Huong Thi Thu Dang, UNU-FTP fellow from Vietnam, will defend her PhD thesis entitled “Enhancing the quality of frozen fish products through improved processing and storage” on October 3 at the University of Iceland Main Building at 14:00.
Huong was a fellow of the United Nations University Fisheries Training Programme (UNU-FTP) in 2013/14, studying Quality Management of Fish Handling and Processing. Her final project there was on the effect of smoking methods on the quality of mackerel and her supervisors were Sigurjón Arason, Magnea Guðrún Karlsdóttir and Guðmundur Stefánsson.
In 2014 she received a PhD scholarship granted by the UNU-FTP and began her PhD studies in Food Science at the Faculty of Food Science and Nutrition University of Iceland from January 2015. Since 2000 she has been working as a lecturer and researcher at the Faculty of Food Technology Nha Trang University Vietnam.
Dr. Sigurjón Arason and dr. María Guðjónsdóttir, both professors at University of Iceland, were the lead advisors for her PhD training. On board the doctoral committee were also dr. Tumi Tómasson director of UNU-FTP, dr. Magnea G. Karlsdóttir from Matís and dr. Minh Van Nguyen associate professor at Nha Trang University Vietnam.
Huong PhD thesis centers on enhancing the quality of frozen fish products.
Freezing and subsequent frozen storage is an effective preservation method to maintain quality and extend shelf life of fish and fish products. Quality and storage stability of frozen fish products can be affected by the state of the raw material, processing methods, and conditions during storage and transport. The aim of this study was to gain a deeper understanding of the physicochemical changes in fish fillets during long-term frozen storage as affected by the initial raw material quality, processing and storage conditions, and how these changes affect product quality.
Golden redfish (Sebastes marinus) were caught in June and November 2015, processed and frozen on day 4 and day 9 post-catch and stored at -25 °C for up to 20 months. The effect of seasonal variation and material freshness on the quality and stability of the fish fillets during frozen storage was investigated. Atlantic herring (Clupea harengus) caught in November 2014 were used to compare the effect of pre-and post-rigor freezing and storage conditions (stress and stability at -25 °C for 5 months) on the quality and stability of frozen fish fillets. Effects of commercial processing additives (mixture of sodium phosphates, sodium chloride, and citric acid), packaging (vacuum and air packaging), and storage conditions (industrial frozen storage and controlled storage at -18.6±0.2 °C) for up to 12 months on the quality and stability of fish fillets during frozen storage were studied in Tra catfish (Pangasius hypophthalmus).
The study demonstrated that it is crucial to the fishing industry to ensure uniform and correct temperature control in their frozen storage facilities. Redfish caught in November outside the spawning season need to be handled with special care to maintain stability of quality during frozen storage. Treatment with additives combined with vacuum packaging are effective in protecting the quality of frozen pangasius.