The effect of glaze on the quality of frozen stored Alaska pollack (Theragra chalcogramma) fillets under stable and unstable conditions

Abstract

Frozen fillets (n = 288) of Alaska pollack (Theragra chalcogramma) were used to evaluate the effect of glaze on lipid oxidation and microbiological indicators during 6 months of freezing storage under stable (−18 °C) and unstable temperature (varying from −5 to −18 °C) conditions. The amount of glaze, moisture, fat and protein content were measured. Despite the low fat content in Alaska pollack, a positive effect of glazing and stable freezing conditions of storage on the range of oxidative changes of lipids expressed as thiobarbituric acid reactive substances was found. Total counts of viable cells slightly rose before the end of the storage period in both groups with commercially glazed fish. The average counts of psychrotrophs in each group () were at the same level, ranging from 9.1 ×103CFU·g-1to 1.1 × 104CFU·g-1. According to the microbiological results fillets stored under unstable conditions were considered to be acceptable, but sensory evaluation showed that at the end of frozen storage they could not be consumed because of rancidity. Based on our results, glaze application ranged from 10 to 15% guarantee of final quality, however, prevention of temperature fluctuation during storage is important to keep the quality of the frozen fillets. This is the first similar study in Alaska pollack.