Controlling fat content is important for food processors who need to ensure the quality of the meat used in recipes and to comply with food legislation. Analysis is also important in making products that claim to have low fat content.
Near infrared reflection (NIR) or near infrared transmission (NIT), microwave and x-radiation have become three of the most widespread techniques used by processors to determine fat content insorted raw meat according to a paper by Wolf-Dietrich Müller and Irina Dederer, scientists at the Institute for Technology in Germany.
Fat analysis machines can either be in the form of bench instruments, which analyse small samples taken manually from the overall batch, or as devices connected to the production line.
Production line devices are more accurate and faster than the bench machines, which are dependent upon operating personnel to chose representative samples, the two stated in a paper on their testsof CFS's MasterTrack. The tests were carried out on beef, pork and poultry while the meat was being ground in an industrial grinder.
They tested meat with fat content levels that varied from a low of 0.9 per cent to a high of 80.7 per cent. Under the tests MasterTrack had an error rate of below one per cent, within the level ofaccuracy required by German law, Müller and Dederer state.
MasterTrack uses x-rays and spectral or wavelength analysis to determine fat content. Spectral analysis using the x-ray technique has the advantage of being able to detect density differencescaused by any air pockets in the meat, allowing it to compensate in its analysis, they stated.
Without the spectral analysis, the x-radiation method by itself gives high error rates because frozen meat absorbs less radiation than meat at room temperature.
They also noted that MasterTrack's spectral analysis method allows all three types of meat to be read accurately with only one calibration of the instrument. Other machines usually requirecalibration for each type of meat used in production, thus slowing down the line.
The machine is used in combination with a grinder and an optional weighing belt. The belt can be used to weigh the meat while MasterTrack is analysing it for fat content.
"This ensures that throughput fluctuations occurring through uneven loading into the grinder or the combined use of fresh and frozen meat are compensated for," they stated.
MasterTrack can also be operated as a stand-alone fat analyser, separate from the production line.
Müller and Dederer's research was published in Fleischwirtschaft magazine. The Institute for Technology is part of the Germangovernment's Research Centre for Nutrition and Food in Kulmbach. Müller is in charge of testing new processing technology at theinstitute.
The two scientists note that devices using the NIT/NIR method need to be calibrated each time a switch is made between fresh and frozen meat on the production line. The measurement of frozen meatis not possible using the microwave method.
Since July 2003, the EU restricted the definition of meat to mean the skeletal-attached muscles. Other animal parts such as fat and offal have to be labelled as such and not as "meat". Fat thatadheres to the muscles may e treated as meat, subject to the maximum limits determined by the EU's directive.
The law also requires processors to label their products with the percentages of muscle-meat, fat or offal content. The directive applies to products that contain meat as an ingredient, while meatsold without further processing is excluded. The affected products include sausages, pâté, cooked meats, prepared dishes and canned meat.