Detecting leaks in modified atmosphere packaging 277 Table 13.1 Deterioration factors related to critical channel leakages in different packaged foods epic and Ready-to-eat Baked goods Dried goods sterilised meal microbial on, oxidation oxidation moisture 1,3591230-50m chang >13 diameter in package package types and products. That is, how big a leakage can there be without the packed product deteriorating microbiologically or chemically before the use-by date, and how small a leakage should the leak testing method detect (Table In many studies leakages of around 10 um in diameter have been demonstrated. under strict conditions. to cause microbial contamination in model packages- and in commercially processed and packaged aseptic packages ,", The critical leakage size causing accelerated quality deterioration in gas-flushed modified atmosphere packages (MAP)may vary considerabl ly between different products and packaging methods. Small leakages(hole diameter 169um, hole length 3mm)in gas packages have even been reported to retain the quality of packed minced meat steaks better than in intact packages. Other recent studies have, on the other hand, revealed accelerated quality deterioration of raw marinated chicken breast and raw rainbow trout and pizza in gas packages with leakages as small as 30um and 55um(hole length 3mm), respectively. Table 13.1 summarises the most important deterioration factors of different packaged foods and studies concerning critical leakages 13.3 Package leak detection during processing 13.3.1 Methods in use package and seal integrity is widely verified using destructive manual ods, such as a biotest, electrolytic test, dye penetration test and bubble test The major drawbacks of destructive test methods are that it is not possible to check every package produced, and the tests are often laborious. An automated, iable, 100% in-line non-destructive leak test machine allowing testing of every container produced would, therefore, be of interest to companies. This kind of package testing would serve as an immediate process control tool resulting in an overall cost reduction in terms of a reduced number of packagespackage types and products. That is, how big a leakage can there be without the packed product deteriorating microbiologically or chemically before the use-by date, and how small a leakage should the leak testing method detect (Table 13.1). In many studies leakages of around 10 m in diameter have been demonstrated, under strict conditions, to cause microbial contamination in model packages1,2 and in commercially processed and packaged aseptic packages. 3,4,5 The critical leakage size causing accelerated quality deterioration in gas-flushed modified atmosphere packages (MAP) may, however, vary considerably between different products and packaging methods. Small leakages (hole diameter < 169m, hole length 3mm) in gas packages have even been reported to retain the quality of packed minced meat steaks better than in intact packages.6 Other recent studies have, on the other hand, revealed accelerated quality deterioration of raw marinated chicken breast and raw rainbow trout7 and pizza8 in gas packages with leakages as small as 30m and 55m (hole length 3mm), respectively. Table 13.1 summarises the most important deterioration factors of different packaged foods and studies concerning critical leakages. 13.3 Package leak detection during processing 13.3.1 Methods in use Food package and seal integrity is widely verified using destructive manual methods, such as a biotest, electrolytic test, dye penetration test and bubble test. The major drawbacks of destructive test methods are that it is not possible to check every package produced, and the tests are often laborious. An automated, reliable, 100% in-line non-destructive leak test machine allowing testing of every container produced would, therefore, be of interest to companies. This kind of package testing would serve as an immediate process control tool, resulting in an overall cost reduction in terms of a reduced number of packages Table 13.1 Deterioration factors related to critical channel leakages in different packaged foods Aseptic and Ready-to-eat- Baked goods Dried goods sterilised meals foods Most important microbial microbial oxidation, oxidation, deteriorative changes, changes, mould moisture factors oxidation oxidation growth, changes moisture changes Critical leakage 5–25 m1,3,5,9–12 30-50 m 6,12–13 50 m13 > 130 m13 diameter in package Detecting leaks in modified atmosphere packaging 277