Doctoral dissertation in food science at the Faculty of Food and Nutrition at the School of Health Sciences, University of Iceland. Effects of different processes of action on the physical and chemical properties of fully processed salted fish.
On Wednesday 14 December. is defending his doctoral dissertation at the Faculty of Food and Nutrition, University of Iceland. Food scientist Minh Van Nguyen is defending his doctoral dissertation "The Effects of Different Processing Methods on the Physicochemical Properties of Heavily Salted Cod".
Opponents are dr. José Manuel Barat Baviera, Professor of Food Science, Universidad Politécnica de Valencia in Spain, and dr. Hörður G. Kristinsson, division and research director of Matís ohf. The instructor was Sigurjón Arason, Associate Professor at the Faculty of Food and Nutrition, University of Iceland and Chief Engineer at Matís ohf.
Dr. Inga Þórsdóttir, professor and 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 14:00.
Abstract from the study
Salted fish has been produced in Iceland and other countries since the 16th century. In recent years, the salting process of salted fish has developed a lot with the aim of improving the utilization and maintaining the quality of salted products during transport and storage. The process consists of different stages of salting and processing. It starts with pre-salting, spraying and / or pickling followed by dry salting. Appearance is a key factor when it comes to classifying products by quality. Jaundice that can be traced to muscle development can cause severe deterioration in quality. As a result, manufacturers' interest in the use of additives (such as polyphosphate) that can reduce development has increased. At present, however, phosphates have not been authorized as additives in salted fish processing. Scientific information on the activity and fate of phosphate in salted cod products is very limited.
The aim of this study was to gain a deeper knowledge of salted fish processing, with observations of mass flow and changes in the structure of proteins at different salt concentrations during pre-salting, as well as anti-corrosion properties and phosphate degradation in salted fish products. Furthermore, the effect of potassium ferrocyyanide (CN), a salt antifouling agent, on the oxidation (oxidation) of fats was investigated. In addition, the quality changes of salted cod were monitored at different storage temperatures.
The salinity of brine in pre-salting had a significant effect on the flow of salt and water into the muscle and thus on utilization and salting rate. Changes in protein imaging were dependent on the salinity of the muscle phase of the muscle Z- (NaCl), which could be explained by the salting-in of low-salt proteins (Z- (NaCl) <6%) and the de-salting-out of high-salt proteins ( Z- (NaCl)> 6%). The results showed that at Z- (NaCl) = 15%, the separation of dehydration and dehydration of proteins by brine was.
The results also showed that yellowing during salted fish processing is due to development and breakdown of fat. Development became faster with higher CN strength. However, the use of phosphate in the pre-salting process significantly decreased. To monitor the evolution (oxidation) of fat during the salting and storage of salted fish, measurements of fat derivatives (TBARS), spectra (b * values) and fluorescence were found. For) bestar. This study confirms that fluorescence measurements give a good picture of the amount of third-degree images during the development of salted fish products. It is not recommended to store products below -1 ° C. Storage at -4 ° C had a negative effect on quality, the color was darker and the amount of TVB-N higher than at the normal storage temperature (2 ° C).
Changes in the amount and composition of phosphate were determined by ion chromatography (IC) and spectrophotometric method. The added tri- and pyrophosphates decomposed in the salting process, i.e. pre-salting, dry salting, storage and dehydration. Most of the added and natural phosphates were flushed out of the muscle during dehydration. However, residues of added phosphates in dehydrated products could still be detected. There were differences in the results according to measurement methods, with IC the total amount of phosphate was lower than with light absorption measurement.
The doctoral dissertation is based on six scientific articles, of which four articles are already published in international scientific journals and two more have been submitted for publication.
In addition to the supervisor were on the doctoral committee Guðjón Þorkelsson, Associate Professor at the Faculty of Food and Nutrition, University of Iceland and Head of Department at Matís ohf., dr. Ágústa Guðmundsdóttir, professor at the Faculty of Food and Nutrition, University of Iceland, and dr. Kristín Anna Þórarinsdóttir, specialist manager at Matís ohf.
The United Nations University School of Fisheries awarded Minh Van Nguyen a scholarship and Matís ohf. provided his research facilities. The study belonged to projects funded by the AVS Fisheries Research Fund and the Technology Development Fund.
Starts: 14/12/2011 - 14:00
Location: Main building
Further location: Celebration hall
About the doctoral dissertation
Minh Van Nguyen was born in 1977 in Vietnam. He earned a bachelor's degree in food science in 2000 and an MS degree in 2004 from the Faculty of Aquatic Products Processing, Nha Trang University (NTU) in Vietnam. Since 2000, Minh Van Nguyen has been a lecturer in food science at Nha Trang University (NTU).
Minh Van Nguyen is married to Hoang Hai Yen and they have daughters Nguyen Thai Ha Anh and Nguyen Thai Ha Linh.
For further information Sigurjón Arason at Matís and the University of Iceland website, www.hi.is.