Grilstad wanted to modernise the packaging of its cured sausages. A challenge was to avoid oxygen getting into the package and meat becoming discoloured, so they involved Nofima in the quality control of the pack.
Hanne Larsen, a research scientist at Nofima, has been working on gas transmission rate and residual oxygen in the packages and minimising the problem of oxygen access to meat packaging.
She has developed a method for testing effects of different O2 concentrations and gas volumes on the discolouration when products are exposed to light.
Discoloration is a problem in Scandinavian countries, where processors use transparent packages for sliced meat products to appeal to consumers.
Changing from vacuum to modified atmosphere packaging (MAP) has introduced headspace volume and residual oxygen influencing the colour of cooked meat products.
Packaging: Consumer view
Grilstad did a consumer survey, which showed that the packaging was one of the weakest points.
Packs were difficult to open, they tore when opened, opening and closing functions did not work and they did not stay sealed.
Grilstad found the solution in a German butter pot with a screw top but it was not suitable for cured meats as the gas barrier needed improvement.
Larsen’s role was to evaluate the performance of the new packaging compared to the old under realistic storage conditions.
She performed tests with varying oxygen levels in the packs to minimise the risk of product discolouring under supermarket lighting.
Oxygen exposure impact
Larsen said with her work on sliced meat products, colour changes were a problem when the product was exposed to too much oxygen and light together.
“If there is too much oxygen with light the pink colour turns to grey and it doesn’t really look so good for the consumer," she told FoodQualityNews.com.
“Sliced ham is very sensitive, and a level of oxygen above 0.25% is all it takes to develop a grey colour. If you have 0.5% in the package and two days of light, you will get a grey look of the ham. The critical oxygen level for discolouration will also depend on the headspace volume in the package.
“Barrier layers and good seals with no leakages are needed to avoid oxygen entering the packages for sliced meat products. The tricky bit is the peel for consumer friendliness as you want easy opening without compromising the tight seal of the package.”