Food Safety Inspection FAQs

Product effect is the disruption, caused by a combination of typical product attributes, to a metal detector’s ability to distinguish between metal contaminants and false signals generated by the product itself. The product effect can occur when a product has a conductive property which affects the magnetic field generated by the food metal detector. This is typically found in product environments that have high salt and high moisture contents. For example, warm bread coming out of the oven, coupled with its salt content, tends to have a high product effect. Such traits adversely impact the metal detector’s ability to distinguish between actual non-ferrous metal contaminants and the signals generated by the bread itself. This is further complicated by the varying densities, air bubbles, and other physical characteristics of each loaf, since no two are exactly the same. (There also are variations between bread types.) In these situations, food X-ray inspection equipment will produce significantly better results since product effect is not a factor.

The ideal time to run a loaf of bread through the X-ray equipment is prior to bagging. Bread is typically conveyed through the X-ray machine with its longest dimension leading. At the point of entry, there is a lead shielding curtain, which sometimes causes the loaf to roll on its side as it passes through. This is not problematic for the X-ray machine; however, incorrect orientation can negatively impact the bagging operation that immediately follows. On specialty bread lines, where volumes and production speeds are slower, loaves can be positioned so that the short dimension leads. Introducing the loaf to the machine in that orientation minimizes the curtain’s contact with the bread, thereby preventing loaf roll-over.

Since bagel and pretzel products are typically sold in multiples, the objective of inspection is both contamination detection and verification of count. Additionally, pieces can break off during the production process. Food X-ray inspection is the best technology because it can be deployed to spot broken pieces of pretzels or missing components (of multipack counts).

The recommended food safety inspection machinery type for cakes and pies is dependent on the packaging materials used. Since most pies are in aluminum foil pans, food metal detectors can be useful to examine ingredients and dough. However, after the pie has been placed into the pan and/or folding carton, X-ray inspection should be used. Cakes also sometimes rely on aluminum foil pans, folding cartons and metalized film, so the inspection solution recommended is also X-ray.

Food metal detectors work extremely well with frozen baked goods which no longer have the level of product effect that “just out of the oven” versions do. The challenge is to make sure that the freezer is efficient and is holding the product at the correct temperature. If a product isn’t completely frozen, its unfrozen center will have a tendency to look like a piece of metal to the detector.

In addition, many cake and pie products are frozen immediately after production, so some bakers choose to inspect them after the items are case packed, using food X-ray inspection that can accommodate the case size.

Although most snack foods don’t have the product effect issues found in baked items, spotting contaminants is challenged by the packaging material of choice. The majority of snack foods marketed today are packaged in metalized film which is formed into a bag via a form-fill-seal (f/f/s) machine or flow wrapper. This means that these packages are not good candidates for metal detectors. Rejection of products in the food metal detector equipment is also challenging because packages tend to be small.  With these process and material obstacles in place, food X-ray inspection equipment is the ideal solution to address snack food inspection challenges.

In the case of bars and other similar snack products, food X-ray inspection can be used for spotting missing or broken pieces.

Every detection system has a probability of an escape. The type of metal, its shape, position, product effect, etc., all are factors in detecting a metal contaminant. Multiscan technology provides unmatched sensitivity and the highest probability of finding ferrous, non-ferrous, and stainless steel metal contaminants in challenging applications such as dairy, meat, poultry, bread, and other applications with high product effect. Multiscan reduces the number of escapes significantly, because it’s like having five metal detectors back-to-back running the same package at different frequencies.

Checkweighers are a critical component of most packaging lines. Inclusion of enough product to make the weight specified on the label is an important issue with regulatory and brand equity implications. However, it is also critical that expensive ingredients are not being given away in the form of overfills. Additionally, with products that have tight packaging tolerances, such as bars that need to fit in a wrapper with specific dimensions, products that exceed size tolerances can very quickly shut down a production line. Food checkweighers can signal production on the fly to make a fast adjustment to make sure that the specifications are being met.

There are several points in the baked goods/snack foods production process that benefit from food safety inspection (metal detectors, X-ray inspection) and checkweighing technology. Here are some examples:

• Incoming ingredients. Most of the larger bakers demand that their vendors meet specific HACCP (Hazard Analysis Critical Control Point) objectives. They may require that metal detectors be used, provide proof of inspection, etc. Even with those methodologies in place, some will also inspect incoming ingredients. Typical incoming inspection consists of drop through and bulk flow metal detectors.

