Author: David Prieto, Applications Specialist at Thermo Fisher Scientific
In the food industry, advanced technologies are used during production and packaging to detect foreign objects and identify weight irregularities. These inspection systems help ensure product quality and safety.
Metal detectors are specifically for metal contamination, whereas X-ray systems detect a wide range of foreign materials, both metallic and non-metallic. These include bone, glass, stone, and more. Accompanying checkweighers ensure product consistency and regulatory compliance.
These procedures are vital for safeguarding consumer health, protecting brand reputation, and boosting operational efficiency by preventing contaminated or defective products from reaching the market.
Product Inspection Technologies
Metal Detectors
Metal detectors can identify ferrous, non-ferrous, and stainless-steel foreign objects. They are an excellent choice for examining a broad variety of food goods, including frozen meals and packaged snacks.
Metal detectors measure the magnetic and conductive qualities of the packaged food under inspection. Each inspected product contains intrinsic magnetic and conductive signals known as product effect, which vary depending on the type of product and packaging. For example, dry cereal has a low product effect, whereas wet foods such as canned soups have a significantly higher product effect due to their moisture and salt content.
A successful metal detector measurement ignores the product effect and responds solely to signals from impurities.
When a metal detector identifies a contaminant, it detects changes in the product’s magnetic and conductive signals. This triggers the system to either activate a reject mechanism, or halt the production line, depending on the chosen operational setup.
In food manufacturing, the usual process involves processing incoming ingredients, combining, cooking, molding, packaging, and storing. Contaminants such as debris from old blending blades or loose bolts and nuts can be accidentally introduced at any point.
Metal detectors can be used at various stages of the food production process to reduce contamination risk and achieve Hazard Analysis and Critical Control Point (HACCP) objectives for food safety compliance, whether during incoming raw material inspection or final packaging.
However, metal detectors are not compatible with metalized film wrapping due to the "package effect." Packages with these film pouches or metal containers can cause false alarms and interfere with the detection of contaminants because the signal produced by these packages overpowers the signal of tiny metal fragments.
As a result, products with this packaging need to be examined with X-ray inspection systems for reliable food safety. In addition, environmental conditions can have an impact on metal detector performance during product screening.
Magnetic fields from surrounding equipment, electrical interference from other gear, and power supply variations can all affect the detector's sensitivity and accuracy.
Finally, temperature and humidity conditions might affect the stability of the metal detector's electrical components, resulting in inconsistent findings.
To mitigate these issues, metal detectors should be installed in controlled surroundings, shielded from extraneous electromagnetic interference, and regularly calibrated to ensure dependable performance.
X-Ray Inspection Systems
X-ray inspection systems generate detailed images of a product’s contents, enabling the detection of metallic and non-metallic contaminants such as glass and rubber. They can also identify broken food items and missing components within a package.
Unlike metal detectors, X-ray inspection is unaffected by product or package effects, making it appropriate for a wider range of items and packaging materials, including those made of metalized film or aluminum foil trays.
Food inspection systems. Image Credit: Thermo Fisher Scientific – Production Process & Analytics
Like metal detectors, X-ray screening can be done at all phases of the manufacturing process, from entering ingredients to final case packaging.
As food products are intended to provide a comprehensive nutritional diet, they mostly contain a wide variety of nutrients and vitamins. While this variety is a positive, it can also increase the possibility of diverse contaminants being introduced at any moment, from raw ingredients to final processing.
For example, imported meats can have metal shavings from previous processing stages conducted by the supplier, and vegetable picking may mistakenly include stones and soil particles that were overlooked before processing.
X-ray systems can be used in a wide range of applications, but they have limitations:
A typical constraint is the product's density and thickness, which can impede X-rays and prevent the identification of very low-density impurities like thin glass, small glass shards, wood pieces, and thin plastics, to mention a few.
For example, if a product has the same density as a little piece of shattered glass, the X-ray equipment may be unable to identify the glass impurity. Inconsistencies in packing shape might also impair the sensitivity and accuracy of the detection procedure.
