Reports

Effects of bleeding methods on the quality and storage life of cod and saithe products

Published:

01/02/2014

Authors:

Magnea G. Karlsdóttir, Nguyen Van Minh, Sigurjón Arason, Aðalheiður Ólafsdóttir, Paulina E. Romotowska, Arnjótur B. Bergsson, Stefán Björnsson

Supported by:

AVS (R 11 087‐11)

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Effects of bleeding methods on the quality and storage life of cod and saithe products

The aim of the project was to examine the effect of different bleeding methods on the quality and shelf life of different cod and saithe products. By identifying ideal conditions for bleeding, gutting and bleeding, it is possible to prevent product defects due to blood and at the same time increase the stability of the products in transport and storage. The fish were either bloodied in the hands and in the machine. Bleeding took place in slush or sea and the effects of different bleeding times were examined. The effect of waiting time on tires before bleeding was also assessed, as well as bleeding and gutting the fish in one step or two steps (gutting performed after bleeding). The products studied in this project were chilled and frozen cod and saithe products, as well as salted cod products. Of the variables studied in this project, their importance differed in terms of which fish species were involved and what the final product was. When comparing comparable sample groups of cod and saithe, it is seen that different conditions are suitable for each species. This supports the theory that it is probably not possible to transfer the best bleeding method of cod to saithe and vice versa. Bleeding time and type of bleeding agent (sludge vs. seawater) had a decisive effect on the stability of the cod and saithe products examined. Cod products, both chilled and frozen, from raw material soaked in sludge generally resulted in improved quality and stability compared to if soaked in seawater. In contrast to cod, the bleeding of saithe into the sea generally resulted in a stable end product. The way the fish were bled and gutted also had a decisive effect on the final products. In the case of frozen cod products, raw and gutted raw material in one step generally yielded a more stable product compared to raw material that was gutted after bleeding had occurred (two steps). Salted products, on the other hand, were much more stable in storage if the raw material was gutted after bleeding. Different results were also obtained for saithe depending on the final product involved. Bleeding and gutting of saithe in a machine had a positive effect on the shelf life of chilled products compared to if made by hand. Machine bleeding and gutting, on the other hand, resulted in a much more unstable product in the cold. The results of the project show that the effects of different bleeding methods are quite dependent on the raw material as well as the final product involved.

The main objective of the project was to study the effects of different bleeding methods on quality and storage life of various cod and saithe products. Products defects due to blood residues can be prevented by optimizing bleeding protocols, and hence increase the quality and storage life of the products. For this, fishes were either bled and gutted by hand or by machine. The bleeding (blood draining) was carried out with seawater or slurry ice, and the effects of different bleeding times in the tanks were also investigated. Moreover, the effects of waiting time (on deck) before bleeding, as well as the procedure of bleeding technique (bleeding and gutting in one procedure vs. gutting after blood draining) were investigated. The various products evaluated were chilled and frozen cod and saithe products, and salted cod products. The importance of the different parameters investigated in this project varied considerably with regard to fish species and the final products. Comparison of parallel treatments groups of cod and saithe demonstrated that optimum bleeding procedures are different for each species. Waiting time on deck and bleeding media (slurry ice vs. seawater) significantly affected the storage life of the cod and saithe products. Cod products, both chilled and frozen, from fish bled in slurry ice generally resulted in improved quality and storage life compared to fish bled in seawater. In contrast to cod, bleeding or saithe in seawater resulted however in more stable products. The procedure during bleeding and gutting also had great impact on the storage life of the various products studied. Shorter storage life of salted cod products was generally observed when the raw material was bled and gutted in one step compared to when gutting was performed after bleeding (two steps). Rather conflicting results were, however, observed for saithe and were depending on the type of final product. Bleeding and gutting of saithe by machine improved the storage life of chilled products compared to when the saithe was bled and gutted by hand. The machine procedure had, however, negative effects on the storage life of the frozen saithe products. Overall, the results of this project indicate that the effects of different bleeding methods are highly relative to fish species as well as the final product of interest.

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Reports

Use of saithe in ready-made fish products / Using saithe in ready to eat fish product

Published:

01/03/2010

Authors:

Þóra Valsdóttir, Guðjón Þorkelsson, Irek Klonowski

Supported by:

AVS Fund / R 09075‐09

contact

Þóra Valsdóttir

Project Manager

thora.valsdottir@matis.is

Use of saithe in ready-made fish products / Using saithe in ready to eat fish product

Almost all saithe caught off Iceland is exported little processed, especially to Europe and the United States. There, it is largely processed into consumer products, which results in a considerable increase in value. It is important to explore ways to increase the value of exported saithe. By processing the saithe in full or for the most part in consumer products in Iceland, a higher proportion of the increase in value is passed on to domestic parties. In this summary, emphasis is placed on market conditions and the main production methods of breaded fish products, which have long been one of the most common further processing of Icelandic saithe abroad. Today there are market opportunities for products that are at a favorable price, of good quality, convenient and fast. Breaded saithe products fit well with these consumer demands. When a positive image of Icelandic food is added from an environmental point of view, it can be estimated that there are good opportunities for marketing Icelandic consumer products abroad. However, it is important to keep in mind to choose and know the market you are aiming for. Breaded fish is considered a relatively traditional food, but the variability within the product is considerable and much depends on the tastes of consumers in each country.

