Accurate derinding of pork loins with robot
The robot is not yet finished, but is a long way towards completion. It was realised from the beginning that no two loins are alike; shape and fat thickness therefore vary from loin to loin. In order to enable the robot to cut accurately, it must be able to produce 3D images of each pork loin. When the robot has been completed, the image technology in it will be able to create a virtual cutting curve, which can be followed by an advanced knife system. This ensures that the slaughterhouses can produce more uniform and high quality loins.
Higher quality, better price per kilogram
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| Figur 1: 3D-figure of a pork loin before derinding. |
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| Figur 2: 3D-figure of the rind after defatting. |
Today the slaughterhouses use a less advanced derinding machine to remove the back fat from pork loins. The machine has only limited adjustment possibilities for removing a thin or a thick layer of back fat, but it cannot take in account the varying shapes and fat thicknesses of the loins. As a result the loins are not always defatted in the optimum manner. In some cases too little fat is removed, and in others the knife removes some of the costly lean meat.
Both the lean loins and the fat layers are valuable raw materials for fresh pork and sausage production. There is therefore good economical sense in using an advanced derinding machine, which can remove the back fat in one piece.
- If the fat layer is cut off in one piece, it can be sold at a high price e.g. for production of Russian salami sausages. If the fat is cut off in bits, it can only be sold at a quarter of the price, says Per Black, Project Manager at the Danish Meat Research Institute.
It is therefore sensible to replace the old machines with advanced robots that can adjust themselves according to the shape of each loin and cut with millimetre precision, although the outline between lean meat and fat varies.
The knife must follow the outline of the loin
There has always been a sale for defatted loins – particularly to Japan and Great Britain. Now the slaughterhouses can look forward to a new robot that can be adjusted to produce precisely what the customers wish to purchase. The new robot can be adjusted to leave a uniform thin layer of fat – also in cases where the outline of the loin is extremely uneven.
It has for a long time been a wish to improve the process, but only recently has the image technology become sufficiently advanced for the task. The computing power has e.g. become fast enough to form 3D images. This process must be extremely quick, as the robot has only seven seconds for each loin. The sensor technology has also reached a level, where it can supply good data for the images.
- We use our knowledge about CT-technology and particularly our experience with CT-modelling of carcass cuts. We know from the computer models how a knife must move, and how quickly it must adjust to the shape of the loins. Even when the loin with the back fat layer has a smooth surface, the dividing line between lean meat and fat is uneven. A 3D image of a pork loin where the back fat has been cut off virtually, shows that the ‘landscape’ varies considerably in height, explains Per Black.
The challenge is to make the robot cut along the outline of the lean meat of the loin, so that all the meat is left on the loin and not on the fat layer. Technically the sensors measure at selected positions on a loin when it passes on a conveyor belt. The measurements are combined with 3D models of the loins, and the 3D model then controls the very advanced knives that precisely adjust the cutting to the shape of each loin and the variation in fat depth. When, for example, the sensors indicate that the lean meat of the loin has an upward peak 10 cm later, the knife blade must adjust to this.
For further information contact Per Black, pbl@danishmeat.dk
