The effects of food container depth and coverage on the quality of superchilled rainbow trout




Magnea Karlsdóttir, Erwan Queguiner, Björn Margeirsson, Sigurjón Arason, Aðalheiður Ólafsdóttir

Supported by:

AVS R&D Fund (R 17 016-17), Technology Development Fund (164698-1061)


Sigurjón Arason

Chief Engineer

The effects of food container depth and coverage on the quality of superchilled rainbow trout

Fresh farmed fish is generally gutted and packed in a foam plastic box with ice for export in refrigerated containers. In view of the great development that has taken place in terms of supercooling and its positive effect on the quality of fish products, other more cost-effective and environmentally friendly packaging solutions have been examined, including insulated food containers. The main objective of the project was to evaluate the impact of different packaging methods on the quality of fresh rainbow trout. Gutted fish with a head was packed in a foam plastic box and insulated pots of different depths (29-60 cm). In addition to comparing different depths of pots, different embodiments of closing pots were also examined. Experimental fish were observed at the top and bottom of each tank. The pots were stored in a temperature-controlled environment at about -1 ° C and measurements were made after 8 and 13 days after packing. The fish packed in a foam box was either supercooled before packing or cooled in the traditional way with ice. This was done to assess the effect of supercooling on fresh rainbow trout. To assess the quality of the rainbow trout, microbial growth, texture and release in fillets were monitored. The results showed that the packaging solutions examined in the project had a relatively small effect on the total number of microorganisms, but there was no significant difference between experimental groups at the end of the storage period. In general, there was little to no difference between groups in texture and texture in fillets. On the other hand, the results showed that it is necessary to close the pots, but the type did not have a significant effect. Supercooling before packing had a significant effect on release. Fish that was cooled in the traditional way and packed in a foam plastic box with ice had significantly more release compared to when it was super-cooled and packed in a pot or foam plastic box without ice. The results show that there is no significant difference between foam boxes and pots of different depths compared to the quality variables examined in this project. They indicate that the transport of supercooled rainbow trout in pots is a viable option in terms of the stability of the raw material and the quality of the product.

The overall aim of the study was to explore the effects of different packaging solutions on the quality of fresh rainbow trout. Different packaging methods included expanded polystyrene boxes (EPS), insulated food containers of 29 to 60 cm depth with various combination of covers. Each container was split up into two groups, top- and bottom layer. Both fish chilled on ice and superchilled fish were considered. Microbial growth and sensory characteristics (fillet gaping, softness and elasticity) were used to evaluate the quality of the rainbow trout fillets after 8 and 13 days of storage at around -1 ° C. The different packaging solutions had no effects on the microbial quality of the fish. Moreover, no listeria activity was detected. Sensory evaluation showed minor differences between containers of different depths and / or EPS boxes, as well as between top and bottom layers. However, the presence of cover proved to be of great importance, but the type of cover turned out to be not relevant. The effects of superchilling before packaging on fillet gaping was evident in present study since fish packed in EPS box with ice resulted in more gaping than superchilled fish packed in EPS boxes and / or containers without ice.

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