Effects of glazing, packaging and phosphate treatments on drip loss in rainbow trout (Oncorhynchus mykiss W.,1792) during frozen storage

Abstract

Fresh rainbow trout (Oncorhynchus mykiss W., 1792) were frozen with different pre-freezing treatments in an air blast freezer (–35oC) and stored at –25oC for 12 months. The treatments were done using 10% sodium polyphosphate and 3% sodium metaphosphate with 4% NaCl solutions and glazing packaging to prevent drip loss in the frozen fish. The effect of glazing packaging treatment on drip loss during frozen storage was significant (p<0.05) but none of the other treatments were effective (p>0.05). In other words, neither phosphate usage nor glazing treatment was effective when used by itself to prevent drip loss in the frozen rainbow trout. However, the combination of glazing packaging did prevent drip loss and protect the moisture content of the inner and surface layers of the product. In addition, the effect of gutting during the pre-freezing stage on drip loss during frozen storage was not significant.