Evaluation of defects in the seal region of food packages using the ultrasonic contrast descriptor, ΔBAI

Abstract

A rapid, dependable method of on-line package inspection will allow wider implementation of energy- and material-efficient retortable pouches and trays, by reducing inspection costs. To evaluate high-frequency ultrasonic imaging as a sensing method, the 17·3 MHz ultrasonic pulse-echo Backscattered Amplitude Integral (BAI) method was used to visualize and evaluate major defects (channels and product inclusions, which compromise the seal integrity and must be reliably inspected) in the seal area of flexible food packages. The focus of this study was to evaluate the image contrast, denoted ΔBAI, for various packaging materials, defect types and sizes. Channel (6–100 µm in diameter) and inclusion defects (strands of mouse tail tendons, 20–150 µm) were created in the seal area of all-plastic and foil-containing packaging films. It has been shown that there is a direct relationship between the defect size and ΔBAI value, and that different defect types and packaging materials have a significant impact on the ΔBAI value. The utility of ΔBAI for detecting defects makes it a useful and reliable sensing method for package inspection. Copyright © 1999 John Wiley & Sons, Ltd.