July 24, 2024

Hyperspectral seal inspection system easily detects contamination in rigid plastic packaging

Belgian seal inspection specialist Engilico has introduced a new system for in-line verification of the integrity of hermetically sealed plastic rigid packaging containing food.

In addition to the established SealScope™ automated system for seal quality control of flexible plastic packaging, the company has introduced a new system, HyperScope™, for checking the seals on rigid trays, pots and other thermoformed packages sealed with plastic film, even when printed. Product in seal often causes issues for standard vision systems, as there might not be enough contrast between the plastic film and the contamination. In case of packaging with a printed top film, often used for more luxury products, the contamination can even not be seen.

Engilico’s new HyperScope in-line seal quality inspection machine for rigid plastic packaging

Engilico has solved the problem by harnessing the power of hyperspectral imaging, which analyses a wider light spectrum than just the visible range to include near-infrared frequencies. Infrared waves are able to penetrate plastic film and as different materials react uniquely to infrared light, they can be reliably detected based on their specific properties of transmission, reflection and absorption of these wavelengths. The spectrum of each pixel in the acquired image is analysed to provide information about chemical composition. Any undesired materials in the plastic seal area such as meat, fat or oil can be detected in high contrast, even through an opaque top film, and is shown on the control screen in a different colour.

It is noteworthy that hyperspectral imaging is perfect for this quality control process. Shorter electromagnetic wavelengths from the other side of the visible spectrum, such as X-rays, are good for seeing metal parts, for example, but have too much penetrating power to resolve materials whose density difference is small, such as plastic and food.

Typical applications are 100% inspection of trays containing meat, cheese, fruits, ready meals and snacks. Investment in an automated quality control system directly integrated at the end of a food production line pays for itself quickly, as it minimises the production of faulty product and automatically rejects any packages that have passed through with an unsatisfactory seal. Additionally, the costs associated with line stoppage, manual re-packaging, food wastage and machine cleaning are avoided.

Failure to detect contamination in a seal is a serious issue, as if the package finds its way onto a supermarket shelf, air ingress and leakage would render the consumption date advice on the label irrelevant. Even worse, it could result in health issues for the consumer. In either case, an expensive product recall and potential brand damage are likely.

Engilico’s hyperspectral system is installed over an existing or its own conveyor belt and inspects every individual package at a rate of up to 160 per minute. HyperScope instantly recognises package orientation, processes the image and analyses the seal quality, the information being displayed on an operator-friendly touch screen. All production-related data such as product type, number of good/bad packages, date and time is saved for subsequent production quality analysis. In general, in-line seal inspection enables customers to realise better packaging quality, higher packaging productivity, end-of-line automation and a reduction in manual inspection.

A point along the seal with contamination has a different hyperspectral profile, indicating where the plastic package is compromised and leakage is likely to occur. It is shown on-screen as a high contrast area in a different colour