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Sigurjón Arason
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Impact of season, bleeding methods and storage temperature on the quality and stability of frozen cod climbs
The main goal of the project was to increase utilization and at the same time knowledge of the stability of cod climbing in frost according to the season. With increased knowledge of the effects of the season, the quality of raw materials and storage conditions on the stability of the liver in frost, it is possible to ensure that raw materials for further processing are available all year round. This report discusses the effects of the season, bleeding methods and storage temperature on the quality and stability of frozen cod climbs. Evaluation factors included enzymatic activity (free fatty acids) and evolution (primary and secondary subjects' evolution). Seasonality had a significant effect on the chemical composition and enzyme activity of the liver. This was reflected in higher fat content and higher levels of free fatty acids in the liver collected in July compared to liver from April. Frost stability also varied with the time of year as the liver from July was more susceptible to peroxide formation. Different bleeding methods (bleeding and gutting in one go (one step) and bleeding first and then gutting (two steps)) generally had little effect on the chemical composition and enzymatic activity of the liver. The haemorrhage methods, on the other hand, had a significant effect on the formation of a second-stage imagery of frostbite during storage, as the liver from fish bled in 2 steps was less craving compared to the liver from fish bled in one step. Storage temperature and time had a decisive effect on the stability of the livers in frost. Based on the available results, it is recommended to store frozen liver at -25 ° C rather than -18 ° C in order to slow down the damage process.
To our knowledge, there is limited information available regarding the effects of temperature, bleeding method, and seasonal variation on oxidation stability of cod liver during frozen storage. A profound knowledge of cod liver stability during frozen storage is needed to secure the available supply of cod liver for processing all year around. The objective of the present study was therefore to evaluate lipid deterioration during frozen storage of cod liver. The effects of temperature, storage time, bleeding method, and seasonal variation on lipid hydrolysis and oxidation were analyzed. Time of year significantly affected the chemical composition and enzymatic activity of the liver, which was reflected in a higher fat content and higher level of free fatty acids in the liver collected in July compared to liver collected in April. Stability during frozen storage also varied with season where liver from July was more vulnerable towards peroxidation. Different bleeding methods (bleeding and gutting in one step compared to bleeding first and then gutting (two steps)) had significant effect on the lipid oxidation where liver from fish bled in one step turned out to be more rancid compared to liver from fish bled in two steps. Storage temperature and time proved to be important factors with regard to lipid degradation of cod liver during frozen storage. Based on present results, in can be recommended to store frozen liver at - 25 ° C rather than -18 ° C in order to slow down these damage reactions.
