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Stavanger, Norway

Lovdal T.,University of Stavanger | Lovdal T.,Nofima Norconserv AS | Olsen K.M.,University of Stavanger | Slimestad R.,Saerheim Research Center | And 2 more authors.
Phytochemistry | Year: 2010

Tomato plants (Solanum lycopersicum, cv. Suzanne) were subjected to complete nutrient solution or a solution without nitrogen (N), and placed at different temperatures and light conditions to test the effects of environment on flavonoids and caffeoyl derivatives and related gene expression. N depletion during 4-8 days resulted in enhanced levels of flavonoids and caffeoyl derivatives. Anthocyanins showed pronounced increased levels when lowering the growth temperature from 24 °C to 18 °C or 12 °C. Flavonol levels increased when the light intensity was increased from 100 μmol m-2 s-1 PAR to 200 μmol m-2 s-1 PAR. Synergistic effects of the various environmental factors were observed. The increase in content of quercetin derivatives in response to low temperatures was only found under conditions of N depletion, and especially at the higher light intensity. Expression of structural genes in the phenylpropanoid and flavonoid pathways, PAL (phenylalanine ammonia lyase), CHS (chalcone synthase), F3H (flavanone 3-hydroxylase), and FLS (flavonol synthase) increased in response to N depletion, in agreement with a corresponding increase in flavonoid and caffeoyl content. Expression of these structural genes generally also increased in response to lower temperatures. As indicated through expression studies and correlation analysis, effects of N depletion were apparently mediated through the overall regulators of the pathway the MYB transcription factor ANT1 (ANTHOCYANIN 1) and SlJAF13 (a bHLH transcription factor orthologue of petunia JAF13 and maize RED genes). A PAL gene (PAL6) was identified, and correlation analysis was compatible with PAL6 being an actively expressed gene with function in flavonoid synthesis. © 2009 Elsevier Ltd. All rights reserved. Source

Foss A.,Akvaplan Niva | Grimsbo E.,University of Bergen | Vikingstad E.,Akvaplan Niva | Nortvedt R.,University of Bergen | And 2 more authors.
Fish Physiology and Biochemistry | Year: 2012

Investigation of the physiological effects of live chilling in Atlantic salmon, Salmo salar, has been performed in two experiments. In the first, fish (mean weight 840 g) acclimatized to either 16, 8, or 4°C were directly transferred horizontally or vertically (9 combinations) to water temperatures of 16, 8, 4, or 0°C using a dip net. Blood samples were collected at 1 and 6 h (h) post-transfer. In the second experiment, fish (mean weight 916 g) acclimatized to 16°C were exposed to four temperature-drop regimes (no physical handling): 16-4°C (over 5 h), 16-4°C (over 1 h), 16-0°C (over 5 h), and 16-0°C (over 1 h). Blood samples were collected 1 h post-temperature drop. Physical transfers in the first trial, i. e., temperature drops, resulted in immediate (1 h) increases in blood lactate concentrations at all three temperatures, but levels were significantly reduced and close to pre-transfer levels after 6 h. Horizontal transfers, i. e., 16-16°C, 8-8°C, and 4-4°C, resulted in similar increases and were not significantly different from the groups exposed to temperature drops. The most severe vertical transfer (16-0) resulted in a swift loss of equilibrium and eventually death. In experiment 2, temperature drops from 16 to 4°C and from 16 to 0°C over a period of one or 5 h, without physically handling the fish, resulted in no significant increases in any of the measured parameters 1 h post-transfer, except in the 16-0 (1 h) group. The latter experienced a significant increase in blood sodium, glucose, lactate, and cortisol levels compared to all other groups. The results suggest that salmon are capable of tolerating relatively steep temperature drops without any significant negative effects on blood stress parameters and that physical stress from handling overrides the effect of thermal insults. © 2011 Springer Science+Business Media B.V. Source

Rode T.M.,Nofima Materials AS | Rode T.M.,Nofima Norconserv AS | Axelsson L.,Nofima Materials AS | Heir E.,Nofima Materials AS | Holck A.,Nofima Materials AS
Applied and Environmental Microbiology | Year: 2011

