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Stavanger, Norway

Merkin G.V.,University of Bergen | Roth B.,Nofima Norconserv | Gjerstad C.,University of Bergen | Nortvedt R.,University of Bergen

The aim of this study was to investigate the effects of pre-slaughter procedures on stress responses and flesh quality in sea-farmed rainbow trout (Oncorhynchus mykiss). A total of 114 fish were slaughtered 1) at the farm, 2) after transport, 3) after 4days in the holding cage and then 30-50min crowding, 4) after pumping, 5) after pumping and electrical stunning, 6) after 4h crowding and 7) after 4h crowding and pumping. Blood samples were collected from the fish at consecutive pre-slaughter stages. The time course of rigor mortis was evaluated for 72h post mortem. Fillet cuts were evaluated for such quality parameters as gaping and weight loss after ice or frozen storage. The results show that, in most cases, blood cortisol, lactate and pCO2 levels increased while blood pH and pO2 decreased according to the number of events added to the slaughter process. A significant increase in hematocrit and blood glucose after transportation was observed. Both crowding and pumping led to acceleration in onset of rigor mortis, whereas transportation and electrical stunning did not show any significant effect on rigor development. The severity of gaping and the degree of weight loss were not significantly affected by fish pumping and electrical stunning. We conclude that pre-slaughter procedures such as crowding and pumping cause stress and affect flesh quality accelerating the onset of rigor mortis in sea-farmed rainbow trout. © 2010 Elsevier B.V. Source

Stormo S.K.,Nofima Marin | Sivertsen A.H.,Nofima Marin | Heia K.,Nofima Marin | Skipnes D.,Nofima Norconserv
Food Control

From a microbiological point of view thermal processing is useful to preserve food and keep it safe. Assessing endpoint temperatures (EPT) enables effective temperature control throughout processing, but assessment methods have so far been labour-intensive or sensitive to water associated with the sample. The aim of this study was to develop a non-invasive method able to deal with the water levels of fresh samples. Visible spectroscopy measurements were combined with multivariate analysis for EPT prediction of surimi samples. No measures were carried out to control the water on the surface or the water content of the samples. In the range from 400 to 700 nm an apparent correlation between temperature treatment and spectra intensities was observed. The spectral changes reflect the changes in relative scattering intensities caused by protein denaturation. A similar correlation was not observed for the near infrared (NIR) region. By excluding the NIR region, where water absorbs strongly, we present a model in range from 400 to 700 nm that show a prediction error less than 2 °C in the temperature range 46.6-74.4 °C. This model is robust (r 2 = 0.96) and covers the temperature range for mild surface pasteurization, thereby showing potential for use in the food processing industry. © 2011 Elsevier Ltd. Source

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