Reports

Increased quality and stability of frozen herring products

Published:

01/11/2018

Authors:

Magnea Karlsdóttir, Huong Thi Thu Dang, María Guðjónsdóttir, Sigurjón Arason, Ásbjörn Jónsson

Supported by:

AVS R&D Fund (R 069-14)

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Increased quality and stability of frozen herring products

Freezing and cold storage is an effective method of maintaining quality and extending the shelf life of seafood. The production of frozen products equals the supply of products where fishing is seasonal. There are many factors that can affect the quality and stability of frozen products. These include the condition of the raw material, processing methods and conditions for storage and transport, to name but a few. The aim of the study was to investigate the changes that take place in the chemical and physical properties of frozen herring fillets with regard to the condition of raw materials during processing and conditions in cold storage. Atlantic herring was processed before and after death solidification, and the fillets were stored under stable storage conditions (-25 ° C) and unstable conditions (at -25 ° C for 2 months, then -12 ° C for one month and then again at - 25 ° C for the duration of storage). To study the stability and physical properties of the products, water loss (drip), boiling efficiency and color were measured, in addition to which both light and dark fish muscles were measured for water resistance, pH, chemical composition, fatty acid composition, enzyme activity and evolution. The study showed that it is important for the fishing industry to ensure uniform and correct temperature control when products are stored in the freezer. Processing and freezing before death solidification, in parallel with stable storage conditions, has a positive effect on the quality and stability of herring falcons. In addition, the study confirmed that the fatty state of the herring muscle, often referred to as the dark muscle, is very sensitive to development. In order to extend the shelf life of frozen herring fillets, it is recommended that this muscle be removed in parallel with deep skinning.

Freezing and frozen storage has proven to be an effective method to preserve and prolong the storage life of seafood products. Production of frozen products provides all year around product availability although the catching is seasonal. There are several factors that can affect the quality and stability of frozen fish products, including the state of the raw material, processing methods and storage conditions. The aim of the study was to explore how physicochemical properties of frozen herring fillets are affected with respect to the state of the raw material during processing as well as storage conditions. Atlantic herring was processed and frozen pre- and post-rigor and stored at stable (-25 ° C) and abused storage conditions. To investigate the storage stability and physical properties of the fillets, thawing drip, cooking yield and color were evaluated, as well as proximate composition, fatty acid composition, pH and lipid degradation of the light and the dark muscle. The study demonstrated the importance of stable and controlled temperature during storage and transportation of frozen herring products. Processing and freezing pre-rigor, in combination with stable storage conditions, was shown to be beneficial in terms of preventing lipid oxidation, as well as reducing thawing loss and maintaining the cooking yield of the herring fillets.

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