Inspection Methods for Snack Foods

Global snack sales totalled $374 billion annually ending March 2014—an increase of 2 percent year-on-year. That’s because more consumers are snacking today than ever before and snacking more frequently. In fact, it’s estimated that on average, 24 percent of our daily calorie intake comes from snacks. With nearly one in four calories consumed outside a meal, the snack is no longer just a treat; it’s become a fourth meal.

As public scrutiny of food manufacturers continues to escalate and consumers increasingly turn to social media to voice complaints, snack processors have become more reliant on food inspection equipment to protect consumers and reduce the risk of brand-damaging product recalls in order to stay ahead of their rivals.

However, many snack applications can prove challenging for traditional product inspection equipment.

Why Are Snacks Such a Challenge to Inspect?
The unique challenges manufacturers face when striving to produce safe and quality-assured snacks can be summarized in the following issues.

Variety of potential contaminants. Often snacks contain a wide variety of ingredients that are all open to different types of contaminants. Fruits, vegetables, and nuts may be contaminated with stones or a piece of wire from the farm, while dairy products can be suspect to metal or plastics from processing.

High salt content of products. Many snacks, such as nuts and potato chips, contain high doses of salt and are conductive. When they pass through a metal detector, they can create a disturbance of the detection field, triggering false rejects. Product temperature and moisture content can also affect a metal detector’s detection sensitivity.

Metal packaging. Metalized film and foil are used to package various snacks, including energy bars and chocolate. Inspecting these products using metal detectors can lead to reductions in the level of achievable sensitivity. In some cases, if the metalized film is especially thick, it’s preferable to inspect products before packing.

Variations in product density. Many snacks, such as bags of trail mix and granola bars, contain high variations in density because of the multitude of ingredients. Finding physical contaminants in these products can prove challenging for traditional X-ray inspection systems as the varying densities create “busy” X-ray images.

Contaminants similar to product. Color and hand sorting are frequently used to remove rocks and other visual defects from loose flow bulk snacks foods, such as almonds, but neither method is entirely accurate as stones are similar in shape and color to the product. Visual inspection methods are also limited to the top layer, which means anything that can’t be seen, won’t be identified or removed.

Quality assurance. Proper portioning and seal integrity are another two major concerns for snack manufacturers. Individual bars and boxes with multiple bars can be underweight, overweight, deformed, or broken. Additionally, during the sealing process, bits of food can get trapped in product seals, creating a faulty seal and causing food spoilage. To overcome such issues, manufacturers have traditionally installed a range of inspection equipment on their production lines, including checkweighers, metal detectors, and vision systems.

Metal Detection vs. X-ray Inspection
Different snacks and packaging types require different product inspection solutions and selecting the right system is crucial to guarantee maximum detection sensitivity and high throughput.

In many cases, there’s only one suitable solution (metal detection or X-ray inspection) and in many others, either technology could be used. Occasions also exist where it may be necessary to install both technologies at different Critical Control Points (CCPs) on the same line.

Metal detection. For cost-effectiveness, metal detectors usually offer the best solution when looking to detect ferrous and non-ferrous metal, stainless steel, and aluminium contaminants. A metal detection search head also takes up less space than an X-ray inspection system. This means that for applications where installation space is limited and metal is the only likely contaminant, a metal detector may be the best option.