Today, Friday 21 March, a doctoral defense will take place at the Faculty of Food and Nutrition, University of Iceland. Magnea Guðrún Karlsdóttir, a food scientist, defends her doctoral dissertation Oxidative mechanisms and stability of frozen fish products.
Opponents are dr. Santiago Aubourg Professor at CSIC in Spain (The Spanish Research Council) and dr. Sigríður Jónsdóttir researcher at the University of Iceland. Supervisors in the project were dr. Hörður G. Kristinsson and Professor Sigurjón Arason. Dr. Þórhallur Ingi Halldórsson, President of the Faculty of Food and Nutrition, will chair the ceremony, which will take place in the Celebration Hall of the University of Iceland in the Main Building and will begin at 14:30.
On the subject of the dissertation | Oxidation processes and stability of frozen seafood
Consumption of processed and frozen seafood has increased significantly in recent years due to growing consumer demand for convenient, high-quality food. Fats in fish products are a good source of polyunsaturated fatty acids (PUFA) which have been shown to have a positive effect on human health. Fish products with a high percentage of PUFA are extremely sensitive to evolution. Preservation of fat quality is therefore one of the main challenges when it comes to storage and processing of seafood. Freezing and cold storage is an effective method for preserving the quality and extending the shelf life of fish products, and it has been used for many years. Despite these advantages, the quality of the products can still deteriorate in cold storage. The aim of this project was therefore to increase knowledge of the different oxidation processes that take place in frozen fish products, as well as to study the variability between lean fish species in terms of stability during prolonged cold storage. The effect of different storage temperatures and raw material quality on the stability of fish products was studied, as well as the effect of heating and continued freezing of cooked products on the quality of the fat. Furthermore, the usefulness of various chemical and rapid measurements to monitor fat degradation was evaluated.
The research of this project provided a deeper understanding of the different processes of oxidation and stability of frozen seafood and how different storage conditions and variability of raw materials affect these processes. Temperature and storage time proved to be very important factors in the stability of frozen products. The quality and stability of the fat in the cold store was also highly dependent on fish species as well as muscle species. Furthermore, prolonged pre-cooking storage had the greatest effect on post-cooking fat stability.
A short summary in English
Consumption of processed and frozen fish has increased in recent years as a result of an increasing consumer demand for convenient high-quality food products. Fish lipids are a natural and good source of polyunsaturated fatty acids (PUFA) which have been reported to have several beneficial health effects. However, due to the high amount of PUFA fish lipids are highly susceptible to lipid degradation. Lipid quality preservation is therefore one of the major challenges associated with seafood raw material storage and subsequent processing for food use. Freezing and frozen storage is an effective method of preserving physicochemical properties and to prolong shelf life of fish products. However, some deterioration in fish quality occurs during frozen storage. Therefore, the aim of this project was to gain more understanding of different oxidative processes taking place in frozen fish products, and to investigate how two lean fish species with similar type of commercial utilization, differ in oxidative stability during prolonged frozen storage. The effects of different storage temperature and initial raw material quality on oxidative stability were studied, as well as the impact of cooking and subsequent cooked frozen storage on the lipid quality. Furthermore, the applicability of various chemical lipid quality markers and alternative non-invasive approaches to monitor fish lipid degradation was evaluated.
general information
Magnea Guðrún Karlsdóttir was born in 1978. She graduated with a bachelor's degree in food science in 2008 from the University of Iceland and an MS degree in food science in 2010. In addition to her studies, Magnea has worked for Matís and worked on various research projects.
Magnea's parents are Karl Jóhann Valdimarsson and Erla Þóra Óskarsdóttir. Magnea's husband is Ingvar Júlíus Tryggvason and they have four children together, Ástrós, Erla Ósk, Eva María and Tryggvi.