X-ray technology for routine analysis of fat in meat

10. May, 2018
By Richard Mills,
A definition of the technology as applied in food production

X-ray analysis is well known from medical applications and security scanners at the airport, but perhaps not so well known in food production.

The short wavelength of X-rays allows them to penetrate all sorts of materials. Some of the X-rays get absorbed and the rate of absorption depends on the density of the material encountered. For instance, the femur in your leg shows up because it absorbs more X-rays than the surrounding flesh and, likewise, those nail scissors that you forgot to take out of your hand baggage absorb at lot rays and will show up strongly against other items.


X-ray wavelength

The X-ray advantage
X-ray is just one of three main options for testing fat content in meat.

The classical reference analysis is the Soxhlet method. A sample of meat is weighed, the fat is extracted from the sample and weighed, and the fat is calculated by dividing the weight of the fat by the weight of the sample. 

Another option is NIR.  As discussed on our NIR technology page, Near Infrared is a much faster and more convenient alternative to the reference method. A sample is simply plucked from a production line and tested in a matter of minutes. 

X-ray is even faster, but the big difference compared to NIR is in the way it can measure entire batches of meat as they pass through the instrument on a conveyor belt, just like your bag at the security check.

This gives a complete and continuous measurement of entire batches of meat which is particularly useful given the inhomogeneous nature of meat. For example, a batch of meat trimmings will consist of some cuts that have a lot of fat and others that are leaner. Measuring everything gives an accurate assessment of the total fat content allowing effective sorting and segregation leading to better quality and improved profitability in subsequent processing.  

DEXA X-ray and how it works 
When it comes to measuring fat in meat, a form of the technology called dual energy X-ray Absorptiometry (DEXA) is particularly useful.

The simple version is that meat is passed through the analyser on a conveyor belt, exposed to X-ray rays and its absorption of those X-rays is detected and measured.  The result is displayed on a screen. The data can also be fed to a factory control system, for example, when building bins of trimmings with an automatic tray-sorting system.  More on this in the video here. 

The main elements of a DEXA X-ray system are an X-ray generator, a sensor and conversion unit which converts the X-ray energy to light and image processing technology to calculate the result.

DEXA X-ray works by measuring the absorbency of two x-ray energy spectra.

An X-ray generator projects two specific X-ray energies (a high energy and a low energy) through the meat passing through the analyser on a conveyor belt. 

The X-rays that pass through the meat are detected by a detector, consisting of a scintillator, converting x-rays to visible light, and a line of light sensitive diodes, converting light into an electrical current.

The electrical current is digitized and fed to a computer. 

Image processing algorithms use the data to map the relative ratio of energy absorbed at different points in the product.

This data map is used to determine the average fat content of the scanned material.

Foreign object detection

As well as measuring fat, X-ray can spot any foreign objects like fragments of bone or metal objects that have somehow got into the batch.  

These objects can come from production equipment in the plant or be embedded in the product. Foreign object scanning can take place early in production to protect machinery or later on the finished product/package to protect the consumer. A signal can be sent from the analyser to an automated rejection system that pushes the meat in question (a plastic tray for example) out of the production line. For more on this see this animated video of a typical X-ray installation in a meat process.
This animation demonstrates the MeatMaster II as it scans boxes of meat for determination of fat percentage and weight.
Get an overview of how to sort/build batches according to specification and other benefits such as; foreign object detection and (box ID) data storage.

Grading of cuts
With x-ray technology it is possible objectively to grade whole cuts such as pork bellies and pork hams into uniform categories, which is not achievable via the traditional visual inspection. The grading is based on fat measurement and can be combined with image recognition. 

The benefits of this technology apply for manufacturers of bacon, producers of dry ham products and other manufacturers of finished meat products based on whole meat cuts. Suppliers of raw meat cuts can also ensure that deliveries are to specification (size, length, width, thickness), fat-content and without foreign objects.