• Dough stage. Before the product is baked or otherwise processed, this is an ideal location to conduct upstream inspection. Metal detectors are the equipment of choice because metal-based packaging is not part of the process at this stage. Bar products are another example of candidates for pre-packaging inspection. They can be examined right after sheeting, or after the individual bars are cut, or before the product goes into the wrapper. Alternatively, they can also be inspected after packaging.

• After baking/before packaging. The inspection equipment type will depend on the product type and whether or not its formulation creates a “product effect.” Warm, moist, high salt content products such as breads are more suited toward X-ray equipment, while metal detectors perform well with typically-inert snack foods. Checkweighers can also be located at this stage to make sure that the product weight falls within the minimum/maximum specifications and will not create problems (such as line stoppages due to oversized portions) at the packaging stage. Checkweighers can also be used to confirm that all of the late-stage filling components, such as icing and other toppings, have been properly dispensed.

• After packaging. The recommended inspection equipment type is dependent on the packaging material or combination of materials that have been selected for this product. Metal components such as aluminum foil trays or metalized firm structures are much more suited to X-ray inspection. Flexible materials without a metal component, paperboard folding cartons, and/or a combination of the two, work very well with metal detectors. Checkweighers are frequently located at this stage of the operation.

• After case packing. Some bakers or processors prefer to inspect after the final packaging stage of case packing. This is typically done via X-ray inspection, provided that the unit is large enough to accommodate a case. In addition to inspection, the X-ray system’s ability to detect missing pieces will help ensure that the specified count has been loaded into the case. In certain situations, especially when X-ray inspection is not included at the end of the line, checkweighers are placed here to help ensure that the proper number of packages are contained inside the case.

These are the four best places in the dairy production process that benefit from inspection (metal detection, X-ray inspection, and checkweighing):

• Incoming ingredients. Drop through and bulk flow metal detectors are ideal choices for dairies wanting to inspect incoming ingredients such as powders, fruits, or nuts before incorporating them into the finished product.

• Liquid flow. Metal detectors work in pipeline applications for novelties and other liquid-fill products.

• After filling/packaging. The dairy product inspection equipment type will depend on the product type and its potential for product effect. Since many dairy products have high moisture content, they are more suited for X-ray inspection at this stage. Checkweighers can be located here to make sure that the product weight is within minimum/maximum specifications with an option for electronic real-time feedback to the filler to adjust production on the fly.

• After case packing. Some dairies can benefit from inspection after final packaging or in-case packing. This is typically done via X-ray inspection if the case is less than 8” high and the machine’s aperture is large enough to accommodate a case. The X-ray system can be used to confirm that the specified count is loaded into the case. In certain situations, checkweighers can perform this latter function.

For dairy products in cartons, cans, bottles, or pouches, a chain checkweigher offers line speeds up to 700 packages per minute. It is appropriate for both dry and wet environments.

Pipeline X-ray inspection is the best methodology for dairy inspection, as formulations can be complex and frequently modified. These changes can negatively affect metal detector performance due to varying product effect.

Many yogurt products use an aluminum foil or metalized lid to aid freshness and prevent tampering, making them best suited to X-ray inspection.

To verify that the stick is in the right position, or is even in the package, an X-ray system is ideally suited for the task. 

X-ray equipment may be the better choice for pre-weighed packaged cheese in single-serve, sliced, and shredded options. In addition to detecting foreign objects, X-ray systems can measure slice thickness and count the number of individually wrapped cheese sticks. X-ray inspection is also effective for Swiss cheese and other non-uniform products.

Like sour cream and other ‘fresh dairy’ products, cottage cheese is considered conductive, generating a product effect. Because of this, X-ray inspection is a better option than metal detection. Also, checkweighers are effective for these product lines in helping to ensure that profits are not given away by exceeding the label weight, or that the package contains less product than the label indicates.

Like cottage cheese and other ‘fresh dairy’ products, sour cream is considered conductive, generating a product effect. Because of this, X-ray inspection is a better option than metal detection. Also, checkweighers are effective for these product lines in helping to ensure that profits are not given away by exceeding the label weight, or that the package contains less product than the label indicates.

