Food Processing Sanitation Experts

Should Food Processors Use Metal Detection or X-Ray Inspection?

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Editor’s note: This summary article was extracted from an article titled “What food processers should know: metal detection vs. X-ray inspection,” by Bob Ries, Lead Product Manager, Metal Detection and X-Ray Inspection of Thermo Fisher Scientific.

As a food processor your major area of concern is safety. With the new Food Safety Modernization Act (FSMA) the priority for safety has increased even more. With this new and revised FSMA implemented there will be a huge cost if processors do not comply with the safety regulations set forth. With that being said processors are now depending on the latest methods and equipment to help keep food safe.

One thing that happens frequently when dealing with the food processing industry is foreign object contamination. You may be thinking what does that even mean? Let me explain it to you. Most food is grown naturally in a field, farm, etc. When the food is harvested foreign objects (such as stones or glass) very well could end up being transported into the processing plant. Once in the processing plant more items such as plastics or metals can also end in the processing routine. Lastly, fragments such as bones, shells, etc. could end up in the final product.
So now that you know some of the issues that the food processing industry faces you must now choose whether or not you want to do metal detection or x ray inspection in your plant. So know I am going to lay forth the attributes of both of these types of machines.

Metal Detection and X-ray inspection has been known to be the first line of defense in the identification of contamination in food products. So at this point food quality professionals must decide which one they want to go with. When making this decision three criteria’s come into play which are: the optimum detection point, overall capability, and the overall cost and benefit.

Detection technology has been around in the food processing industry for numerous years now. However, due to the constant engineering and software developments, there has been an increase in confusion regarding which machines to buy and why.

So now I am going to run you through some of the basics regarding these machines. In security applications metal detectors use frequency signals to detect moving metals. X-ray systems on the other hand produce dense images that is looked at for anything that looks out of sorts.

When working with food these are more complex than that. The amount of items and how quickly they need to be detected causes this process to be much more difficult within the food processing industry. It is not necessarily the challenge to find contamination, but rather to ignore the product, packaging, or environment. False detections can be costly and cause unnecessary frustrations.

Metal detection and X-ray systems must be sensitive, easy to use, fully automatic, fast, very strong and durable, reliable, and cost efficient. This is a difficult task for a machine that must run for years, dealing with all types of working conditions, and seeing millions upon millions of products.

I mentioned foreign object contamination earlier in this article. Foreign object detection is determined by three ways: detectable contaminant types, minimum contaminant size, and the probability of detection. Sometimes contamination can be missed, or you find foreign objects you thought were not possible. The best way to help resolve this is prior to leaving test many samples with different contaminants. This will help you be able to interpret how these two react to one another.

To reduce contamination depends on the system design and capabilities, and the product effect. Normally the larger the contaminant, the higher probability of detection.

So at this point you now want to select the detection point. For the most part companies use HACCP methods to ensure their food safety. The first segment the HA (Hazard Analysis) tells us which contaminants are most likely to occur. The next step is being able to determine the CCP (Critical Control Point) or the best detection point. CCPs can occur at any point during the process.

Finding the perfect detection point can play a factor in which machine should be used. Metal detectors can be placed almost anywhere, but you have to choose one depending on the size of the products that are going to be entering through it.

X ray systems depend on product size as well. However, they do have a greater sensitivity with large products than metal detectors. X ray systems are limited by speed due to the basic detector sensor scanning
rate. Due to this x ray machines are typically found at the end of the line. They cannot be used in gravity flow applications due to the fact of X ray machines needing a constant known speed in order to obtain an image. In these cases it would be wise to use a metal detector.

The next step is the decision making process. Before you decide on which machine to use you must ask what contaminants do you want to use and where do they come from? After you have been given all of the factors that affect the performance the best thing to do is to run a test in order to help select which one you would like to use. Do everything you can to try to make it fail, and try receiving 100% detectability without any flaws. You want to ensure that you have enough detection margin. This will allow the system to run trouble free for hours.

Now I am going to touch upon X-ray inspection guidelines. As we all know X-ray systems create a grayscale image matching to density. In order to detect contamination the contaminant must have a significant contrast compared to the product. The only way to truly find out what can and cannot be detected is for an application specialist to run a test.

The next thing you need to keep in mind when deciding on which machine to go with, is the packaging material trends. Many brand owners have switched their focus on using packaging material that is cost efficient, and increases the amount of time the product can remain on the shelf. This has made many industry leaders to switch to metalized films or foil based structures. This material helps with preserving the product while also providing better oxygen, moisture, and protection from Ultra Violet lights.

The one problem with this is that these are not compatible with metal detectors. On the contrary X-ray systems can see right through this type of packaging, which in turns allows them to be able to detect even a very miniscule amount of contamination.

The next issue you will need to be aware of is the ability for the machine to detect missing products. Once again, X-ray detection machines take this category. The reason for this is because X-ray machines have the ability to look inside of a package. This allows them to not only detect when contamination is present, but also see if something is missing. Metal Detectable machines cannot do this at all.

Next, you will need to weigh your equipment cost versus your failure cost. Too many small accidents in your company can lead to millions of dollars being spent, and complete and utter destruction of your business. As a business owner/manager you must first ask yourself “How much am I truly willing to risk? You want to put this up against the total cost for the X-ray or metal detectable machines. These costs would include, installation, training, maintenance, repairs, and cost of downtime.

Metal detectable systems tend to be cheaper than X-rays systems. They also tend to have a 2-5 times longer life expectancy. If your major area of concern is metal contamination in small, dry products, then choose metal detectable systems. If you would like to find glass, rock, bone, plastic, or have metallic packaging materials, then X-ray systems are the path that you would want to go down.

So now that you have a brief background on both metal detectable and X-ray systems you must now decide on which one will best suit your interest. This can be a long and difficult process. Before choosing which one you would like, you first should look up companies that sell both of these or one or the other. After researching you should then choose a producer of these systems that have a long and proven track recorder.

You do not want to buy one just because it is the cheapest or what not. By researching these companies you be confident in the decision that you make. Lastly, make sure that your staff knows and completely understands the machines and policies. You should have a training seminar where employees learn how to use them. Also, you should have meetings to go over the safety rules and regulations. These should occur every few months, just to ensure that people know the policies, and to inform anyone if new ones have been added. After reading this paper I hope that your decision on what machine to use can be a whole lot easier, and the right one be made.

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