{"id":6015,"date":"2026-10-19T09:48:22","date_gmt":"2026-10-19T09:48:22","guid":{"rendered":"https:\/\/phd.hi.is\/doktorsvorn\/doktorsvorn-i-matvaelafraedi-huong-thi-thu-dang\/"},"modified":"2026-10-19T09:48:22","modified_gmt":"2026-10-19T09:48:22","slug":"doktorsvorn-i-matvaelafraedi-huong-thi-thu-dang","status":"publish","type":"phd_defence","link":"https:\/\/phd.hi.is\/en\/doktorsvorn\/doktorsvorn-i-matvaelafraedi-huong-thi-thu-dang\/","title":{"rendered":"Doktorsv\u00f6rn \u00ed matv\u00e6lafr\u00e6\u00f0i – Huong Thi Thu Dang"},"content":{"rendered":"
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Mi\u00f0vikudaginn 3. okt\u00f3ber n\u00e6stkomandi ver Huong Thi Thu Dang doktorsritger\u00f0 s\u00edna \u00ed matv\u00e6lafr\u00e6\u00f0i vi\u00f0 Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands. Ritger\u00f0in ber heiti\u00f0: Aukning g\u00e6\u00f0a frosinna fiskafur\u00f0a me\u00f0 \u00fev\u00ed a\u00f0 b\u00e6ta vinnslu og geymslu. Enhancing the quality of frozen fish products through improved processing and storage.<\/strong><\/p>\n

Andm\u00e6lendur eru dr. Ragnar Ludvig Olsen Norwegian College of Fishery Science, University of Troms\u00f8, Norway og dr. Santiago Aubourg pr\u00f3fessor hj\u00e1 CSIC \u00e1 Sp\u00e1ni.<\/p>\n

Umsj\u00f3narkennarar og lei\u00f0beinendur voru dr. Sigurj\u00f3n Arason pr\u00f3fessor vi\u00f0 Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands og yfirverkfr\u00e6\u00f0ingur hj\u00e1 Mat\u00eds og dr. Mar\u00eda Gu\u00f0j\u00f3nsd\u00f3ttir pr\u00f3fessor vi\u00f0 Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands. Auk \u00feeirra s\u00e1tu \u00ed doktorsnefnd dr. Tumi T\u00f3masson forst\u00f6\u00f0uma\u00f0ur H\u00e1sk\u00f3la Sameinu\u00f0u \u00fej\u00f3\u00f0anna, dr. Magnea G. Karlsd\u00f3ttir, Mat\u00eds og dr. Minh Van Nguyen\u00a0 d\u00f3sent vi\u00f0 Nha Trang University, V\u00edetnam.<\/p>\n

Dr. Brynd\u00eds Eva Birgisd\u00f3ttir, pr\u00f3fessor vi\u00f0 Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands, stj\u00f3rnar ath\u00f6fninni sem fram fer \u00ed H\u00e1t\u00ed\u00f0asal H\u00e1sk\u00f3la \u00cdslands og hefst kl. 14:00.<\/p>\n

\u00c1grip af ranns\u00f3kn<\/strong><\/p>\n

Frysting og frostgeymsla er skilvirk a\u00f0fer\u00f0 til a\u00f0 vi\u00f0halda g\u00e6\u00f0um og lengja geymslu\u00feol sj\u00e1varafur\u00f0a. Framlei\u00f0sla \u00e1 frosnum afur\u00f0um jafnar frambo\u00f0 sj\u00e1varafur\u00f0a \u00feegar vei\u00f0ar og sl\u00e1trun eldisfisks eru \u00e1rst\u00ed\u00f0abundnar. \u00c1stand hr\u00e1efnis, vinnslua\u00f0fer\u00f0ir og skilyr\u00f0i vi\u00f0 geymslu og flutning getur haft \u00e1hrif \u00e1 g\u00e6\u00f0i og st\u00f6\u00f0ugleika frosinna afur\u00f0a. Markmi\u00f0 ranns\u00f3knarinnar var \u00fev\u00ed a\u00f0 \u00f6\u00f0last d\u00fdpri skilning \u00e1 e\u00f0lisfr\u00e6\u00f0ilegum breytingum \u00e1 fl\u00f6kum \u00feriggja fisktegunda me\u00f0an \u00e1 langt\u00edma geymslu \u00ed frosti stendur, og kanna hva\u00f0a atri\u00f0i hafa \u00e1hrif \u00e1 g\u00e6\u00f0i \u00feeirra.<\/p>\n

