Challenges in Leak Detection and Seal Integrity in Emerging Packaging Materials

Abstract

Leak tightness and seal integrity are critical quality parameters in food and non-food packaging, directly affecting shelf life, product safety and sustainability. The transition towards Packaging and Packaging Waste Regulation (PPWR) compliant packaging materials, such as mono-material structures and reduced barrier multilayers, introduces new challenges for reliable leak detection, particularly for microleaks, complex package geometries, liquid products and low headspace or vacuum packaging. The main objective of this study is to research the applicability, sensitivity and limitations of existing online and offline leak detection and seal integrity techniques for both conventional and PPWR compliant packaging systems. The study consists of three complementary research parts: (i) a Design of Experiments (DOE) was performed on laboratory produced OPA/CPP pouches to systematically assess the influence of leak size, leak location and the presence of multiple leaks introduced using three different methods. Pouches (two different sizes) with and without leaks were analysed using non-destructive vacuum decay testing. (ii) In parallel, a selection of over ten different commercial packaging concepts, combining different materials, container types and contents, were evaluated using non-destructive leak detection techniques, namely vacuum decay and/or carbon dioxide (CO2)-based leak detection. (iii) In addition, the influence of leaks on oxygen ingress was investigated using a fluorescence oxygen analyser in specific case studies. The primary findings show that leak detectability strongly depends on leak size as well as the method used for the creation of leaks, leak location, package geometry, internal gas composition and product characteristics. The results further demonstrate that no single leak detection technique is universally applicable. Vacuum decay methods perform well for packages with sufficient headspace but are unsuitable for liquid filled, vacuum packed, very small multiple cavities or large liner bags. CO2-based techniques are effective for modified atmosphere packaging but cannot be applied once gas has escaped or when CO2 is absent. Many findings are confirmed in the case studies, which also indicate that microleaks significantly affect oxygen ingress and product spoilage, while mitigation strategies such as oxygen scavengers may partially compensate for very small leaks but not for larger defects. This work contributes new insights by systematically linking packaging design, material choice and leak detection performance with regard to the transition towards PPWR compliant packaging. Its potential impact lies in supporting packaging developers, quality managers and equipment suppliers in selecting appropriate detection strategies, defining efficient sampling approaches and reducing the risk of false conclusions.