Freezing and thawing tests indicate that coated unbleached kraft paperboard packaging for the food industry stands up better than other products, Graphic Packaging claims. Wrinkled or deformed packaging on frozen products might lead consumers to believe that the food product has been thawed at some point and then refrozen, compromising food safety.

The company is attempting to boost its market share in the frozen foods industry by attempting to show that its coated unbleached kraft (CUK) carton packaging does not wrinkle or deform as much as solid bleached sulfate (SBS) paperboard under the stresses of changing temperature. The defects are often the result of condensation that occurs due to temperature changes during transport and in the retail freezer case. Moisture absorbed by paperboard can soften and buckle the carton, Graphic Packaging stated in releasing the results of the tests.

Graphic Packaging markets its CUK under the SUS brand name. The tests were conducted by the company itself, with no independent verification available. In the US, Graphic Packaging holds a 25 per cent market share of CUK used for frozen food. This includes a 85 per cent share of all frozen pizza products by weight and 60 per cent of all frozen bakery products. Graphic Packaging is also the number one supplier of CUK in the world. Graphic Packaging says its three-ply construction of SUS folding carton grades enables the product to achieve superior resistance to compression and bulging, with the added benefit of hiding coating flakes in the interior ply so that the back of the board is blemish free.

"SUS is hard-sized to provide good moisture resistance, and natural resins in pine fibers further aid in water resistance," the company stated. The company performed tests to measure resistance to carton deformation by the degree of buckling occurring in the top carton panel after the carton was exposed to a series of freeze and thaw cycles similar to those experienced by the carton as it moves from the filling line through the distribution chain to the retail freezer case.