Gullkarfi (Sebastes marinus) var veiddur su\u00f0vestur af \u00cdslandi \u00ed j\u00fan\u00ed og n\u00f3vember 2015, flaka\u00f0ur og frystur \u00e1 4. og 9. degi eftir vei\u00f0i, og geymdur vi\u00f0 -25 \u00b0C \u00ed allt a\u00f0 20 m\u00e1nu\u00f0i. Ranns\u00f6ku\u00f0 voru \u00e1hrif \u00e1rst\u00ed\u00f0abundinna breytinga og \u00e1hrif ferskleika vi\u00f0 vinnslu \u00e1 st\u00f6\u00f0ugleika frosinna karfaflaka. Atlantshafss\u00edld (Clupea harengus) var veidd vestur af \u00cdslandi \u00ed n\u00f3vember 2014 og unnin annars vegar fyrir dau\u00f0astir\u00f0nun og hins vegar eftir dau\u00f0astir\u00f0nun. Ranns\u00f6ku\u00f0 voru \u00e1hrif \u00feessara breyta \u00e1 st\u00f6\u00f0ugleika s\u00edldarafur\u00f0a \u00ed frystigeymslu vi\u00f0 -25 \u00b0C \u00ed 5 m\u00e1nu\u00f0i. Pangasus (Pangasius hypophthalmus) \u00far fiskeldi var flaka\u00f0ur \u00ed V\u00edetnam og ranns\u00f6ku\u00f0 \u00e1hrif aukefna (blanda af natr\u00edumfosfati, natr\u00edumkl\u00f3r\u00ed\u00f0i og s\u00edtr\u00f3nus\u00fdru) og umb\u00fa\u00f0a \u00e1 st\u00f6\u00f0ugleika afur\u00f0a voru rannss\u00f6ku\u00f0 vi\u00f0 -18,6 \u00b1 0,2 \u00b0C \u00ed allt a\u00f0 12 m\u00e1nu\u00f0i.<\/p>\n

Ranns\u00f3knin s\u00fdndi a\u00f0 \u00fea\u00f0 er mikilv\u00e6gt fyrir sj\u00e1var\u00fatveginn a\u00f0 tryggja samr\u00e6mda og r\u00e9tta hitast\u00fdringu \u00feegar afur\u00f0ir eru geymdar \u00ed frosti. Karfa, sem veiddur er \u00ed n\u00f3vember, utan hrygningart\u00edmabilsins, \u00fearf a\u00f0 me\u00f0h\u00f6ndla me\u00f0 vark\u00e1rni til a\u00f0 tryggja r\u00e9tt g\u00e6\u00f0i frosinna afur\u00f0a. Fr\u00e1gangur og vinnsla fisks skal gerast eins flj\u00f3tt og au\u00f0i\u00f0 er eftir vei\u00f0i. Hins vegar, ef r\u00e9tt er sta\u00f0i\u00f0 a\u00f0 me\u00f0h\u00f6ndlun fisks, \u00fe\u00e1 m\u00e1 lengja vei\u00f0ifer\u00f0 og t\u00edma \u00e1\u00f0ur en vinnsla hefst. Notkun aukefna vi\u00f0 vinnslu frosinna pangas\u00edusflaka og p\u00f6kkun \u00ed loftt\u00e6mdar umb\u00fa\u00f0ir tryggir g\u00e6\u00f0i \u00feeirra. Me\u00f0 \u00fev\u00ed a\u00f0 nota ro\u00f0flettiv\u00e9l sem fjarl\u00e6gir d\u00f6kka v\u00f6\u00f0vann (ro\u00f0skur\u00f0ur) er einnig h\u00e6gt a\u00f0 lengja geymslu\u00feol frosinna fiskflaka umtalsvert.\u00a0 Hins vegar m\u00e1 vinna ol\u00edu \u00far d\u00f6kkv\u00f6\u00f0vanum til til a\u00f0 tryggja skilvirka n\u00fdtingu hr\u00e1efnisins.<\/p>\n

Lykilor\u00f0:<\/strong> Gullkarfi, s\u00edld, pangas\u00edus, \u00e1rst\u00ed\u00f0asveiflur, ferskt hr\u00e1efni, dau\u00f0astir\u00f0nun, aukefni, p\u00f6kkun, frystigeymsla, hitasveiflur, e\u00f0lis- og efnafr\u00e6\u00f0ilegir eiginleikar.<\/p>\n

Abstract <\/strong><\/p>\n

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.<\/p>\n

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 \u00b0C 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 \u00b0C 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\u00b10.2 \u00b0C) for up to 12 months on the quality and stability of fish fillets during frozen storage were studied in Tra catfish (Pangasius hypophthalmus).<\/p>\n

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.<\/p>\n

Keywords:<\/strong> Golden redfish, Atlantic herring, Tra catfish\/pangasius, season of capture, raw material freshness, pre-rigor, post rigor, additives, packaging, frozen storage, temperature stress, physicochemical properties.<\/p>\n

Um doktorsefni\u00f0<\/strong><\/p>\n

Huong Thi Thu Dang was born in 1977.\u00a0 She completed her BSc degrees and MSc in Aquatic Processing Technology in 2000 and 2004, respectively from Nha Trang University (formerly the University of Fisheries), Vietnam. In 2013, she attended the six months training course in Quality Management of Fish Handling and Processing that was hosted by the United Nations University – Fisheries Training Programme (UNU-FTP), Iceland. 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, Iceland from January 2015. Since 2000, she has been working as a lecturer and researcher at the Faculty of Food Technology, Nha Trang University, Viet Nam. Huong is now living in Nha Trang, Vietnam with her husband Luong Duc Nam and their daughter Luong Dang Ngoc Minh and their son Luong Duc Binh.<\/p>\n<\/div><\/div>","protected":false},"featured_media":1260,"template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_phd_date_start":"2018-10-03T14:00:00+00:00","_phd_date_end":"2018-10-03T17:00:00+00:00","_phd_location":"A\u00f0albygging H\u00e1t\u00ed\u00f0arsalur","_phd_admission":"A\u00f0gangur \u00f3keypis","_phd_thesis_title":"Aukning g\u00e6\u00f0a frosinna fiskafur\u00f0a me\u00f0 \u00fev\u00ed a\u00f0 b\u00e6ta vinnslu og geymslu. 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