IIR document

Weight loss on whole salmon during freezing in tunnel with various product sizes and process parameters.

Number: pap. ID: 461



The objective of this study was to investigate weightloss of gutted whole salmon during freezing in traditional tunnel with various product and process parameters. Air temperature, core and surface temperature were continous registrated and weightloss of 6 salmons from each parameter were measured at 0, 1.5 and 22.5 hours. Weightloss during and after freezing in tunnel were measured with following changes of parameters: the size of the salmon, 4 and 8 kg; core temperature of 0 contra 6°C in the salmon before freezing; air temperatatur of -25 and -35°C in the tunnel during freezing; air velocity in the end of the freezing period. A large fish needs longer freezing time than a smaller fish. Weightloss of 4 versus 8 kg salmon were measured, and no significant variations in weightloss was registrated between the two sizes. There is an indication that larger fishes have a higher weightloss initially in the freezing periode. This is also registrated in other studies were thicker pork carcasses had a larger weightloss in the earliest stage. Freezing of salmon is normally done as last step after production of fresh chilled salmon were it is desirable to chill the fresh salmon as close to 0°C before it is put in boxes with ice and transported to the market. It is normal to reduce the initial chilling for the fish planed for freezing to release cooling capacity for the fresh production. The fish temperature will then be higher before it enters the freezing tunnel. Salmon with initial core temperature of 6°C was compared with 0°C regarding wightloss during freezing, and no significant variations in weight loss between the two different initial core temperatures was detected. Reducing the freezing temperatur will increase the heatflux from the product, and the freezing time will decrease. Weight loss of salmons was measured during freezing at air temperature at -25 and -35°C. There were significant variations in weightloss between the temperatures, and freezing at -35°C reduces the weightloss with 0.25% compared with -25°C. Industrial freezing of whole salmon in tunnels are normally batch processes. The fan is often running at high speed at all times although the heatflux reduces as the fish temperatur decreases but. The effect on weightloss by reducing the air speed at the end of the freezing periode was performed, and showed a significant increase when the fan was not stoped after the desired core temperature was reached. It is important to reduce the fan speed as soon as the heat transfere from the fish is reduced. In addition to redusing weightloss, there is also important regarding the energy use. Surveys show that in industrial freezing tunnels fans counts for nearly 30% of the total energy use.

Available documents

Format PDF

Pages: 7 p.


  • Public price

    20 €

  • Member price*


* Best rate depending on membership category (see the detailed benefits of individual and corporate memberships).


  • Original title: Weight loss on whole salmon during freezing in tunnel with various product sizes and process parameters.
  • Record ID : 30003075
  • Languages: English
  • Source: Proceedings of the 23rd IIR International Congress of Refrigeration: Prague, Czech Republic, August 21-26, 2011. Overarching theme: Refrigeration for Sustainable Development.
  • Publication date: 2011/08/21


See other articles from the proceedings (569)
See the conference proceedings