Developments in food packaging integrity testing

Harper, Carol; Blakistone, Barbara; Litchfield, J. B.; Morris, Scott

doi:10.1016/s0924-2244(00)89168-2

Cited by 33 publications

(23 citation statements)

References 5 publications

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“…Harper et al (1995) reported that the presence of channel leaks with a diameter of 250 µm and 200 µm was not detected in respectively a burst and a tensile test and therefore did not influence the seal strength. The authors also stated that it is difficult to define the minimum defect dimensions that permit microbial contamination, since this process does not only depend on the dimensions of the defect.…”

Section: Discussionmentioning

confidence: 99%

Detection of seal contamination in heat sealed food packaging based on active infrared thermography

2015

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In the food industry packaging is often applied to protect the product from the environment, assuring quality and safety throughout shelf life if properly performed. Packaging quality depends on the material used and the closure (seal). The material is selected based on the specific needs of the food product to be wrapped. However, proper closure of the package is often harder to achieve. One problem possibly jeopardizing seal quality is the presence of food particles between the seal. Seal contamination can cause a decreased seal strength and thus an increased packaging failure risk. It can also trigger the formation of microchannels through which air and microorganisms can enter and spoil the enclosed food. Therefore, early detection and removal of seal-contaminated packages from the production chain is essential. In this work, a pulsed-type active thermography method using the heat of the sealing bars as an excitation source was studied for detecting seal contamination. The cooling profile of contaminated seals was recorded. The detection performance of four processing methods (based on a single frame, a fit of the cooling profile, pulsed phase thermography and a matched filter) was compared. High resolution digital images served as a reference to quantify contamination. The lowest detection limit (equivalent diameter of 0.63 mm) and the lowest processing time (0.42 s per sample) were obtained for the method based on a single frame. Presumably, practical limitations in the recording stage prevented the added value of active thermography to be fully reflected in this application.

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Section: Discussionmentioning

confidence: 99%

Detection of seal contamination in heat sealed food packaging based on active infrared thermography

2015

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“…Water-filled channels proved harder to detect than airfilled channels, but it was shown that on a conveyor moving at 500mm/s the system could detect air-filled channels much smaller than 50 microns in width. Harper et al (1995) describe the use of light penetration tests to inspect the thickness of the seals, whereby a translucent seal allows more light to pass through if the adhesive is not thick enough to ensure a strong seal. However this is no longer a common cause of seal faults, perhaps due to better quality control during pack manufacturing.…”

Section: Introductionmentioning

confidence: 99%

Polarised light stress analysis and laser scatter imaging for non-contact inspection of heat seals in food trays

Barnes¹,

Dudbridge²,

Duckett³

2012

Journal of Food Engineering

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This paper introduces novel non-contact methods for detecting faults in heat seals of food packages. Two alternative imaging technologies are investigated; laser scatter imaging and polarised light stress images. After segmenting the seal area from the rest of the respective image, a classifier is trained to detect faults in different regions of the seal area using features extracted from the pixels in the respective region. A very large set of candidate features, based on statistical information relating to the colour and texture of each region, is first extracted. Then an adaptive boosting algorithm (AdaBoost) is used to automatically select the best features for discriminating faults from non-faults. With this approach, different features can be selected and optimised for the different imaging methods. In experiments we compare the performance of classifiers trained using features extracted from laser scatter images only, polarised light stress images only, and a combination of both image types. The results show that the polarised light and laser scatter classifiers achieved accuracies of 96% and 90%, respectively, while the combination of both sensors achieved an accuracy of 95%. These figures suggest that both systems have potential for commercial development.

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“…Currently, seal region defects are detected through visual inspection or destructive testing. However, channels smaller than 50 µm in diameter are not clearly visible to the naked eye, and destructive testing is only valuable statistically (9) .…”

Section: Introductionmentioning

confidence: 99%

Real-Time Terahertz Diagnostics for Detecting Microleak Defects in the Seals of Flexible Plastic Packaging

Morita

Dobroiu

Otani

et al. 2007

JAMDSM

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We present a method of detecting production faults in flexible plastic packages using terahertz (THz) radiation. A focused THz beam is scanned along the sealed area of a package, and the transmitted signal is collected. Defect detection is effected through the large difference between the absorption coefficients of plastic and water for water-filled channel defects, and on the refraction index difference between plastic and air for air-filled channel defects owing to reduction of the incident signals into the detector. Compared to previous methods, such as visual and ultrasound inspection, our technique can be applied to optically opaque packages and does not require immersion in a matching liquid. The method was tested on fabricated 10~100-µm diameter water-filled and air-filled channel defects imbedded in polyethylene films. The detection limit (the minimum size of a detectable defect), which depends on the conveying speed, was determined and analyzed. The results show that our system has potential for application in actual-production, real-time, inspection.

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Developments in food packaging integrity testing

Cited by 33 publications

References 5 publications

Detection of seal contamination in heat sealed food packaging based on active infrared thermography

Detection of seal contamination in heat sealed food packaging based on active infrared thermography

Polarised light stress analysis and laser scatter imaging for non-contact inspection of heat seals in food trays

Real-Time Terahertz Diagnostics for Detecting Microleak Defects in the Seals of Flexible Plastic Packaging

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