X-ray inspection is best to detect contaminants, but also to help ensure that components such as measuring scoops are present. Drop-through metal detectors, which have excellent sensitivity, are also used for this application.

X-ray inspection of packaged and bulk food products is proven to be extremely safe. There is no documented evidence of adverse health effects of X-rays on equipment operators, the food products that travel through the equipment, or the ultimate consumers of those products.

Product effect is the disruption, caused by a combination of typical product attributes, to a metal detector’s ability to distinguish between metal contaminants and false signals generated by the product itself. The product effect can occur when a product has a conductive property which affects the magnetic field generated by the food metal detector. This is typically found in product environments that have high salt and high moisture contents. For example, wet cat food will show significantly more product effect due to its high moisture and salt content. Such traits adversely impact the metal detector’s ability to distinguish between actual non-ferrous metal contaminants and the signals generated by the cat food itself. In these situations, industrial X-ray inspection equipment will produce significantly better results since product effect is not a factor.

There are several points in the pet food production process that benefit from food safety inspection (metal detectors, X-ray inspection) and checkweighing technology. Here are some examples:

• Incoming ingredients. Large pet food producers may require that their vendors meet specific HACCP (Hazard Analysis Critical Control Point) objectives and provide proof of inspection. Even with those methodologies in place, some will also inspect incoming ingredients. Typical incoming inspection consists of drop through and bulk flow metal detectors.

• After mixing/rendering. Processing equipment such as an industrial blender or mixer will age over time and potentially introduce small particles or shavings of metal into the product being processed. It is important to position inspection equipment after this process equipment to catch any contaminants as early in production as possible, so they do not affect final product quality nor damage equipment further downstream. The inspection equipment type will depend on the product type and whether its formulation creates a product effect. Wet or moist pet food products are more suited toward X-ray equipment, while metal detectors perform well with dry or kibble type pet food products.

• After filling/packing. The recommended inspection equipment type is dependent on the packaging material or combination of materials that have been selected for this product. Metal components such as aluminum foil trays, metal cans, aluminum foil bags or metalized firm structures are much more suited to X-ray inspection. Flexible materials without a metal component, paperboard folding cartons, bags or pouches work very well with either metal detectors or X-ray inspection systems. At this stage, checkweighers are frequently used in combination with a metal detector or X-ray inspection system to help ensure product weight matches information printed on the product label.

• After case packing. After case packing is another good inspection point as this is the last stop before the finished products leave the facility. The recommended inspection equipment type is dependent on the packaging material of the individual product. This is typically done via X-ray inspection. In addition to contaminant detection, the X-ray system’s ability to detect missing pieces will help ensure that the specified count has been loaded into the case. In certain situations, especially when X-ray inspection is not included at the end of the line, checkweighers are placed here to help ensure that the proper number of packages are contained inside the case.

Metal detection works very well with dry/kibble pet food and treats that do not have a product effect in the way that wet or moist pet foods do. Metal detection equipment provides reliable, cost-effective protection from even the smallest metal contaminants found in pet food production anywhere in a process. If the packaging material contains metal, X-ray inspection would be the better choice. In addition, if there are other contaminant concerns such as stone, high density plastic or glass, X-ray inspection systems will detect these contaminants as well.

Since wet or moist pet foods have a high product effect, X-ray inspection is the best technology to detect contaminants such as metal, glass, stone, and other dense foreign objects.

To help ensure pet food processors are not under or overfilling packages, checkweighers are used to verify the correct weight of each package. Accurate weight avoids giving away costly product or from receiving hefty fines from regulatory bodies for underfilling.

For pet food products in cartons, cans, bottles, or pouches, a chain checkweigher offers line speeds up to 700 packages per minute. It is appropriate for both dry and wet environments.

X-ray inspection of packaged and bulk food products is proven to be extremely safe. There is no documented evidence of adverse health effects of X-rays on equipment operators, the food products that travel through the equipment, or pets ultimately consuming those products.

