Finland-based VTT, the leading technical research institute in the Nordic countries, has come up with a new bio-based mineral oil barrier for use in food packaging. The invention tackles an issue that first became manifest in 2011: the migration of mineral oils into foods packaged in paper and board.
The main source of these mineral oils are thought to be the materials used for packaging, especially recycled paper and board, as these can contain ink from the newspapers that were recycled to make the cardboard boxes.
The mineral oils in question are divided into two groups: mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). Recycled cardboard contains different types of mineral oils, including those found in solvents, waxes and adhesives, which usually migrate by evaporating into gases that slowly enter foodstuffs over time. Once in the human body, these compounds are stored in various organs – liver, lymph nodes – and their exact impact remains unknown.
It’s a problem that is not going away. Last year, at the end of October, the Dutch branch of an international organization called Foodwatch published the results of a study it had carried out on 120 packaged dry foods in the Netherlands, Germany and France. 10 of the 120 tested products, or 83%, contained mineral oil saturated hydrocarbons (MOSH) and 43% contained mineral oil aromatic hydrocarbons (MOAH). The report stated that the situation in the Netherlands was far worse than in the other two countries, and that especially Germany has made the most progress in reducing the levels of contamination in products by switching packaging or using more effective mineral oil barriers.
VTT has now addressed this migration problem by developing wholly bio-based mineral oil barrier bags. The 2-layer film can be used as a ‘bag-in-box’ liner for dry foods such as breakfast cereals. These liners have, up until now, mostly been manufactured from conventional HDPE film – and evidently are inadequate to prevent the migration of mineral oil components into the packaged food products. Polyethylene inner bags typically first adsorb hydrocarbons and later release them towards the food.
VTT’s SutCo pilot foam coating line and new patent pending technology (PCT/FI2016/5075) based on the use of nanosized cellulose fibrils has been shown to decrease mineral oil migration to acceptable levels. Bio-based barrier bags prepared from Tempo-CNF coated bio-HDPE film protected the content to a great extent from mineral oil migration. There was no evidence of any leakages through heat-sealed areas of bags and completely transparent films behaved faultlessly during processing. Very low migration of each mineral oil component was obtained with Tempo-CNF coatings.
Migration after 7 days at 23°C for n-decane, isobutylbenzene, 1-cyclohexylbutane, 1-cyclohexylheptane and 1-cyclohexyldecane was 207, 173, 125, 13 and 1 mg/kg respectively. Significant reduction (>>90%) was attained as compared to non-coated bio-HDPE and other commercial cereal bag films.