Combination Effects of Phosphate and NaCl on Physiochemical, Microbiological, and Sensory Properties of Frozen Nile Tilapia (Oreochromis niloticus) Fillets during Frozen Storage

The objective of this research was to investigate the combination effects of phosphate and sodium chloride (NaCl) on the quality of frozen Nile tilapia fillets (control and treated with sodium tripolyphosphate 1.4 % STPP + 2.7 % NaCl) during storage at -18 ºC for up to 8 months. Results showed that moisture content decreased slightly (P ≤ 0.05), while pH gradual decreased, total volatile base nitrogen (TVB-N) increased, and hardness and gumminess decreased with increasing time (P ≤ 0.05). Thiobarbituric acid-reactive substances (TBARS) values were low (0.01 - 0.03 mg malonaldehyde/kg) and phosphate content ranged from 3350 - 3900 mg/kg. There was no significant difference (P > 0.05) in drip loss during storage. The control had higher cooking losses and the L* value increased with increasing storage time, while a*, b*, C*, and h* values were not significantly different (P > 0.05). Appearance and texture acceptability scores of treated fish were significantly higher than the control throughout storage (P ≤ 0.05). Total aerobic psychrophilic and mesophilic bacteria were relatively unchanged at about 4 log CFU/g.