A checkweigher is made up of a controller and a weigh frame. The weigh frame typically has 3 sections: infeed, the weighing section, and outfeed. The package being weighed goes through the following steps:

• A package moves from the customer’s conveyor onto the checkweigher infeed. The conveyor speed of infeed and the weigh table are the same.
• The package is weighed on the weigh cell of the weigh table.
• The package moves onto the outfeed of the checkweigher to be accepted or rejected according to the checkweigher settings.
• An accepted package moves onto the customer’s downstream conveyor.

The packages are moved along by belt (motor), chain (uses motor to pull items forward), and/or skates (slider). If the measured weight does not meet specification, the product is rejected via air blast, pusher, bopper, diverters, or drop flaps. Ideal spacing between packages allows for a zeroing operation for maximum accuracy.

Both food and non-food packages can be weighed on checkweighers. Meat, dairy, wet and dry ingredients, baked goods, confectionary products, pharmaceuticals, personal care items, and even bags of construction material like cement can be measured. Items of different forms and structures, such as those listed here, can be weighed on a checkweigher:

• Rigid (cans, cardboard packages, plastic, glass)
• Soft (plastic, paper, foil)
• Wet (dairy, hummus)
• Dry (rice, oatmeal)
• Raw (chicken, beef, fish, vegetables and fruits)

It is worth noting that loose, continuously flowing product cannot be weighed on a checkweigher.

It depends on the product being weighed and the checkweigher that is installed. Here are two examples: The Thermo Scientific Versa 8120 Checkweigher works with line speeds up to 550 rigid packages per minute. The Thermo Scientific Versa Frame 44HB Heavy Duty Weighframe is designed for rugged industrial environments with line rates up to 100 packages per minute (up to 300 fpm depending on package length).

Proper design of the in-line checkweigher can influence accuracy. These are some of the key factors: 

• Product speed
• Product weight and size
• Product transfer onto and off of the checkweigher
• Reject method and design

Conveyors must be level and aligned. Belts and chains should be inspected regularly for wear or product buildup, while gaps between conveyors should be minimized and infeed and weigh table belts or chains should be running at the same speeds. Another factor that influences weighing accuracy is the spacing between products centers to help ensure more than one product is not on the weighing table at any one time. Calibrations for all of the factors listed here should be done regularly.

The Thermo Scientific Versa Flex and Versa Flex GP Checkweigher line targets dry packaged applications such as baked goods, snack foods, prepared foods, condiments, pastas/rice/beans, baking ingredients (flour, sugar, etc.), and personal care products such as diapers, soaps and creams, as well as pharmaceuticals.

The Thermo Scientific Versa Rx and Versa RxV Pharmaceutical Checkweighers are specifically designed for pharmaceutical applications. These systems are highly accurate—within ±50mg at 3 sigma and speeds up to 550ppm. They have a clean design with a slack belt knife edge infeed transfer for unparalleled accuracy and optimal product handling. They are ideal for a variety of products, including blister packs, cartons, plastic bottles, glass bottles, pouches and small aerosols.

The Thermo Scientific Versa Teorema Can Checkweigher is designed specifically for high-rate can weighing. A feedscrew properly spaces open or closed, steel or aluminum cans at speeds up to 700 cans/minute. The equipment includes side-to-side conveyor transfer capability at the in-feed and out-feed as well as photo-eyes to provide controlled feed of cans via a can-stop.

Checkweighers can sometimes come in contact with food products that can leak or spill. The equipment has to get washed down regularly to prevent contamination so it must meet IP65 Washdown requirements. Therefore, checkweigher components are made of materials that can withstand washdown using chemicals. They are constructed of austenite steel, ANSI Type 304 SS (stainless steel), or for harsher situations, ANSI 316 stainless which is more impervious to corrosion than 304 SS.

Equipment is generally designed with minimal flat, horizontal surfaces and slots to reduce food buildup, and use stainless steel conveyor beds. IP65 enclosures provide basic waterproof protection from water, including jet sprays used during washdown.

Checkweighers do not find physical contaminants but they can be combined with food metal detectors and X-ray inspection systems that do find contaminants. Food manufacturers can find metallic and non-metallic foreign objects and eliminate “wet” product effects common with metal detectors. When combined with checkweighers, metal detectors and X-ray inspection systems offer enhanced capabilities to inspect packaged products for missing pieces or components, under and over-fills, and other quality problems.

