Ready meals are a fast-growing category. But they’re not straightforward to inspect. Here, we reveal the technologies ready to meet the challenge of ready meal inspection.
Ready meals have come a long way in the past few decades. In the words of CSIRO Professor Martin Cole: “Ready meals are not 1970s TV dinners, but highly nutritious packages designed by chefs.”
Cole, director of CSIRO Flagship of Food, Nutrition and Bioproducts, told the 2015 Future of Food conference that ready meals are taking off globally. “Everyone is time poor and yet everyone wants really good quality food.”
With the rise of ready meals in Australian households, the category’s value grew 8% in 2015 on top of 10% the year before. According to IBISWorld, the category’s revenue now sits at $900 million per annum.
The question is: how do ready-meal processors keep their customers safe and satisfied with fit-for-purpose products? What is the best technology for ready meal inspection?
Inspecting ready meals can be complicated
The challenge for manufacturers is that they need to check each ready meal has all its components; however, ready meals have multiple elements. While a manufacturer might think each is the same — for example, it has potatoes, carrots, peas, meat and gravy — to a machine, every meal is different. The amount of meat varies slightly, the shape of the potato is different, and the position of the peas in one container isn’t the same as the next. Therefore, it’s difficult for a machine to look at ready meals and make a call that something is wrong or missing.
To check the presence of each component, they need to be distinctly separated. Some ready meals are presented in this format, with trays of segmented elements, like an in-flight meal. The segmentation means it’s possible to check each element is there with a vision inspection system or potentially an X-ray inspection solution. But there are still a few challenges.
For example, one common inspection method for ready meals is checking weight. But, while a checkweigher will make sure the total weight is correct, it won’t tell you if the individual components are present and correct. The entire tray could be filled with peas and still be the correct weight, but the checkweigher cannot tell you that the meat and potatoes are missing.
The bottom line is it’s important to have a tailored system that allows you to keep your product quality high and your consumers, and brand, safe.
Let’s take a look at the inspection technologies ready to meet the challenge:
A checkweighing system will tell you if the total pack weight is right. Any over or under-weight packs will be immediately pushed off the line for rework. Because a checkweigher helps you detect issues with product overfill or underfill, you can use the data to correct problems on the line and create a lean business (read how to calculate the ROI of a checkweigher in this article).
Checking for contaminants
A metal detector or X-ray will make sure a knifepoint, bolt or other piece of metal hasn’t fallen in the ready-meal pack. Magnets can also be used to make sure there are no fine metal pieces in a pack, but they are not the most effective solution for a ready-meal application for several reasons: magnets aren’t effective on stainless steel (which is what most food processing machinery is made from) and they only pick up ferrous metal (plain steel). Also, if there’s a little fragment of steel in a piece of meat, the meat is too dense for the metal to move through (to get to the magnet) and too heavy for the whole piece of meat to stick to the magnet.
Checking for product elements
X-ray can be used to check that various elements are there or are missing. Manufacturers of prepared salads, for instance, can use a X-ray to check the oxygen-absorption sachet has been included or the presence of a knife and fork, sauce, or other components. If a knife and fork are detected, the pack is passed as “okay”. If either is missing, then the pack is rejected.
Vision systems can also perform this check in a tray, but they need to perform the inspection before the pack is sealed, whereas the X-ray can do it after sealing and in various different packaging formats such as salad bags.
Checking packaging and labelling
Vision systems can be used to inspect the product and the packaging to make sure the right labels are used and the packaging is sealed correctly. Labelling is a very real issue for manufacturers and inspecting can help avoid expensive recalls where the label on a pack does not match what’s inside.
Let’s look first at product inspection.
A sample product (say, potato salad) is made and checked by quality control. If it passes, the product is used as a reference sample to “teach” the system what to expect. After the system is taught “this is potato salad”, everything else running through that matches the reference sample is passed. Anything that does not match is rejected. The only risk is that if there is too much variation or range in a good product, the system may not be very effective.
Many manufacturers go an extra step and create a library of items to choose from when they run the line. This has the added advantage of being less reliant on the operator because there is less need to “learn” the product at the start of production. Rather, the vision system refers to the library for the reference sample, then makes the pass or reject decision based on a comparison of the product with the sample from the library. This gives a higher level of control and reliability.
For packaging inspection, a common method is for the vision system to verify a label is present on the top of the pack and a barcode is present on the bottom, and whether that label and barcode match “potato salad”. If everything matches, the product is ready for sale. If not, it is rejected. (Here are 9 ways a label inspection system can ensure zero-defect labels.)
A vision system can also check the pack is properly sealed.
Remember the golden rule for inspection
The rule is simple: products must be checked one at a time. Ready meals are predominantly packed in trays and the tray machines often feed out several at a time. Many manufacturers then allow these to travel in rows of multiples across a conveyor belt before feeding through a metal detector or X-ray.
While an X-ray can still inspect multiple products at the same time, it’s a definite no-no for a metal detector since it can’t differentiate between the units and will reject all if even one has the contaminant. The solution is to always run the products through inspection in single file.
Choose a customised solution
With the ready-meals market booming, equipment providers are increasingly devising new ways to perform inspections effectively across various applications. The key is to talk to a reputable supplier about customising a solution for your unique requirements.
Matthews Australasia can help create a tailored inspection system for your business that will allow you to keep your products fit for purpose and keep your consumers, and your brand, safe.
Check out Matthews’ vast resource library. It has a host of detailed information that’s all free to download! There are whitepapers, presentations we’ve done to industry bodies, infographics for manufacturing, case studies, articles from our thought leaders, vids showing solutions in action and more!
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