Title: Combined application of modified atmosphere packaging (MAP) and superchilled storage to extend the shelf-life of fresh cod (Gadus morhua) loins

Author(s): Wang Tao
Final project
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Supervisors: Kolbrun Sveinsdottir
modified atmosphere packaging; superchilled storage; fresh cod loins; shelf-life; sensory evaluation; microbial analysis.


To meet the increasing demand for value-added fresh cod loins in the EU retail market, it is important to develop new technologies and preservation methods to effectively extend the shelf-life and improve the eating quality of fresh cod loins. The aim of this study was to investigate the effects of combined application of MAP and superchilled storage on the shelf-life extension of fresh cod loins. The influence of MA packaging (50.0% CO2-45.0% N2 -5% O2) and storage temperature (1.5°C or -1°C) to prolong the shelf-life of cod loins was evaluated by sensory analysis (Quality Index Method (QIM) and Quantitative Descriptive Analysis (QDA)), physical, chemical and microbial analysis. Compared with traditional chilled storage in polystyrene boxes (1.5°C), MA packaging and superchilled storage alone increased the shelf-life of cod loins from nine to 14 and 16-17 days. When combined, a synergistic effect was observed and the shelf-life might be further extended to at least 24 days. It is noteworthy that the characteristic fresh and sweet taste can be maintained up to 18 days. This could contribute to improved eating quality of fresh cod loins for consumers in distant markets.The results of multi-indicator evaluation by PCA indicated that QIM seems more feasible to evaluate the marketability of the fresh cod loins than other quality indicators, although some modifications are needed. High correlation was found between QIM and TVC, H2S - producer, P. phosphoreum, indicating that these microbial variables gave similar information as QI scores. TVB-N, TMA and pH gave more information about the onset of putridity and did not reflect the earlier stages of spoilage. MAP combined with superchilled storage might have an impact on the textural properties. There is a significant difference of meaty texture among superchilled MA packed cod loins and other groups after seven days of storage. Accordingly, drip losses reached levels of 4.7-5.3% after 13 days of storage.

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