Multiscan food metal detectors utilize a true spectrum of frequencies along with new signal processing, thus reducing the probability of an escape to near zero. The critical control point (CCP) scans up to five completely adjustable frequencies to find metal types and sizes previously undetectable. It’s like having up to five metal detectors back-to-back in a production line. It reduces the probability of an escape by many orders of magnitude.

While metal detection can be challenging even with five frequencies, Multiscan technology can be easy to use. Multiscan metal detectors utilize wizards, graphical displays, and reports to help with set-up, use, and adjusting performance.

Feedback is immediate. When running, Multiscan allows you to view all the selected frequencies in real time and pull up a report of the last 20 rejects to see what caused them.

The Multiscan metal detector automatically balances frequencies electrically. While it takes a few minutes the first time, it has a big impact on performance. To save time, the last balance data is used unless a new frequency is added. The software also runs an autobalance process continuously to remove the final errors caused by very small imbalances. There is even a balance diagnostic screen for advanced users to make sure balance is correct and there isn’t an internal problem with the metal detector.

“Product effect” occurs when a product has a conductive property which affects the magnetic field generated by the metal detector. This is typically found in high-salt, high-moisture products. And it can be a challenge to food safety.

The best way to overcome this challenge is to utilize additional frequencies. Food metal detectors that are equipped with Multiscan technology enable operators to pick a set of up to five frequencies from 50 kHz to 1000 kHz. The technology then scans through each frequency at a very rapid rate. Running five frequencies helps to get the machine close to ideal for any type of metal you might encounter. Sensitivity is optimized, as you also have the optimal frequency running for each type of metal of concern. The result is that the probability of detection goes up exponentially and escapes are eliminated. 

The best frequency is the one that catches the metal, but unfortunately, different sizes of the same metal have different magnetic and conductive reactions. And the shape, orientation, and position of the metal can change the resulting signals in a metal detector. The best metal detector technology is the one with the ability to scan multiple frequencies at once. The more, the better.

Using up to five frequencies does not mean Multiscan technology will create five times the number of false rejects. If you discover that any of the rejects were false you can quickly jump to the controls that need adjustment.

It is widely understood that ferrous metal is the easiest type of metal to detect due to the magnetic properties of iron. An electromagnetic field reacts most when a ferrous metal is in it, and the lower the frequency is, the greater the reaction.

Conversely, stainless steel, which is an alloy containing less ferrous metal, and has little or no magnetic property. To find stainless steel with a metal detector requires running a high frequency, as opposed to the lower frequencies used for ferrous materials. The high frequency field induces a current in the stainless steel, which in turn creates a new field that interacts with the original field in the metal detector to create a signal.

Every detection system has a probability of an escape. The type of metal, its shape, position, product effect, etc., all are factors in detecting a metal contaminant. Consider this hypothetical example: Assume in the past you have found that 1 out of 1 million packs (1 ppm) incurs an escape. At a pack per second, 16 hours a day, 5 days a week, that would result in an escape about every 3–4 weeks. That escape could cost thousands to millions of dollars. Multiscan technology reduces that number significantly, because it’s like having five metal detectors back-to-back running the same package at different frequencies.

Small metal foreign objects generate very small signals, and the metal detector is often operating in a factory environment with many possible noise sources that can confuse the metal detector’s electronics and software. Make sure you address any sources of interference that may compromise your testing:

• Large motors turning on and off
• Electronics boxes broadcasting wide spectrums of radiated noise
• Production equipment vibrating and causing the antenna in the metal detector to move ever so slightly
• Electrical power surging and dropping
• Temperatures swinging from freezing to boiling and back again

The size of the head is based on the dimensions of the package. Always simulate production conditions as closely as possible, including speed, temperature, and orientation of the product.

For most applications the size of the aperture should be 2 inches wider and 2 inches taller than the largest package intended to pass through the food grade metal detector.

For wet and conductive products, center the package vertically in the head, helping to ensure the same amount of distance is above and below the package. Often this means the head height will be larger than the standard sizing recommendation. This helps reduce the product signal by moving the product away from the electromagnetic coils.

‘Frozen’ is a general term. For metal detection, it’s critical that the actual product temperature and state are fully understood as results will change drastically. Products that are completely frozen to the core will often ‘learn’ as a dry product does with little to no product effect. In contrast, a partially frozen product will respond much differently passing through a metal detector and can cause excessive false rejects as production conditions vary throughout the day. Ideally, it’s best to set up the metal detector for frozen food in the production environment at the correct temperature and state.

