María Gudjónsdóttir
Technical University of Denmark
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Publication
Featured researches published by María Gudjónsdóttir.
Journal of Food Science | 2009
Hélène L. Lauzon; Hannes Magnússon; Kolbrún Sveinsdóttir; María Gudjónsdóttir; Emilía Martinsdóttir
The aim of these experiments was to evaluate the effect of brining, modified atmosphere packaging (MAP), and superchilling on the quality changes of cod loins as measured by microbial, sensory, and chemical analysis. Unbrined and brined (2.5 +/- 1.0% NaCl) cod loins were kept in styrofoam boxes (air) and under modified atmosphere (MA, CO(2)/O(2)/N(2): 50/5/45) at 0, -2, and -3.6 degrees C. Samples were examined over a 4-wk period. Total viable psychrotrophic counts and counts of H(2)S-producing bacteria reached higher numbers in the air-packed brined fish at -2 and -3.6 degrees C than in comparable unbrined groups, being significantly different (P < 0.05) at the lower temperature. However, lower counts of these bacteria were obtained in the brined MAP fish than in comparable unbrined fish. Counts of Photobacterium phosphoreum increased most rapidly in air- and MA-packed loins kept at 0 degrees C. Lower counts were found at superchilled temperatures. According to sensory analysis the shelf life of unbrined air-packed loins was about 11 d at 0 degrees C and 14 to 15 d at -2 degrees C. The shelf life of MA-packed unbrined loins was about 14 to 15 d at 0 degrees C but 21 d at -2 degrees C. Thus, synergism of combined superchilling (-2 degrees C) and MA led to a considerable shelf life increase for unbrined loins despite the fact that processing and packaging took place 4 to 5 d post-catch. The shelf life of air-packed brined loins at -2 degrees C was 12 to 15 d but only 13 d under MA. The same synergistic effect did therefore not apply to brined loins as with unbrined ones.
Journal of Food Science | 2011
María Gudjónsdóttir; Ásbjörn Jónsson; Arnljótur Bjarki Bergsson; Sigurjón Arason; Turid Rustad
The effect of using polyphosphates during prebrining and the effect of prebrining time of cold water shrimp (Pandalus borealis) was studied with low field nuclear magnetic resonance (LF-NMR) transverse relaxation time measurements (benchtop and unilateral) and near infrared (NIR) spectroscopy with the aim of improving shrimp processing. Strong calibrations were obtained for moisture content and water-holding capacity (WHC) using the NIR technique. Multivariate analysis indicated significant correlations between benchtop NMR parameters and moisture content and WHC, as measured with physicochemical methods and NIR spectroscopy. Significant correlations were also observed between NMR parameters and muscle pH, protein content, and phosphate content. The study showed that LF-NMR contribute to improved understanding of the shrimp brining process and to improved process control on-line or at-line, especially in combination with NIR measurements. However, optimization of the unilateral device is necessary.
Journal of Food Science | 2010
María Gudjónsdóttir; Valur N. Gunnlaugsson; Gudrun A. Finnbogadottir; Kolbrun Sveinsdottir; Hannes Magnússon; Sigurjon Arason; Turid Rustad
The aim of this study was to use low-field nuclear magnetic resonance (NMR) and traditional chemical methods to investigate the physical and chemical differences in wild and farmed cod processed pre- and postrigor, and how these properties were affected by brine injection, brining, and freezing. In prerigor processed farmed or wild cod, brine injections followed by brining for 2 d, with brine concentrations up to 5.5% and 4%, respectively, were not sufficient to reach a muscle salt concentration of 2% as aimed for, while wild cod processed postrigor had sufficient salt uptake after the same processing. Low-field NMR gave valuable information about the differences in the muscle structure between wild and farmed cod as well as the state of the water in the muscle during brine injection, brining, and during rigor tension. Low-field NMR is, therefore, a valuable tool that can be used to optimize the salting and storing processes of lightly salted cod products from both wild and farmed cod. For farmed cod to be used in the production of lightly salted products further research is needed. Practical Application: Optimal processing of lightly salted cod products is important to the fish industry, due to an increasing market for this product in southern Europe. Farmed cod, which is seen as a potential steady raw material source for this production, differs considerably from its wild counterparts by having other chemical and physical muscle properties, such as lower water content and lower pH. With the processing procedures used today the farmed cod can, therefore, only be used in some of the products, where wild cod is currently used as raw material. It is, therefore, important that the processing of these products is optimized with regard to these differences in the raw material. This study gives a valuable contribution to further studies about optimal combinations of brine injections, brining, and freezing of pre- and postrigor processed farmed compared to wild cod.