Bacteriophages (phages) carrying Shiga toxin genes constitute a major virulence attribute in enterohemorrhagic Escherichia coli (EHEC). Several EHEC outbreaks have been linked to food. The survival of such strains in different foods has received much attention, while the fate of the mobile Shiga toxin-converting phages (Stx phages) has been less studied. We have investigated the stability of an Stx phage in several food products and examined how storage, food processing, and disinfection influence the infectivity of phage particles. The study involved a recombinant Stx phage (Δstx::cat) of an E. coli O103:H25 strain from a Norwegian outbreak in 2006. Temperature, matrix, and time were factors of major importance for the stability of phage particles. Phages stored at cooling temperatures (4°C) showed a dramatic reduction in stability compared to those stored at room temperature. The importance of the matrix was evident at higher temperatures (60°C). Phages in ground beef were below the detection level when heated to 60°C for more than 10 min, while phages in broth exposed to the same heating conditions showed a 5-log-higher stability. The phages tolerated desiccation poorly but were infective for a substantial period of time in solutions. Under moist conditions, they also had a high ability to tolerate exposure to several disinfectants. In a dry-fermented sausage model, phages were shown to infect E. coli in situ. The results show that Stx phage particles can maintain their infectivity in foods and under food-processing conditions. © 2011, American Society for Microbiology. Source

Altintzoglou T.,Nofima Marine | Einarsdottir G.,MATIS | Valsdottir T.,MATIS | Schelvis R.,IMARES | And 2 more authors.
Journal of Aquatic Food Product Technology | Year: 2010

This article describes a consumer-based approach for development of new seafood product concepts among young adults in Norway and Iceland. The study aim was to gain insight into how young adults determine their acceptance of seafood and make potential product choices. Additional insights measured were confidence in seafood preparation and consumption choices when exposed to specific new seafood concepts. Based on consumer-reported values, three seafood product concepts were evaluated by 354 consumers in a web-based, conjoint experiment in Norway and Iceland. Consumers' evaluations showed a number of consumer preferences for specific seafood product concepts partly associated with and partly conflicting with their original values. Understanding consumer attitudes can help to explain these results. The results of this study will be used as a guide for the next step in developing seafood product concepts. Copyright © Taylor & Francis Group, LLC. Source

Lerfall J.,Norwegian University of Life Sciences | Lerfall J.,Norwegian University of Science and Technology | Larsson T.,Norwegian University of Life Sciences | Larsson T.,Nofima Marin AS | And 7 more authors.
Aquaculture | Year: 2012

The impact of pancreas disease (PD) on fillet quality of raw and cold-smoked Atlantic salmon was investigated. Commercially reared fish were sorted into six groups: (1) Control (healthy fish), (2) SAV (infection with salmonid alphavirus, without PD outbreak), (3) PD0 (PD diagnosis at slaughter), (4) PD6 and (5) PD12 (diagnosed 5-7 and 11-12 months before slaughter, respectively) and (6) PDchronic (repeated PD outbreaks). The condition factor (CF) and fillet protein content were significantly higher for the control group (1.13 and 22.1%, respectively). The CF was lowest for PDchronic (0.92), whereas the fillet protein content was lowest in PD0 (20.2%). Fillet fat content did not vary significantly between the groups, but the muscle pH was 0.2 units higher in PD12 as compared to Control. Astaxanthin (Ax) and idoxanthin (Ix) content were significantly lowest for PD0. Ax recovered six months after the outbreak, but the Ix content remained lower in the PD affected salmon. The Ax level after smoking was similar for all groups, but Ix showed a similar pattern to that of raw fillets. Results of the colorimetric analyses (L*, a*, b*) indicated darkest colour for the control group and palest colour for PD0, whereas PDchronic showed highest differences between raw and smoked fillets. Firmness of raw fillets was lowest in PDchronic, but after smoking a significantly higher firmness was found in PDchronic, PD0 and PD6 (16.7-19.7 N) compared with that of Control and PD12 (14.1 N). Changes in fillet quality in the order of their appearance were decreased CF, depleted muscle glycogen, increased drip loss of raw muscle, paler colour, depleted protein and finally harder texture in smoked salmon. It is concluded that the fillet quality deteriorated after a PD outbreak, but the quality may to a large extent recover. © 2011 Elsevier B.V. Source

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