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Ottestad S.,Osloveien 1 | Ottestad S.,Norwegian University of Life Sciences | Enersen G.,Osloveien 1 | Wold J.P.,Osloveien 1
Journal of Food Science | Year: 2011

New freezing methods developed with the purpose of improved product quality after thawing can sometimes be difficult to get accepted in the market. The reason for this is the formation of ice crystals that can give the product a temporary color loss and make it less appealing. We have here used microscopy to study ice crystal size as a function of freezing temperature by investigating the voids in the cell tissue left by the ice crystals. We have also investigated how freezing temperature affects the color and the visible absorption spectra of frozen salmon. Freezing temperatures previously determined to be the best for quality after thawing (-40 to -60 °C) were found to cause a substantial loss in perceived color intensity during frozen state. This illustrated the conflict between optimal freezing temperatures with respect to quality after thawing against visual appearance during frozen state. Low freezing temperatures gave many small ice crystals, increased light scattering and an increased absorption level for all wavelengths in the visible region. Increased astaxanthin concentration on the other hand would give higher absorption at 490 nm. The results showed a clear potential of using visible interactance spectroscopy to differentiate between poor product coloration due to lack of pigmentation and temporary color loss due to light scattering by ice crystal. This type of measurements could be a useful tool in the development of new freezing methods and to monitor ice crystal growth during frozen storage. It could also potentially be used by the industry to prove good product quality. Practical Application: In this article we have shown that freezing food products at intermediate to low temperatures (-40 to -80 °C) can result in paler color during frozen state, which could affect consumer acceptance. We have also presented a spectroscopic method that can separate between poor product color and temporary color loss due to freezing. © 2011 Institute of Food Technologists ®.

Skugor A.,Osloveien 1 | Skugor A.,Norwegian University of Life Sciences | Tveiten H.,Muninbakken 9 13 | Krasnov A.,Osloveien 1 | And 2 more authors.
Animal Reproduction Science | Year: 2014

The RNA binding protein Dead end (DnD) is essential for maintaining viable germ cells in vertebrates and silencing of the gene has been demonstrated to cause sterility in several mammalian and fish species. Here we investigated transcriptome changes in hatched larvae of Atlantic cod induced by DnD knockdown using morpholino oligonucleotides (MO) injected in two-cell embryos. Whereas no fluorescently labeled germ cells were shown in embryos coinjected with dnd MO and nanos3 3'UTR coupled to green fluorescent protein, DnD knockdown had no visible effect on the number and location of Vasa protein positive cells in larvae. However, quantitative real-time RT-PCR (qPCR) revealed decreased vasa, nanos3 and tudor domain containing protein 7 mRNA expression and genome-wide oligonucleotide microarray analyses indicated profound suppression of genes involved in development and regulation of the reproductive system. DnD morphants showed lowered expression of genes encoding proteins involved in lipid, retinoid, cholesterol and steroid metabolism, including those with roles in sex hormone metabolism. Biotransformation of lipophilic compounds appeared suppressed too, as evidenced by down-regulation of several key genes from the phases 1 and 2 detoxification pathways. Effects of DnD silencing were highly pleiotropic and consisted of endocrine and metabolic changes, massive induction of histones and suppression of diverse developmental processes, including erythropoiesis and formation of extracellular matrix. While transient inhibition of dnd mRNA translation did not block development of primordial germ cells until hatch, results suggested that ablation of DnD might have major indirect consequences, including suppression of reproductive functions. © 2014 Elsevier B.V.

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