Or in a snack bag, the product distribution can move inside, and this can result in false rejects due to variations in package shape. High-speed manufacturing lines can also have an impact on the resolution and accuracy of X-ray inspection due to shorter exposure times and motion blur in the image.
As a result, if the conveyor speed varies significantly, the same product may produce various detection results.
Understanding these variations and limitations is essential for selecting the best X-ray systems for reliable product inspection.
Checkweighers
Checkweighing is an additional food quality inspection method for foreign item identification. It ensures that the weight reported on the product label corresponds to the actual weight of the package.
This prevents food manufacturers from underfilling packages, which can result in significant regulatory fines, or overfilling, which results in superfluous product giveaways.
Checkweighers are often placed after the portioning and packaging steps, with a final weight check often performed after case packing to ensure that the correct weight and packages were distributed. Some checkweighers also offer feedback to operators on the filling process.
For example, a manufacturer may specify a precise fill level or volume for a package, but with time, the filler may diverge from this target, resulting in overfill or underfill.
A checkweigher's capacity to assess data patterns, display how closely each fill coincides with the desired weight, and provide real-time feedback to the filling machine aids in production cost control. This automated process enhances efficiency while ensuring consistent product weight over time.
However, checkweighers can be affected by environmental factors such as vibrations, temperature fluctuations, humidity, and airflow, all of which can reduce measurement accuracy. Product buildup within the system can also pose challenges, requiring appropriate measures to maintain reliability, such as an appropriate cleaning operation.
Quality Assurance and Regulatory Compliance
A global industry, the food business requires appropriate regulation. Each country or region has its own regulatory authorities that ensure proper food safety protocols and public safety. A number of key organisations help uphold food safety standards around the world.
In the United States, the Food and Drug Administration (FDA) plays a central role, while in Europe, this responsibility falls to the European Food Safety Authority (EFSA). These bodies enforce strict regulations that manufacturers must follow to operate in their respective regions.
Among the notable global standards is ISO 22000, developed by the International Organization for Standardization. This widely recognized framework sets out the requirements for an effective food safety management system.
They set the requirements for a food safety management system, in which an organization in the food chain must demonstrate its ability to handle food safety hazards so that food is safe for human consumption.1
The Hazard Analysis and Critical Control Point (HACCP) method is a systematic strategy used in the food industry to detect, assess, and control possible food safety hazards.2
These procedures help ensure food products are safe for consumption and meet required production standards. Product inspection technologies offer valuable support to the food industry by safeguarding product quality and protecting brand reputation.
They also help companies to track short- and long-term data, making it easier to manage audits and maintain detailed production records.
Future Trends and Innovations
Product inspection is constantly improving its systems to ensure industry and public safety. A noteworthy future trend is the combination of X-ray technology and Artificial Intelligence (AI) for sophisticated applications.
AI and X-ray systems are combined by applying modern algorithms and machine learning approaches to improve the identification and analysis of faults and irregularities in food goods and assist with difficult computations and picture processing.
Some applications include determining a product's correct orientation within its packaging and categorizing/sorting different portions of a product. In addition, advances in X-ray image inspection are being made to detect inconsistencies in images and examine segmented sections within a package for better analysis.
Greyscale imaging is being increasingly used in visual tools to assess product quality in stacked formats.
Conclusion
These product inspection technologies are essential for ensuring food safety and quality. Each plays a key role in detecting contaminants, verifying product weight, and enhancing overall production standards.
By upholding strict safety protocols, these systems support regulatory compliance and help build consumer trust.
References
- ISO (2018). ISO 22000:2018 Food safety management systems — Requirements for any organization in the food chain. (online) ISO. Available at: https://www.iso.org/standard/65464.html.
- FDA (2022). HACCP principles & application guidelines. (online) U.S. Food and Drug Administration. Available at: https://www.fda.gov/food/hazard-analysis-critical-control-point-haccp/haccp-principles-application-guidelines.
This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific – Production Process & Analytics.
For more information on this source, please visit Thermo Fisher Scientific – Production Process & Analytics.