5 steps for food packaging safety with X-ray inspection

Feb. 5, 2016

Quality checks to detect physical contaminants in retail packaged products can prove challenging, even with X-ray inspection systems specifically designed to inspect food packaging.

Food manufacturers increasingly rely on product inspection equipment to protect consumers, safeguard their brand reputations, reduce the risk of costly product recalls, and comply with safety regulations and retailer guidelines. However, performing quality checks and detecting physical contaminants in retail packaged products can prove challenging, even with X-ray inspection systems specifically designed to inspect food packaging.

Below is a five-point checklist to help manufacturers ensure the safety and integrity of products packaged in cartons and boxes, foil pouches, flow-wraps, doypacks, composite cartons and tubes, metal cans, and plastic and glass containers.

Step 1: Understand X-ray inspection regulations

To satisfy the requirements of food regulations and standards, manufacturers must understand what they entail and which ones apply to their organization.

Choose X-ray equipment that can help manufacturers adhere to a diligent Hazard Analysis and Critical Control Points (HACCP) program and that can comply with individual retailers’ codes of practice. Also be sure to follow Global Food Safety Initiative (GFSI) recognized schemes:

  • International Featured Standard (IFS)
  • ISO 22000:2005
  • Be sure to select an X-ray supplier that has knowledge of global quality standards, regional differences and industry variations.

Step 2: Focus on the product

With an understanding of relevant regulations and standards, manufacturers should turn their attention to the nature of their product.

X-ray inspection systems can detect glass shards, metal fragments, mineral stone, calcified bone, and some high-density plastic and rubber compounds within a variety of retail packaged applications. What’s more, neither foil nor metallized film packaging affect the sensitivity of contamination detection.

However, different foods and packaging types require different solutions, and selecting the right X-ray inspection food packaging equipment is fundamental to guarantee maximum detection sensitivity.

Cartons, plastic containers and more

Low-density packaging, such as cartons, plastic containers, composite cans and tubes, and doypacks, is used for a wide variety of food. Typical applications include snacks, beverages, yogurts, ready-made meals and cereals.

Low-density packaging presents no challenges to detection sensitivity. The packaging material absorbs minimum X-rays due to its thin material type. However, physical dimensions of the container can be limiting. Generally, the larger the container’s diameter, the greater the impact will be on the detection levels. An X-ray system with a single horizontal beam is best for detecting physical contaminants and quality defects in products packaged in low-density packaging.

X-ray inspection systems can detect glass shards, metal fragments, mineral stone, calcified bone, and some high-density plastic and rubber compounds within retail packaged applications.

Metal cans

Metal cans, classed as medium-density containers, are used widely in the food industry to package beverages, fish and seafood, fruit and vegetables, infant milk powders, meat, ready-made meals, soup, and pet food. The sensitivity of contaminant detection in metal cans can be affected by product conditioning/presentation, the side-wall ribbing of the can, the ring pull and the overall size of the can.

Metal cans are more challenging to inspect than low-density containers because the packaging itself is denser and absorbs more X-rays. In addition, they usually contain higher density products and can have a larger diameter so more product is in the path of the X-ray beam.

However, the toughest challenge is detecting small contaminants located on the base or side walls of cans, where the profile of the packaging creates inspection blind spots. Still, a horizontal split-beam X-ray system improves the probability of detecting these small contaminants because it images every can twice. Each image represents a different viewing angle, increasing coverage inside the container and the probability of detection.

Glass jars/bottles

Glass containers are used to package a wide variety of applications, including beverages, condiments, meat, confectionery, fish and seafood, fruit and vegetables, infant feeding products, and ready-made meals.

Despite its popularity, glass packaging poses a significant safety risk, and the effects of glass-in-glass contamination can be highly damaging. Moreover, glass containers are notoriously challenging to inspect because the primary contaminant is glass. It has the same material and density as the packaging, and the density of the packaging material is problematic. In addition, the base, sidewalls and neck can all cause blind spots, potentially masking dangerous contaminants.

Innovations in technology mean that X-ray container inspection systems now inspect products in glass containers all-round. Either a combination beam X-ray system or a system with an angled single X-ray beam can achieve optimal glass-in-glass detection. Other solutions can detect and remove glass contaminants within glass packages at high throughput speeds without disrupting production lines or processes.

Step 3: Increase risk awareness

Good manufacturing practices (GMP), such as those outlined in a HACCP program, should always be in place.

A comprehensive manufacturer audit involves identifying any manufacturing risks and incorporating means to mitigate these risks when identified, or implementing corrective actions to manage them. Once manufacturers have completed an initial risk assessment, they can more easily ascertain which X-ray system is best for their risk control requirements and where on the production line it should be installed.

To ensure the highest levels of food safety and integrity, X-ray machines for packaged products are typically located at the end of the production line for final inspection before dispatch. Then, when the production process is over, the packaging is sealed, and no further contaminants can enter the product. Installing them at the end of the production line also allows food manufacturers to perform simultaneous quality control checks.

X-ray inspection systems can ensure food safety and quality and help compliance with industry standards that include HACCP, the GFSI and GMP.

Step 4: Enhance X-ray inspection productivity

In addition to ensuring food is safe to consume, additional features can be selected on X-ray systems to increase productivity and minimize downtime.

Modern X-ray systems can perform a number of food industry quality checks in addition to contamination detection in a single pass at high line speeds. These product integrity checks include measuring gross and zoned mass; measuring head space; counting components; monitoring overall and zoned fill levels; checking for missing or damaged products and packaging; inspecting seal integrity; and detecting flavoring agglomerates.

Step 5: Trust the experts

Purchasing the right X-ray inspection equipment can initially appear daunting. With food safety regulations frequently changing and becoming more stringent, though, manufacturers face increasing pressure to ensure product safety and traceability.

To avoid confusion, manufacturers should look for an equipment provider with expertise to consult on optimum systems and provide the best X-ray inspection equipment on the market.


Manufacturers are increasingly relying on X-ray inspection systems to ensure food safety and quality in a variety of retail packaging formats, as well as to help them comply with industry standards, including HACCP, the GFSI and GMP.

However, selecting the right X-ray inspection food packaging equipment for a specific application and packaging type is crucial to guarantee maximum detection sensitivity and high throughputs.

Daniela Verhaeg is a marketing manager with Mettler-Toledo. She may be reached at [email protected].

Mettler-Toledo Safeline is a supplier of metal detection and X-ray inspection solutions for the food, beverage and pharmaceutical industries. Together with Garvens Checkweighing, CI-Vision and Pharmacontrol Electronic GmbH (PCE), Mettler-Toledo Safeline forms the Product Inspection division of Mettler-Toledo.