Aquaculture and Fisheries News => Aquaculture News => ข้อความที่เริ่มโดย: pramaiporn ที่ สิงหาคม 10, 2010, 07:41:37 PM

หัวข้อ: Cod processing could be accelerated
เริ่มหัวข้อโดย: pramaiporn ที่ สิงหาคม 10, 2010, 07:41:37 PM
By using new methods, time, energy, transportation and packaging are reduced. (Photo: Bjorn Tore Rotabakk, Nofima)

Cod processing could be accelerated

Tuesday, August 10, 2010, 15:20 (GMT + 9)

Norwegian researchers claim that a novel bleeding method combined with superchilling has yielded “very promising results” for pre-rigor filleted farmed cod.

“In this test we have looked at the possibility of immediate gutting and filleting of unbled fish, followed by rinsing of the fillet. The aim is to considerably shorten the processing time for cod without being left with more blood in the fillet,” explained Bjørn Tore Rotabakk, a researcher at Nofima Mat (the Norwegian Institute of Food, Fisheries and Aquaculture Research) .

And because the entire process can be done in one place, time, energy, transportation and packaging are reduced, said Hogne Bleie, director of Biology and Biosafety at Atlantic Cod Farms AS.

Farmed cod intended for the European Union (EU) market now is often processed in Denmark, France or Poland. But no punitive duties on processed white fish in the EU exist, and the new method processing could occur near the fish farms, in Norway.

One set of farmed cod was bled in a usual bleeding vessel without movement. The fish were laid in seawater for 30 minutes to bleed out.
The second group of cod was instead gutted and filleted directly after being killed and then washed by sprinkling with fresh water for 10 minutes. This took place at Slakteriet Br Larsen AS in Bremanger.

Both groups were then divided into two. One was superchilled to about -1°C and packed in expanded polystyrene cases without ice, and the other was packed directly into expanded polystyrene cases and 3kg of ice was positioned atop.

All four groups were then transported and stored at 0°C for 6 days. The cases were sent by refrigerated transport and arrived after about two days.

After the cases were opened, drip loss was significantly cut by superchilling, while traditional bleeding gave substantially lower drip loss compared to the new bleeding method. Earlier tests at Nofima Mat gave the same results.

“The reason superchilling reduces drip loss in cod is not yet clear, but increased proteolysis and enzymatic and bacteriological activity because of higher temperatures may be a plausible explanation,” Rotabakk points out.

The greater drip loss with the new bleeding method versus traditional bleeding is because the fillets were weighed after 10 minutes of rinsing, which led to water being absorbed, which will be recorded as drip loss during storage when the water leaves the fillet.

No differences in colour were found between superchilled/ice and traditional bleeding and the new bleeding method, so it seems the new bleeding method works at least as well as the normal one.

“Texture analysis revealed that the new bleeding method gave a significantly (P=0.017) softer surface to the fillet than traditional bleeding. […] The superchilled cod was also significantly (P<0.001) softer in the surface of the fillet than cod iced in the normal way,” said Rotabakk.

The trials demonstrate that the new bleeding method works well.

More work must be carried out to optimise the washing process and it may be possible to lower the rinsing time.

By Natalia Real