Food Chemistry | 2015
María Gudjónsdóttir; Manuel D. Gacutan; Ana Carina Loureiro Mendes; Ioannis S. Chronakis; Lene Jespersen; Anders Karlsson
The effects of using electrospun chitosan fibres as a wrapping material for dry-ageing beef was studied and compared to traditional dry-ageing and wet-ageing of beef for up to 21 days. The chitosan treatment showed improved results in terms of yield, reduction of microbial counts, yeasts and moulds, and lighter appearance compared to traditional dry-ageing. Weight and trimming losses were minimal in the wet-ageing beef. However, significant growth of lactic acid bacteria was observed in this group. Transverse relaxation times indicated a lower degree of muscle denaturation during ageing in the chitosan dry-ageing beef compared to the traditional dry-ageing meat. A principal component analysis furthermore indicated that 60.6% of the variation between samples and ageing treatments could be described by differences in the water content and distribution in the muscle. The study showed that electrospun chitosan fibre mats have potential as a wrapping material for improved quality during dry-ageing of beef.
Food Chemistry | 2015
María Gudjónsdóttir; Amidou Traore; Ásbjörn Jónsson; Magnea G. Karlsdóttir; Sigurjon Arason
The effect of different pre-salting methods (brine injection with salt with/without polyphosphates, brining and pickling) on the water and salt distribution in dry salted Atlantic cod (Gadus morhua) fillets was studied with proton and sodium NMR and MRI methods, supported by physicochemical analysis of salt and water content as well as water holding capacity. The study indicated that double head brine injection with salt and phosphates lead to the least heterogeneous water distribution, while pickle salting had the least heterogeneous salt distribution. Fillets from all treatments contained spots with unsaturated brine, increasing the risk of microbial denaturation of the fillets during storage. Since a homogeneous water and salt distribution was not achieved with the studied pre-salting methods, further optimizations of the salting process, including the pre-salting and dry salting steps, must be made in the future.
Journal of Food Science and Technology-mysore | 2013
María Gudjónsdóttir; Magnea G. Karlsdóttir; Sigurjon Arason; Turid Rustad
Low field Nuclear Magnetic Resonance was used in comparison to yield and physicochemical measurements to assess the effects of salt and protein injection on the properties of saithe (Pollachius virens) fillets during chilled and frozen storage. Saithe fillets injected with various combinations of salt, homogenized fish proteins, gelatine and fish protein hydrolyzate, were compared to the properties of untreated fillets. Addition of salt or fish protein hydrolyzate resulted in increased yield after cooking and water holding capacity compared to other treatments. Transversal relaxation data fitting resulted in three water populations with relaxation times of 27–45xa0ms, 60–99xa0ms and 187–341xa0ms. Relaxation times and respective populations showed significant correlation to various physicochemical properties, that muscle water behaviour was changed by salt and protein injection and indicated protein denaturation during frozen storage. Fish protein hydrolyzate injected fillets were most stable through storage, while gelatine injected fillets were most denatured during frozen storage.
Journal of Food Engineering | 2011
María Gudjónsdóttir; Sigurjon Arason; Turid Rustad
Food Research International | 2011
María Gudjónsdóttir; Hélène L. Lauzon; Hannes Magnússon; Kolbrún Sveinsdóttir; Sigurjon Arason; Emilía Martinsdóttir; Turid Rustad
Food Control | 2011
Nga Thi Tuyet Mai; María Gudjónsdóttir; Hélène L. Lauzon; Kolbrún Sveinsdóttir; Emilía Martinsdóttir; Hubert Audorff; Werner Reichstein; Dietrich Haarer; Sigurdur G. Bogason; Sigurjon Arason
Food Hydrocolloids | 2015
Hilal Yilmaz Celebioglu; María Gudjónsdóttir; Sebastian Meier; Jens Ø. Duus; Seunghwan Lee; Ioannis S. Chronakis