Leak detection in polyethylene terephthalate bottles filled with water and pulped and unpulped orange juice using a vacuum decay system

Abstract

This research evaluated an offline vacuum decay leak detection system for 1,775-ml polyethylene terephthalate (PET) bottles. These bottles were filled with water and pulped and unpulped orange juice and induction sealed with an aluminum liner and an outer 38-mm continuous thread polypropylene cap. The objectives of this study were to evaluate (i) minimum leak size sensitivity of the instrument; (ii) ability to identify weak but nonleaking seals; (iii) effect of varying fill heights on the equipment's sensitivity; and (iv) percentage of false-positive and negative results likely to be obtained during a normal test run. To meet these objectives, leaks 5, 10, 15, 20, 30, 40, and 50 μm were created in the PET bottles. A second set of bottles was induction sealed at high voltage and 1, 1.5, 2, 2.5, 3, 3.5, and 4 s of dwell time. A third set of bottles with good seals was filled with differing headspace measurements of brimful, 1, 2, 3, 4, and 5 cm. After optimizing the equipment, leak tests on random sets of leaking and nonleaking bottles showed 0.0% false-positive and 0.0% negative identifications. Results showed 5-μm minimum leak size detection for bottles filled with all products. Optimum seal conditions were >2 but <3 s at high voltage. Product fill heights >2 to ≤3 cm did not affect the efficiency of the equipment. These results show that this vacuum decay system has potential for use in identifying leaks in PET bottles used for food packaging. Copyright ©, International Association for Food Protection.