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

A rapid, dependable method of on-line package inspection will allow wider i mplementation of energy- and material-efficient retortable pouches and tray s, by reducing inspection costs. To evaluate high-frequency ultrasonic imag ing as a sensing method, the 17.3 MHz ultrasonic pulse-echo Backscattered A mplitude Integral (BAI) method was used to visualize and evaluate major def ects (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 Delta BAI, for various packaging materials, defect types and sizes. Channel (6-10 0 mu m in diameter) and inclusion defects (strands of mouse tail tendons, 2 0-150 mu m) were created in the seal area of all-plastic and foil-containin g packaging films. It has been shown that there is a direct relationship be tween the defect size and Delta BAI value, and that different defect types and packaging materials have a significant impact on the Delta BAI value. T he utility of Delta BAI for detecting defects makes it a useful and reliabl e sensing method for package inspection. Copyright (C) 1999 John Wiley & So ns, Ltd.