Development of fill product with aggressive properties for accelerated storage tests in Tetra Recart

Abstract

Tetra Recart (TRC) is a multilayer laminate paperboard package used to package foods such as tomatoes, beans, vegetables and sauces. Some “aggressive” food products interact with the inside of the package material and make it difficult to guarantee the quality of the food during the whole shelf life of the product. Products with pH below 4 and Cl− content above 1% are regarded as “aggressive” and are not packed in the TRC standard material. In this thesis work, a fill product mimicking aggressive food products has been developed. The goal was to obtain the same interaction patterns as given by aggressive food products, but eight times as fast, in order to use the fill product in accelerated storage tests in the development of new TRC materials. The work included the development of a model for corrosion development caused by aggressive products, the design of the fill product, packaging, and opening and evaluation of the packages. As well as evaluating the effects of different concentrations of acids, salts, fat and fatty acid together with an emulsifier, the influence of different storage temperatures on delamination of the inside polymer coating and corrosion of aluminium was evaluated. Delamination of the inside polymer was crucial for an accelerated development of corrosion of the aluminium foil. The presence of free fatty acids and an elevated storage temperature were necessary factors for delamination to occur. A high Cl− content seemed to be more important than a low pH in terms of aggressiveness of a product. The most well suited test product to use in accelerated storage tests of aggressive products in TRC had a pH of 2.49 and a Cl− content of 7.71 %. It was stored at 35°C and contained 40 ppm free fatty acids. This product gave accelerated corrosion, and showed good compliance with the developed model for corrosion development. The composition of the test product is well outside the range for human food, i.e. the food package interactions described in this report would not occur to the same extent with products suitable for human consumption.