The default sensitivity setting is 6 dB (or 50%) below the peak signals encountered during the learn process. If the product has an inconsistent signal this generally is a safe setting.  If the signal is very consistent it may be acceptable to increase sensitivity to 3 dB (or 30%) below the peak signals. Set the detect thresholds to about 1.2 to 1.5X the maximum product signal for standard metal detectors. For Multiscan food metal detectors, the equipment testing best practice is to set both in and out of phase 3dB less (1.4X) than reject signal (36 dB).

For all food grade metal detectors, eliminate as much background noise as possible. Then start with the manufacturer’s default settings. Ensure production samples are used for setup.

When metal is missed on the leading or trailing edges of a standard food grade metal detector, adjust sensitivity per the manufacturer’s recommendation and, when required, increase metal size until it is detected. 

It is widely understood that ferrous metal is the easiest metal to detect due to the magnetic properties of iron. An electromagnetic field reacts most to ferrous metal, and the lower the frequency, the greater the reaction. Conversely, stainless steel, which is an alloy containing less ferrous metal, has little or no magnetic property. Metal detectors must run at a high frequency to find stainless steel, as opposed to the lower frequencies used for ferrous materials. The high frequency field induces a current in the stainless steel, which in turn creates a new field that interacts with the original field in the metal detector to create a signal.

Small metal foreign objects generate very small signals, and the metal detector is operating in a factory that has many possible noise sources that can confuse the metal detector’s electronics and software. Make sure you address some of these sources that can interfere with your testing:

• Large motors turning on and off
• Electronics boxes broadcasting wide spectrums of radiated noise
• Production equipment vibrating and causing the antenna in the metal detector to move ever so slightly
• Electrical power surging and dropping
• Temperatures swinging from freezing to boiling and back again

Most raw foods and ingredients originate in a natural environment such as a field, orchard, or farm. As the food is harvested, foreign objects such as stones or glass can be picked up and transported into the processing plant. Additionally, objects found in manufacturing facilities, such as metal and some very hard plastics, can find their way into the processing stream as the result of machinery or process failures. These risks and associated costs have driven more demanding detection policies worldwide. Food processors are integrating X-ray detection as part of an overall food safety program to help ensure that the end product is free from unwanted contaminants before it reaches the consumer.

Food X-ray inspection systems are based on the differences in densities of the product and the contaminant. X-rays are simply high-energy light waves with a very short wavelength, invisible to the naked eye. As an X-ray penetrates a food product, it loses some of its energy. A dense area, such as a contaminant, will reduce the energy even further. As the X-ray exits the product, it reaches a sensor. The sensor then converts the energy signal into an image of the interior of the food product. Foreign matter appears as a darker shade of grey and helps identify foreign contaminants.

If you want to learn more about how food X-ray inspection systems work, download our free e-book, A Practical Guide to Metal Detection and X-ray Inspection of Foods. 

Food X-ray inspection systems do not use potentially unsafe radioactive materials to generate the X-ray images. Rather, they rely on tubes that electrically generate the X-ray beam. The beam is directed at the object it is inspecting; a digital detector on the other side of that object creates an image for analysis. One of the advantages of this system, as opposed to one using a radioactive source, is that the X-ray energy stops immediately once the tube is turned off.

With that said, food X-ray systems do generate ionizing radiation so it is important to understand what levels of exposure are considered safe, what regulations might apply, what safety devices are used to meet these regulations, and what is done during manufacturing and installation to assure complete safety in all regards. Manufacturers take measures to limit the amount of exposure, requiring mechanical shielding and curtains at the inlet and outlet of the machines to further reduce the amount of radiation leakage. It’s important that customers regularly check the curtains and replace them as they become worn.

Although food X-ray systems generate radiation during their normal use, a worker standing at the control panel of an X-ray food inspection machine will likely not receive any radiation from the machine due to shielding. In fact, these machines emit 0.1 millirems (mrems) per hour or less, and that emission is typically at the inlet or outlet where workers are not present. Multiplying 0.1 mrems per hour over the course of a 40-hour work week and a 50-week work year would imply a worker could be exposed to a total of 200 additional mrems per year in the worst-case scenario. This is significantly below the guideline for maximum exposure. The International Commission on Radiological Protection also states people can absorb 5,000 mrems annually (8X the natural dose) before radiation poses a health risk.

