EFFECT OF MODIFIED ATMOSPHERE PACKAGING ON SHELF-LIFE OF ICED FRESH HAKE SLICES

Shelf-life of hake slices (Merluccius merluccius) stored in the ice st ate (2 +/- 1 degrees C) under modified atmosphere packaging (MAP) cond itions was determined by measurements of pH, total volatile bases (TVB ) and trimethylamine (TMA) content, mesophilic and psychrophilic bacte rial counts, malonaldehyde content, exudation, protein functionality a nd sensorial analyses (colour and odour). The effect of different gas mixtures were evaluated: (1) 40% CO2, 50% N-2, 10% O-2;(2) 60% CO2, 30 % N-2, 10% O-2; (3) 40% CO2, 30% N-2, 30% O-2;(4) 60% CO2, 10% N-2, 30 % O-2 and (5) air (control). Important differences were found between MAP-stored and air-stored bake slices. Shelf-life of hake stored under MAP conditions was two-fold extended. Bacterial growth was inhibited, increases of pH, TMA and TVB were reduced, and alterations in protein functionality were delayed, and off-odours were not noted in MAP-stor ed hake slices after 21 days storage. Significant correlations were fo und between TMA content and total viable count (TVC), as well as betwe en apparent viscosity and exudation. Hake slices could be stored in th e ice state under MAP conditions for about three weeks without an impo rtant loss of quality. Fish freshness, handling practices and initial bacterial load have an important influence of shelf-life of hake.