Refined and processed food products are part of most shopping lists these days, and they are increasing in quality as consumers become ever more aware of the processes and ingredients that go into their manufacture.
As such, manufacturers are under growing scrutiny both for what materials they use in their products and how they handle them during production to uphold the highest levels of food safety and help consumers lead healthier lifestyles.
At the same time, manufacturers are under pressure to produce more for less, streamlining operating costs to protect profit margins and remain competitive in a globalised market place.
How Can X-ray Technology Help?
An x-ray system is essentially a scanning device. When a product passes through the x-ray system, the internal sensors capture a grey-scale image of the product. The software within the x-ray system analyses the image and compares it to a predetermined acceptance standard.
On the basis of the comparison, it accepts or rejects the image. In the case of a rejection, the software sends a signal to an automatic reject system/ valve which removes the product from the production line.
Traditionally, x-ray machines are installed at the end of the production line to inspect finished, packaged products for contamination before they leave the factory. This allows producers to comply with the food safety legislation in effect in their respective markets, while also enabling them to meet consumer and retailer demands for optimum food quality.
However, there are many benefits to inspecting products earlier in the production process at the pumping stage as the product in question is more homogenous in texture and density, making foreign bodies easier to detect.
This also means that contaminated products are removed from the production line before further value is added through processing and packaging, reducing manufacturing costs and cutting waste.
Also, catching contaminants early is not just more efficient in terms of reduced product waste and costs, it also helps prevent damage to processing equipment caused by big contaminants, which could in turn introduce more contaminants. Additionally, when installed early in the production process it can also serve as a check on suppliers’ quality control.
Challenges In Using X-ray Technology
There are a host of factors that need to be taken into account to optimise foreign body detection rates; one factor in particular is the density of the product.
To be detectable to x- ray inspection, a contaminant has to be denser than the product in which it is embedded. That means it will absorb more x-rays than the surrounding product, and show up on the greyscale image as an area that is darker than its surroundings. In other words, any contaminant with a density similar to, or less than, that of the product in which it is embedded is incapable of being detected by x-ray inspection.
As the product thickness in the path of the x-ray beam increases, its overall level of absorption increases as well. That makes detection more difficult. A contaminant in a shallow layer of product flowing through a pipe is easier to detect than a contaminant hidden inside a finished sealed pack.
Manufacturers also have to consider product homogeneity i.e. the texture and consistency of the food to be inspected. A product with differing density, such as a sauce with chunks of vegetables or minced meat, can present a more complex and varied greyscale image than a homogenous product such as smooth fruit purée.
Products with varying densities can make it more challenging to detect contaminants without the use of specialist software developed specifically for the inspection of pumped products.
In addition to these issues of detection precision, manufacturers have to consider the impact on line productivity of their chosen product inspection machine. Whatever solution they choose must not only be suitable for the product application in question; it must also be capable of accurate inspection even at high flow rates.
At the same time, it must also support rigorous cleaning regimes, product changeovers, and regular testing procedures with minimal downtime to maximise efficiency for operatives and the business.
Customising X-ray Technology For Pumped Food Products
To be fully effective, x-ray inspection should be part of a company-wide approach to product safety and part of a product inspection programme.
Identifying the critical control points (CCPs) helps to choose the best location to apply x-ray inspection on a production line. A CCP is a step or process that is essential to product safety. It is the point at which control must be applied to reduce the risk of contamination to acceptable levels.
Connecting x-ray inspection equipment to an existing piped production line is not complicated. Standard fittings can be used to attach the pipe through which the pumped products pass to the manifold of the x-ray machine.
The manifold typically tapers the round production-line pipe to an inspection window with an equivalent throughput volume. The rectangular section is where the x-ray beam scans the flowing product.
The depth of product at this point is typically between 35 mm to 50 mm. When the software detects a contaminant, it diverts the product from the pipe via a reject diverter valve.
Advancements in x-ray technologies have made detection of contaminants even more sophisticated. These advancements include single vertical beam x-ray systems that boast a completely new set of software algorithms to offer optimum detection capabilities for contaminants such as calcified bone, glass shards and metal filings. Detection sensitivity has also improved; pumped foods can be inspected at a flow rate of up to 14 tonnes per hour in some systems.
Machine designs now improve time efficiency as well. In one such system for example, the generator and detector sit on a moveable carriage that allows it to be rolled backwards to calibrate for a quick product changeover without the need to disconnect and reconnect pipework.
Together with the automatic calibration function, the inspection system can be set up in less than 20 seconds without the need for operatives to intervene.
To maximise production uptime and enhance productivity, manufacturers should look for x-ray technologies which have an automatic testing facility option—where a mechanism within the pipe moves a small contaminant sample into the path of the x-ray beam.
This eliminates the need to manually insert a test piece into the pipework, thereby simplifying testing procedures and reducing downtime.
To conclude, x-ray inspection is a versatile technology that is suitable for the inspection of a wide range of pumped food products on CCPs on a food processing line. It helps maintain product safety and brand reputations, and can protect valuable equipment from damage.