Reports

Chemical composition of silver - Seasonal fluctuations

Published:

26/08/2019

Authors:

Þóra Valsdóttir, Karl Gunnarsson

Supported by:

Fisheries Project Fund, AVS

contact

Þóra Valsdóttir

Project Manager

thora.valsdottir@matis.is

Chemical composition of silver - Seasonal fluctuations

The aim of the study was to examine the amount of nutrients, minerals and trace elements in oats by season to assess when it is best to harvest them from a nutritional point of view. Samples were taken at two locations, Tjaldanes by Saurbær in Dalasýsla and Herdísarvík by Selvogur in Reykjanes in the period from October 2011 to April 2013.

Seasonal fluctuations were detected in the content of nutrients in silver in both Herdísarvík and Tjaldanes and then followed the same process. In early spring, fiber, protein, fat, ash and water levels peaked. Measurements also indicated seasonal fluctuations in some of the minerals and trace elements measured; potassium, phosphorus, iodine, selenium, cadmium and lead. Heavy metals were within the limit limits with the exception of cadmium in winter.

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Reports

Impact of season, bleeding methods and storage temperature on the quality and stability of frozen cod climbs

Published:

01/04/2016

Authors:

Magnea G. Karlsdóttir, Sigurjón Arason, Ásbjörn Jónsson

Supported by:

AVS Fisheries Research Fund

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

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.

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Reports

Properties of silver. Impact of location and season / Properties of dulse. Influence of location and season

Published:

06/06/2011

Authors:

Þóra Valsdóttir, Karl Gunnarsson

Supported by:

AVS

contact

Þóra Valsdóttir

Project Manager

thora.valsdottir@matis.is

Properties of silver. Impact of location and season / Properties of dulse. Influence of location and season

This report reports on the results of a study of silver collected from June to October 2010 at two different growth sites of silver, on cliffs and boulders (Bolaklettar) and on islands (Fossárvík). The aim was to obtain reliable information on the effect of location and time of year on the appearance, nutritional value, amount of trace elements and minerals in silver in these places. The effect of season and location was measured on most of the measures analyzed, both composition and properties. The degree of variability varies depending on the factor involved. In some cases it can be significant and therefore important to collect silver in the places and time of year that is most favorable.

Dulse was collected from June to October 2010 at two different locations, rocky shore and at sandbank were the sea was mixed with fresh water. The aim was to collect data on the influence of location and season on the appearance and chemical composition of dulse. Significant differences were found on several attributes. Knowledge of the variability in ie color and protein content assist processors in selecting the most favorable raw material for their product.

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