treatments on Drip Loss of Tilapia (Oreochromis niloticus) Fillets during Long-Term Storage at -18 °C

Abstract

The present study focused on studying the effects of different pre-treatments and freezing schedules on the drip-loss kinetics of Oreochromis niloticus fillets stored at -18 oC for 120 days. Drip-loss is an important quality parameter in frozen fish products since it negatively influences textural properties, flavour and nutritional content. In this research, four experimental conditions were applied: (T1) control group including untreated fillets, (T2) fillets pretreated with NaCl and STPP (sodium tripolyphosphate) followed by individual quick freezing (IQF), (T3) fillets pretreated with NaCl and STPP and an intermediate blanching step before IQF and (T4) fillets treated with NaCl and STPP and then blast frozen. Results showed that there was a statistically significant increase in drip-loss for all treatment groups over time spent in storage. However, the treatment of NaCl and STPP before freezing coupled with the blast freezing method resulted in the lowest drip-loss value (1.408%) at the end of 120 days while fillets treated with NaCl, STPP, and blanching recorded a significantly higher value (7.753%). Significant inter-group differences were observed by statistical comparison, thus confirming the greater effectiveness of blast freezing in maintaining water-holding capacity and reducing nutrient losses. The combined action of NaCl and phosphate has been shown to elevate the water-holding capacity (WHC) and cooking yield. Nevertheless, excessive use of phosphate can lead to undesirable effects such as a slimy texture, translucent appearance, and a soapy flavor (Rattanasatheirn et al., 2008), and may also result in phosphate residues exceeding legal limits in the final product. These findings have significant implications for the seafood industry, providing empirical-based solutions in order to increase shelf-life, enhance textural attributes, and retain nutritional quality of frozen tilapia fillets. Therefore, the present study contributes to the existing knowledge in the field of freezing technologies, particularly with respect to the preservation of the product quality in the domestic and the international market. The results obtained in this research can be used to guide further research and industrial processes related to the development of the quality of frozen fish products and improved acceptance by consumers.