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 (–35 o C) and stored at –25 o C 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