Understanding the correlation between molecular structure of chilled dairy creams and the risk of environmental stress cracking in Tetra Pak® carton packages

Sammanfattning: Multilayer food packaging are lined with an inner layer of plastic and has excellent barrier properties. However, plastics lose their mechanical properties after being exposed to certain conditions; the combination of factors generates failures in the material such as the appearance of cracks, this phenomenon is known as environmental stress cracking (ESC). Tetra Pak® has been interested in research on the formation of cracks in the bottom. Previous investigations have been carried out on packaging such as Tetra Top® and products with a high fat content as dairy creams and it was found that in some cases there were “aggressive” agent that accelerate the formation of cracks and increase the risk of ESC. This research focused on the study of chilled dairy creams, investigating the effect of unit operations in the production process (heat treatment: direct or indirect, and homogenization: downstream, upstream, and no apply) that could substantially influence the molecular structure and physicochemical properties of the final dairy cream. Therefore, three different phases were developed in the project; the first was the production of five batches of chilled dairy cream using a lab mini-UHT (with 5 different formulations). In the second, physical and chemical analyses of the dairy cream batches, and in the third phase, the indicative tests of food package interaction as the main objective of investigating the ESC. It is important to note that these tests were carried out on a laboratory scale, the purpose was to simulate the process conditions that occur in the dairy industry, but there are more factors to control, such as the flow speed, the homogeneity of the raw materials, among many other variables that are difficult to control. Nevertheless, the objective of finding significant differences in the final product depending on the applied process was fulfilled