Reliability of nondestructive pressure differential leakage testers using semi-rigid retort trays

The sensitivity and reliability of two commercial nondestructive leak testers were studied using commercially manufactured semi-rigid retort trays with headspace filled with spaghetti in meat sauce. Leak testing was based either on detection of rise of pressure in a test chamber or on fall of pressure in the package during mechanical compression.
Evaluated test variables included package leakage (holes of 15 to 60 μm in diameter), retorting, test pressure and pressurizing tool. The increased pressure differential increased the sensitivity of the method detecting external rise of pressure in particular, whereas blockage of the holes during retorting decreased the capability of the evaluated techniques to detect leakages.
Neither of the test methods could detect threshold leakage of 10 μm in diameter for bacterial penetration determined earlier with similar retort trays. The leakage detection limits for the methods detecting external rise of pressure and the internal fall of pressure were leakages larger than 32 μm and 59 μm in diameter, respectively.
Leak testing did not affect the integrity of intact packages.