Are there metals in food? Use magnets as a metal detector

We have advised on several projects about metal in foods, and here we share our experiences from the various projects. You will find both info on using magnets as a metal detector and info on how to easily remove metals from food.

This is one of the longer posts, but it is in return packed with magnet knowledge, and there is also a video further down that shows how we spot metal in food / candy.

If you work with metal in foods, we must point out that you cannot read snippets of the following to quickly conclude anything - it's important that you read the entire post, as we along the way come up with both challenges and conclusions. And the sub-conclusions cannot stand alone.

An important place to start is with the following question:

Are there metals in food?

The food industry is subject to strict rules regarding the tracking of metals in food. the food administration monitors the producers, but in addition, the producers also do a lot to avoid the occurrence of metal in food. In this post, therefore, we will both discuss how to track metal in food and candy, but also the different processes foods must go through to track metal. Thus, you can become wiser both as a consumer on how the process is, but also as a food producer on what you can do with magnets to optimize the process of spotting where a piece of metal originates from, so you can quickly fix the machine that needs to be checked for wear.

But just to clear any doubt for consumers: you should as a starting point not be nervous about metals in food. And you can read much more about here why.

Here you can find some of the best magnets, searching for metals in food - that we have tested (and you can find more details about metal in different types of food below the products):

Metal in breakfast

Back in 2018, we were contacted by a major Danish newspaper who wanted to write an article about metal in breakfast. They had planned for the very big thing, and they had bought several packages of cornflakes etc., which we had to test for traces of metal or metal residues.

They were quite convinced that there was plenty of metal in the Danish breakfast.

So we went with some of our biggest magnets and all food was thoroughly tested and chopped up to make sure we didn't overlook even the tiniest piece of metal.

But we didn't find anything. There was no reaction and no metal shavings to be found afterwards. That is we could not spot the slightest reaction or find any kind of metal parts.

It was not the result the journalists had hoped for. Unfortunately! Otherwise, we think that the news about "no metal in Danish breakfast" was at least as good as having found metal in the food, because it was good news after all. But that kind of good news doesn't sell as many papers as a scandal story... So the paper dropped the story about breakfast being magnetic and full of metal waste altogether.

Metal in grains

In all production with machines, there may be metal residues, because there is wear and tear on the machines over the years, which is unavoidable. The same goes for grains. We were therefore contacted about rebuilding a chute that was supposed to transport the grain over magnets, so possibly metal shavings could be sorted out (ie captured by the magnets).

The solution was built up with a chute in 2 parts: first a wide part, which was made in the shape of a funnel (like a Y), where it was easy to pour the grain through in large quantities without spillage. Then a space where we placed 3 large 60x30x15 mm. power magnets. And finally the last part of the chute, which acted as a kind of landing strip for the grain after it had jumped over the magnets, where it was collected in a vat before final processing.

Subsequent tests in a metal detector showed that the magnets worked, because there was nothing to trace, and the construction therefore worked exactly as intended. But that's not enough: because magnets only begin to lose their magnetism measurably after approx. 80 years and noticeably after approx. 100 years, then it is a simple construction that works without electricity, and which only needs to be checked during a simple inspection to keep an eye on possible metal. Completely different from large machines that depend on a lot of factors that have to interact along the way and are continuously monitored by a technical employee. Here, magnets are otherwise simple and "cooperative" - and their function probably outlasts all other parts in the construction by many years.

Unfortunately, we cannot show pictures of the slide. However, if you need help building a similar model, we are happy to send you drawings for a similar solution.

Metal in chocolate and sweets

The last task requires a little more explanation, because the magnets can easily make the metal "react", but it is not as simple as with the cereal and the breakfast cereals.

The task itself consisted of sorting out pieces of candy from production that had gotten metal shavings in them during production. The company's problem was (as in the case with grain) that wear and metal fatigue can occur in the machinery. This can result in metal shavings getting into the products during production.

Of course we made a video - it is in Danish but we hope that you can easily see the context in the video:

We tested with these magnets:

Initial test

To find out what worked, we started by taking the Ø75 hook magnet: it's easy to hold because you can put a finger through the hook and have full control of the hook magnet in your hand.

Next, we had to plant a piece of metal in a few pieces of candy and chocolate to see how it reacted before we could test on larger quantities. We did this by breaking a piece of chocolate over and gathering it around a metal splinter and by cutting a small hole in a piece of candy where we could put a small piece of metal.