Is X-ray harmful to food or for the operators using analysis equipment? 
Exposing food to X-rays and placing X-ray equipment on the production floor in a meat plant naturally raises questions about the harmful nature of X-ray. 

Irradiated food does not become radioactive and the minimum level of radiation used when radiating food to kill bacteria, is more than a hundred thousand times higher than the level used in meat plant X-ray equipment. The meat products do not require special labelling after analysis.

The radiation level of X-ray inspection equipment used in meat plants is comparable to low level medical procedures used on humans. There are very strict rules for the design, construction, installation and test of X-ray apparatus, enforced by the local authorities. X-ray machines in meat plants, provided they are operated according to instructions, are safe to operate and are safe for the operators working in the vicinity of the machine. In this respect, the instruments used in meat plants can be compared with the baggage scanners known from every airport around the world.

The more accurate the system, the faster the return on investment in an X-ray system will be.
Naturally, the measurements need to be performed ‘in line’ at a suitable speed so as not to cause a delay in the process
See more in our video on in-line fat analysis with X-ray here:

The seven elements of a good X-ray instrument

  • Stable performance
    It is essential that fat analysis equipment is stable over time and well calibrated and that a good quality control system is maintained. This is especially so for measuring fat which is a much more sophisticated measurement than detecting foreign objects.

  • Accuracy at speed
    Measuring fat with X-ray is all about getting the right balance between lean and fat in final products such as ground beef or deliveries of trimmings. A reliable accuracy of maximum plus/minus one percent (SD) will allow you to push closer to fat targets, avoiding lean meat giveaway but without going over targets and getting returns or fines. The more accurate the system, the faster the return on investment in an X-ray system will be. Naturally, the measurements need to be performed ‘in line’ at a suitable speed so as not to cause a delay in the process See more in our video on in-line fat analysis with X-ray.


  • Compact
    X-ray analysis equipment can be quite large (around two metres wide) and the installation of any new equipment in the production line often requires that other equipment is moved around. It must be as compact as possible with options specially designed to fit into tight spaces.

  • Ability to measure all types of meat
    The great advantage with X-ray is that it can measure all sorts of meat samples presented in different ways. Any system should therefore be able to measure the meat in different forms, for example, as whole cuts, trimmings or minced meat in cartons, plastic trays or loose on the belt, chilled and/or frozen.

  • Robust IP69K approved units that are easy to clean
    An IP69K approval indicates that a unit is robust and suitable for use in the harsh conditions of a meat production plant. It must be easy to dismantle for cleaning of parts in contact with meat such as the conveyor belt. 

  • Precalibrated
    Installation and commissioning should be possible within a few days using a supplied calibration that only demands a few adjustments according to local conditions. For instance, pre-calibration for pork, beef and poultry data allows the user to work on a wide range of products.
  • True network capability for effective instrument management 
    True networking is much more than an internet connection. It should allow you to look inside the instrument to check performance and make adjustments or updates to calibrations. This is a must to allow remote management and surveillance of multiple instruments from a single location. All updates and calibrations can be performed centrally for improved instrument performance and convenience. Not only does this save you time, but it has also been shown to significantly reduce costs. 

FOSS products using X-ray

MeatMaster II

MeatMaster™ II gives continuous “real time” measurements of fat content and weight of all the meat passing through the instrument on its built-in conveyor. It can scan up to 38 tons per hour and also performs foreign object detection.


MeatMaster II C 

At just 1.58 metres in length, the MeatMaster II C is nearly a metre shorter than the standard MeatMaster II and is designed to fit into production areas where space is tight. It can measure meat in boxes and trays, including blocks of frozen meat.


MeatMaster II AG 

The MeatMaster II AG is another dedicated version which is aimed at producers who need an accurate measurement of the fat content in ground meat as it is transported from the grinder to the mixer.



Read about other technologies

When Danish Crown installed the MeatMaster™ II X-ray analyser they were able to optimise and increase the value of their beef trimmings.
See how the system is integrated and used to build batches for minced meat production.