Salmon vs bacteria: lysozymes as food preservative

The bacteria-killing enzyme from salmon can have a new career as a food preservative, Nofima scientists have discovered.

All animals and humans have an enzyme group called lysozymes, which has the ability to "eat" and kill bacteria.

Scientists at Nofima (formerly Fiskeriforskning) in collaboration with Norstruct have carried out research to find the properties of one of salmon's two types of lysozymes - and these properties are unique.

Preserving

The fact is this natural component in salmon can be utilised on land to, for example, ensure that fresh food does not become full of bacteria.

"The salmon's lysozymes eat the cell wall of bacteria at temperatures of between zero and 40 degrees," says Senior Scientist Inge W. Nilsen. "This temperature window covers everything from refrigeration temperature to heat in the sun on a fine summer's day."

"The unique feature of this lysozyme is that the high temperature does not damage its ability to kill bacteria. When the temperature drops under 40 °C again, the enzyme resumes eating the bacteria."

No counterattack

But bacteria don't give up without a fight. They have a weapon to fight lysozymes, namely proteins which usually repress the enzymes.

"What distinguishes the salmon's lysozyme from such enzymes in humans and other land animals is that the usual bacteria weapons, proteins, don't attack this lysozyme," says Nilsen.

"Such properties are well suited as, for example, a preserving agent. I can imagine it being sprayed on fresh fish fillet or other fresh foods prior to packing."

The way forward

Nilsen believes commercial use of the salmon's lysozyme is likely.

"We in Nofima are assessing this for possible commercialisation" says Nilsen. The production code is "solved".

Utilisation of the salmon's lysozymes and its bacteria-killing properties for medical use is a further step up but a long way off.

The project is funded by the Research Council of Norway and Nofima.