Most of the saithe caught in Icelandic waters is exported as raw material, mostly to Europe and the USA, where it is further processed to consumer products of higher value. In this summation emphasis is put on the market situation and processing methods of breaded fish products, which are probably the most common end ‐ product of Icelandic saithe abroad. Today is an opportunity for marketing of products which are economical, of high quality, convenient and quick to serve. Breaded fish products fulfill those requirements by ensuring raw material quality, processing and handling conditions. Great variety is within this product category which is now categorized as conventional food. Local preferences can vary greatly. Thorough selection and knowledge of markets is essential. There is a great potential for further processing of saithe into consumer products for export within Iceland due to proximity to the raw material and local knowledge of handling, ensuring the quality of the product. By further processing of the raw material higher proportion of the value of the final product will fall to the local producers, increasing the export value of saithe caught in Icelandic waters.     

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Reports

Use of saithe in ready-made fish products - final report / Using saithe in ready to eat fish product - final report

Published:

01/03/2010

Authors:

Þóra Valsdóttir, Irek Klonowski, Guðjón Þorkelsson

Supported by:

AVS-sjóðurinn / R 09075-09

contact

Þóra Valsdóttir

Project Manager

thora.valsdottir@matis.is

Use of saithe in ready-made fish products - final report / Using saithe in ready to eat fish product - final report

Almost all saithe caught off Iceland is exported little processed, especially to Europe and the United States. There, it is largely processed into consumer products, which results in a considerable increase in value. It is important to explore ways to increase the value of exported saithe. By processing the saithe in full or for the most part in consumer products in Iceland, a higher proportion of the increase in value is passed on to domestic parties. The project focused on methods for baking, which has long been one of the most common processing methods for Icelandic saithe abroad. The project got off to a good start and was soon contacted by potential buyers in Germany. Samples of products were sent to them for an assessment of how best to develop the product to their liking. Several experiments were carried out which indicated that the product development was on the right track. On the other hand, when the work progressed well, it was clear that Festarhald's operating basis was very uncertain and the company soon went into moratorium. Although the project developed in a different way than expected, the results of the experiments indicated that the products tested were of acceptable quality and likely to meet market requirements. There is therefore every reason to estimate that there is a basis for processing processed saithe products from saithe in this country. Today there are opportunities for products that are at a favorable price, of good quality, convenient and fast. Breaded saithe products fit well with these consumer demands. When a positive image of Icelandic food is added from an environmental point of view, it can be estimated that there are good opportunities for marketing Icelandic consumer products abroad.

Most of the saithe caught in Icelandic waters is exported as raw material, especially to Europe and the USA, where it is further processed to consumer products of higher value. In the project, analysis was performed on the potential of processing breaded fish products by a local processing plant. Results of experiments were positive and indicated that the products fulfilled market demands of composition and quality. There is a great potential for further processing of saithe into consumer products for export due to proximity to the raw material and local knowledge of handling, ensuring the quality of the product. By further processing of the raw material higher proportion of the value of the final product will fall to the local producers, increasing the export value of saithe caught in Icelandic waters.

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Reports

Chemical composition and properties of saithe isolate

Published:

01/07/2008

Authors:

Sigrún Mjöll Halldórsdóttir, Patricia Y. Hamaguchi, Ragnar Jóhannsson, Sigurður Hauksson, Hörður G. Kristinsson, Guðjón Þorkelsson

Chemical composition and properties of saithe isolate

Iceprotein ehf produces protein from raw fish wood with acid and alkali treatment. This process results in two layers: the upper layer is a protein isolate and the lower layer is a liquid phase. The liquid phase contains proteins that have not been used so far but have potential as food ingredients and as dietary supplements. Saithe proteins have a good chance of being a substance in health food if they are treated correctly. This could increase the value of saithe as it is a cheap and underutilized fish species. The purpose of this experiment was to investigate the possibility of utilization of the lower layer from acid and alkali treatment from saithe. The composition and properties of this substance were identified and its potential as a health food ingredient was concluded. Saithe was treated with acid and alkali and the lower layer was collected. The liquid phase was microfiltered and the protein mass was washed. Analysis of the chemical composition of the raw material, electrophoresis (SDS-PAGE), lyophilization, examination of the relationship between protein solubility and acidity and measurement of ACE inhibitory activity were performed. The results show that the material was about 95% water, 4% protein, 0.16% fat and 0.5% minerals. The proteins were insoluble in water, mostly myosin and actin and were not measured by ACE inhibitory activity. Future plans are to hydrolyze the proteins with enzyme technology to make them soluble and bioactive. Experiments will also be made with the addition of antioxidants to the material before and after enzyme treatment to prevent the oxidation of fats that otherwise degrade the taste quality.

Iceprotein ehf processes proteins from fish raw material with a pH-shift method. The pH-shift method results in two phases: the upper layer being the protein isolate and the lower layer a liquid phase containing insoluble proteins. These insoluble proteins have not been utilized so far but are potential food ingredients or nutritional supplements. If handled in the right manner, saithe proteins have good potential as ingredients in health foods. This way it would be possible to increase the commercial value of saithe which is an underutilized and inexpensive fish species. The purpose of this investigation was to explore the possibilities of utilizing the lower layer from saithe processed with the pH-shift method. The chemical composition and functional properties of the proteins in the lower layer were analyzed and their potential as health food ingredients explored. Saithe was processed with the pH-shift method and the lower layer was collected. The liquid phase was filtered and the protein mass was washed. The chemical composition was determined, the samples were subjected to electrophoresis (SDS-PAGE), freeze-dried, the relationship between solubility of the protein and pH was investigated, and the ACE-inhibiting function was measured. The results demonstrated that the material was 95% water, 4% protein, 0.16% fat and 0.5% minerals. The proteins were insoluble in water and consisted mostly of myosin and actin and did not show ACE-inhibiting activity. The future plan is to hydrolyze the material using enzyme technology to make them soluble and bioactive. Experiments in which antioxidants are added to the material will also be performed before and after enzyme treatment to prevent lipid oxidation which can have a negative effect on the product.

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