Contact
Aðalheiður Ólafsdóttir
Sensory evaluation manager
adalheiduro@matis.is
Effect of superchilled processing of whole whitefish - pre ‐ rigor / Effect of supercooling on spoilage processes and shelf life of whole fish and fillets
The aim of the experiment was to investigate the effect of supercooling on the damage processes and shelf life of whole fish and fillets. A study was carried out on whole supercooled cod soon after fishing and also on the effect of supercooling on fillets made from supercooled cod and cod cooled in ice in the traditional way. Temperature measurements, sensory evaluation, chemical and microbial measurements were used to compare the following experimental groups, which were stored at –1.4 to –1.2 ° C average temperature:
1) NC: whole cod cooled in ice
2) SC: supercooled whole cod
3) NC-NC: traditional fillet processing from whole cod cooled in ice
4) NC ‐ SC: super-chilled fillets made from whole cod cooled in ice
5) SC-NC: traditional fillet processing from super-chilled whole cod
6) SC-SC: super-chilled fillets made from super-chilled whole cod
Sensory evaluation results suggest that supercooled processing of whole cod can extend its shelf life by two days. Supercooling of whole cod did not affect the acidity, water content, water resistance and microbial growth of whole fish compared to fish that were not supercooled during processing. According to sensory evaluation, there was little difference in the shelf life of different fillet groups. Shelf life was estimated at 16-18 days, which is quite a long time for cod fillets. However, the freshness period of the experimental group SC-SC seemed to be somewhat longer than the other groups. As with whole cod, there was little difference between the fillet groups in terms of microbial growth, chemical and physical properties. Limited differences between experimental groups can possibly be explained by stable and supercooled storage conditions. With this in mind, it is planned to carry out another similar experiment, which will simulate more typical environmental temperature processes in the transport of fresh fish products (0–4 ° C) than in this experiment (–1.4 to –1.2 ° C).
The main aim of the study was to study the effects of superchilled processing on storage life of both whole fish and fillets. The following experimental groups were evaluated by means of temperature monitoring, chemical and microbial measurements and sensory evaluation, which were stored at mean temperatures of –1.4 to –1.2 ° C:
1) NC: non ‐ superchilled whole cod
2) SC: superchilled whole cod
3) NC ‐ NC: non ‐ superchilled fillets from non ‐ superchilled whole cod
4) NC ‐ SC: superchilled fillets from non ‐ superchilled whole cod
5) SC ‐ NC: non ‐ superchilled fillets from superchilled whole cod
6) SC ‐ SC: superchilled fillets from superchilled whole cod
The results from the sensory evaluation indicate that superchilled processing of whole cod can extend shelf life by two days. Differences in values of pH, water content, water holding capacity and bacterial growth between the superchilled and non ‐ superchilled whole fish groups were minor. Differences in sensory scores between the fillet groups were small. Shelf life was estimated between 16 and 18 days which is quite long shelf life for cod fillets. However, the SC ‐ SC group seemed to retain freshness a little longer than other groups. As in case of the whole cod, the differences in bacterial count, chemical and physical properties between the fillet groups were small. Very similar fish temperatures between both the whole fish and the fillets groups resulting from the superchilled storage conditions applied may be the main reason for the small differences obtained. Thus, another study with more common temperature conditions during transport and storage of fresh fish (chilled but not superchilled) will be performed.