In the course of our daily lives we all are subject to naturally occurring background radiation. In fact, natural radiation constitutes about half of the 620 mrems of radiation an average person experiences annually, according to the United States Nuclear Regulatory Commission. As we noted in the question above, the International Commission on Radiological Protection also states that people can absorb 5,000 mrems annually (8X the natural dose) before radiation poses a health risk.

To put X-ray exposure during food production into perspective, here is the average radiation dose people receive from some common life experiences:

• Full body CT Scan = 1,000 mrem
• Natural/Cosmic rays reaching the earth’s surface = 310 mrem/year
• Trans-Atlantic Flight = 2.5 mrem
• Dental X-ray = 1.5 mrem
• Food X-ray Inspection = 0.1 mrem/hour**

**When in operation, food inspection systems can emit this maximum level of radiation per hour, typically very close to the input/output of the aperture only. Because human operators spend limited time in this location they would receive a much less (usually zero) radiation dose in an average work shift.

Download the white paper, X-ray Inspection of Food Products: The Safety Facts You Need to Know

Most X-ray inspection systems utilize one beam that is directed vertically through the package, from top to bottom. Sideshoot food X-ray inspection systems utilize horizontal X-ray beams (back to front).

An industrial food X-ray inspection system is one of the first lines of defense to identify the presence of foreign contaminants in food products before they leave the processing plant. In an X-ray image, darkness represents density. When coupled with automatic image analysis, X-ray systems can find contaminants that are dense, have sharp edges, or are a particular shape or size. These include metal, glass fragments, stones, and plastic or bone pieces.

Industrial food X-ray inspection systems are based on the density of the product and the contaminant. X-rays are simply high-energy light waves with a very short wavelength, invisible to the naked eye. As an X-ray penetrates a food product, it loses some of its energy. A dense area, such as a contaminant, will reduce the energy even further. As the X-ray exits the product, it reaches a sensor. The sensor then converts the energy signal into an image of the interior of the food product. Foreign matter appears as a darker shade of grey and helps identify foreign contaminants.  

In food X-ray systems, the X-ray beam should be oriented to pass through the smallest dimension of the package. This would be the side of tall upright containers. Most food X-ray inspections systems utilize vertical X-ray beam (top down) systems to perform X-ray contaminant detection and product inspection for flat packages like bags or boxes. Shooting through tall packages vertically means the X-ray beam must penetrate the entire height of the container, which is the thickest, most dense dimension. Sideshoot X-ray inspection systems utilize a source that is located in front of or to the rear of the machine, shooting a horizontal beam through the side of upright cans, bottles, pouches and other tall vertical packages. A large horizontal beam provides improved sensitivity and more accurate results when scanning vertically-oriented containers.

The Thermo Scientific Xpert Sideshoot X-Ray Inspection System is engineered for high-speed can, bottle, carton, and pouch lines of up to 500 packages per minute. The detector scan rate reaches up to 2800 lines/second.

Single-beam units, although effective, sometimes have ‘blind spots’ at the bottom of the container, especially when the bottom is thick and domed. Sideshoot food X-ray systems that have multiple beams positioned at different angles minimize and significantly eliminate blind spots, increasing the probability of detecting smaller contaminants in this area.

Yes, when the caps/lids are made of metal, Xpert Sideshoot systems can detect missing or cocked caps and lids. However, since caps/lids vary, software for the specific product geometry must be utilized.

Yes, though radiation-blocking curtains often cause upright containers to be knocked down or shifted. In this case, a chicane-style enclosure with a curved shape eliminates the need for curtains, because X-rays can’t go around curves — although curtains are available if preferred.

Yes, the Xpert Sideshoot system meets HACCP (Hazard Analysis Critical Control Point) requirements.

Multi-beam food X-ray systems should be used for glass-in-glass inspection because the multiple beams provide more views of the same bottle, increasing the detection of smaller glass.

Yes. Vial sizes and shapes vary and may require more than one timing device. A timing device is required to properly space the vial. In addition, the equipment footprint is very large.