Evaluation of drip loss in injected fish fillet after freezing and thawing
Injection technologies have been widely used in the seafood industry to incorporate marinades and functional additives. Marinades have to be able to function in both fresh and frozen seafood. Many frozen seafoods can go through the freeze process at least twice. As a result, the objective of this project was to evaluate drip loss through two freeze and thaw cycles on an injected fish product. For this experiment, Arrowtooth flounder fillets (n=50) were collected from a local seafood processor. The fillets were separated by sides (top or bottom) and 2 groups of 10 fillets (5 top and 5 bottom) were selected for the experiment. For group 1 (treatment 1), the fillets were first brine injected and then subjected to 2 consecutive freeze and thaw cycles. However, for group 2 (treatment 2), the samples were first frozen and thawed prior to brine injected and then freeze and thawed again. Each fillet was brine injected with 3% sodium chloride (NaCl) and 3% sodium tripolyphosphate (SP) under identical conditions (injector pressure =1 bar , # needles = 50 , belt rate = 26 cycle/minutes). After each freezing cycle, each fillet was individually vacuum-packaged, stored at -25 ºC for 4 days and thawed at 4 ºC for 24 hours. Weights of each fillet were recorded at before freezing, before injection, 30 minutes after injection and after thawing. Injection percent and drip loss for each freezing-thawing cycle were calculated. Brine injection of fillets from the bottom ranged between 7.1-16.5% and fillets from the top ranged between 10.6-24.5% of initial weight. For treatment 1, there was no significant effect from either side or freeze cycle on drip loss. For treatment 2, there was significantly more drip loss after the 1st freezing than after the second. However, the overall drip loss from each treatment was not significantly different. Therefore, the sequence of brine injection and freezing cycle has no significant impact on total drip lost.