The magnets have a large magnetic field and can make magnetic metal react easily at a distance of up to 10 cm. (the closer, the greater the reaction - but it starts dancing at approx. 10 cm distance). And it makes no difference to put plastic or a wooden tray in between - the magnetic field goes through everything. That is we could easily run the test by putting the candy and chocolate on a tray with the magnet under the tray to do the test.

Challenges along the way

The first challenge was to create a setup where larger quantities can be driven through. It will not be a good solution if you have to empty a whole package of small chocolate lentils and go through each and every lens from the package. This should preferably be done by being able to pour a whole bag into a box or onto a tray, where you can, within max. 1 minute can spot the part that caused the metal detector to sort the bag out in production.

So, while the metal detector can spot the few bags of waste that need to be discarded, fault finding and the analysis of the products can subsequently narrow down and specify in which part of the overall production the problem with metal shavings occurs. But even though magnets and metal are a match made in heaven, it was not enough to get the rum ball and the chocolate nuts with magnetic shavings to roll easily against the magnet. We could easily tell which rum ball contained a metal chip (it vibrated a bit near the magnet, but we couldn't get it to roll and stick to the magnet, much to the customer's dismay (and disappointment).

So the conclusion, unfortunately, was that although big, strong magnets are wonderful and clever for a great many things, they are not a magic wand that can magically do everything; eg. to make a chocolate nut or rum ball roll.

But we didn't give up…

Why the magnets did not work as desired

The conclusion cannot stand entirely alone, because we would like to explain "why":

Let's say the candy weighs 10 grams and has a diameter of 2 cm. The metal splinter weighs maybe 0.01 gram and has a size of 2 mm. Even if we use our strongest magnet, the small metal splinter must pull a load 100 times heavier than itself, while the metal splinter is magnetic enough, but it is not a magnet in itself. A magnet with a strength of 130 kg. can make the metal shard dance, but it won't make the rum ball roll. And the same result is achieved with a setup with 4 pcs. 60x30x15 mm. magnets, which have a total strength of over 220 kg.: the metal splinter is attracted to the strong magnetic field, but it is only the splinter that "dances" inside the space ball.

For the sake of comparison: imagine towing a caravan behind a car. A little more figuratively: a nice new caravan with a weight of 1100 kg, pulled behind a big nice BMW X7 with 335 horsepower. It works fine, as the size ratio and horsepower are balanced against each other. Then you remove the caravan from the hook and attach it instead with a suction cup and a jump rope from a toy store. It is not difficult to conclude that you will not get far with this set-up, even if both car and caravan are top notch.

In our case, you can say that the magnet is strong enough, and the piece of metal is perfectly magnetic, but it simply cannot pull enough to lift a weight that is 100 times greater than its own weight.

Magnets can do an incredible amount, but unfortunately they can't do everything. So therefore a little modification was needed for e.g. to cut the larger candy into smaller pieces... which wasn't a problem because it had to be examined anyway to find out what layer the metal was in.

And as I said, we didn't quit the project

As with so many projects, you just have to be persistent. Watch our video above and how we succeeded with the project.

PS! The type of candy and certain ingredients have been changed to protect the identity of the companies.

How is metal detected in food?

The fact that we could not get the easy reaction with magnets that we had hoped for from the start does not mean that you as a consumer should be nervous about metal in food and sweets. For all food producers are subject to strict requirements regarding food safety, including metal detection. And this means that possibly metal parts are spotted by their metal detectors. But when a package or bag is rejected due to a result from the detector, there is an important task in finding out these things:

Which metal parts are involved
Where in production do they come from
How is the machine then secured to avoid more metal in the food

So you don't have to be nervous as a consumer about putting your teeth into a steak or a piece of chocolate with metal. It HAS been sorted out in the large metal detector setup.

Can you conclude anything?

This article is only about being able to spot the metal parts and subsequently find out where in production the metal originates, because in food production there are several machines and steps along the way where the metal can originate. In candy production, it can be a piece of candy that consists of e.g. licorice and wine gum or foam and chocolate. And then it is important to find exactly the piece of candy with metal in it and see which part the metal is in. Because if you cannot see where in the process it may have happened, then many machines may need to be inspected. And it is a very expensive process. Therefore, magnets can be a very good part of the subsequent analysis of metal in food products. But as you can read above, it is not that simple, as it requires that you can actually get the small metal part to move so much that you can easily spot the piece of candy etc. where the metal has got stuck. And it requires a larger setup with very strong magnets, as you can see in the video.

So the conclusion is that it can be done, but magnets are not magic, so the project needs a little help along the way with small modifications.