Quality changes in chilled Norway lobster (Nephrops norvegicus) tail meat and the effects of delayed icing

The quality deterioration of Norway lobster (Nephrops norvegicus) tail meat was monitored during ice storage. The K-value started at 0.7% and reached a value of 39.7% on day 14. Muscle pH followed a sigmoidal pattern that reached a plateau on day 6. Bacterial load and trimethylamine (TMA) increased only after a lag phase to reach considerable levels by day 14 (5.3 log cfu and 10.2 mg (100 g)(-1), respectively). These analytical data were compared with sensory data. Principal component analysis (PCA) indicated that laboratory measures were correlated positively with the smell strength of cooked product (increasingly strong) and negatively with the smell character of raw and cooked product (sour-ammoniacal in raw and neutral in cooked products), flavour and aftertaste (both increasingly bland-bitter). The effects of icing delays on the quality of tail meat were also evaluated. Changes in K-values, microbial load, muscle pH and TMA indicated that the delay to icing should be no more than 4 h (at 16 degrees C) to ensure that quality is not compromised during subsequent post-harvest storage.