Internal bags with barrier layers for foods packed in recycled paperboard: recent progress

Abstract

Internal bags for packaging dry foods into boxes of recycled paperboard, collected in Dresden and Zurich in June 2013, were investigated with regard to the layer composition and the barrier efficiency against substances migrating from the recycled fibers. The layers were identified by microtome cuts and Fourier transform infrared spectroscopy, often after wet-chemical separation of the layers. The barrier efficiency was tested with five surrogate substances and classified between 1 and 5, with class 1 having no significant barrier effect, 4 being a virtually tight barrier consisting of polymeric material and 5 including an aluminum foil. Merely 17 of the 87 bags (20 %) consisted of paper or polyethylene that constituted insignificant barriers. Bags of oriented polypropylene, substantially reducing migration (class 2), were encountered in 32 % of the packs; those with more efficient, but still incomplete barriers (class 3) in 16 % and virtually tight barriers (classes 4 and 5) in 32 % of the products. This is a strong move toward efficient barriers compared to the findings in 2010. Efficient or tight barriers were found for nearly all food types, which suggests that there are no important technical obstacles against the inclusion of a barrier layer into all bags to protect the food against contamination from the recycled paper board.