The demand for poultry is growing worldwide and has already exceeded the demand for beef and pork. A large amount of the poultry is not only delivered as whole slaughtering body, but there is a worldwide trend towards prepared poultry.
This changed the consumer demand for poultry products and the trend to have products which cause a minimum of waste products. For a long time, one problem of the further processing of poultry has been de-boning which made industrial processing more difficult. In the past few decades, this problem has been solved and mechanical de-boning of poultry has become common practice in the companies. It is possible to bone manually or mechanically, however manual de-boning with 150 kg/shift is very hard work. This is why the development of modern, highly-efficient departments for further processing of poultry at any given capacity was not possible without mechanical de-boning.
What is special about poultry
De-boning can be applied for eviscerated carcasses of chicken, young chicken and ducks as well as for their separate parts such as wings, necks, back / shoulder portions. In mechanical de-boning of whole carcasses, the filet and the drumstick meat are the most important raw materials as they contain the least connective tissue and fat.
The most efficient technology that can be recommended:
- dissecting the carcass
- separation of the breast and leg meat
- mechanical de-boning of the less valuable parts such as neck, wings, back/shoulder portion from bones and meat residues.
Roast chicken consist of: 25-26% breast portion, 32-34% drumsticks, 10-12% wings and 23-25% bones. When the breast part is de-boned manually, you get around 15-18% of filet and around 20-22% of boneless meat when the leg is de-boned, in proportion to the overall carcass.
The breast and leg meat is used for the production of gourmet sausages, tinned products and semi-finished products. The less valuable meat is de-boned manually and a yield of around 60-75% of the original product can be reached.
The meat from the mechanical de-boning process is also wholesome as a food and it contains about 12% of protein and 14-30% of fat, depending on the raw material.
Under the application of a certain pressure the connections are destroyed which hold bones, muscles and fatty tissue together. In manual de-boning processes, this destruction is implemented by means of a cutting process with pressure on the knife edge and in mechanical de-boning processes by means of a system which ensures the required pressure.
Different types of press
The mechanical de-boning of the poultry is implemented with two types of systems which have distinct differences: periodically operating hydraulic presses and continuously operating spiral presses. The destructive character of the tissue is different in the different presses due to the different pressure. In the hydraulic pressing process, the mechanical de-boning process relies on the selective transition into a flowing tissue state, which consists of a non-destroyed raw material structure with subsequent flow of the liquid meat fraction through jets. They are installed on the walls of the work cylinder and play the role of a sieve which ensures the separation of hard fractions from liquid matter. The pressing process in hydraulic presses works in a "thick" layer which develops a considerable resistance of the interior transition in the flowing fraction. This is why in hydraulic presses very high pressures between 20 and 40 MPa are applied; as a result there are significant specific parameters with respect to the required metal and energy.
The process of mechanical de-boning is very different in continuous systems. In the spiral trough the material is continuously moved. In spiral pressing processes the destruction of the muscle and connective tissue works with a different action of force. Due to these different separation processes, the separation in spiral presses works at a much lower pressure. In the different countries around the world, different systems are used for the mechanical de-boning of poultry (see table).
For the mechanical de-boning of poultry normally spiral presses are used which require less specific metal in their construction compared to hydraulic systems. The energy requirements, the size and the costs of the system are much lower. The final product displays finer bone inclusions at a rougher structure.
The use of these machines leads to noticeable improvements of the product quality (structure) on a continuously high level and at precisely reproducible production parameters.
It is not only the granular, smear-free quality of the produced sinew-free, bone-free and skin-free sausage meat, but also the great reduction of time expenditure compared to high-quality, manual product separation and the standardisation which have to be emphasised. With the Baader process products with a calcium content of no more than 100 milligrams of calcium per 100 grams can be produced. A squeeze band transports the product to the perforated basket and squeezes the soft components through the orifices. The firm components remain outside the basket. An adjustable roller can determine the ratio of yield and quality. One of the most recent developments is a pneumatic stuffing unit for Baader 603, Baader 605 and Baader 607. This stuffing unit makes it possible to process the following products continuously without pre-cutting:
-whole chickens with a perforated basket orifice size of 2 to 3 mm, yield 70 - 90% (see KIN analysis)
- wings and drumsticks with a perforated basket orifice size of 2 to 3 mm, yield 80% (see KIN analysis)
- leftover meat recovery from carcasses (MDM), yield 55 - 65% with a perforated basket orifice size of 2 mm (see KIN analysis)
A new application variant of Baader is the combination of a separator and a downstream spiral separator. In this way you have two product classes and an additional yield of about 4-6%.
Recently Baader have improved the pressure system by developing a support chain which actively supports the squeeze band with rising pressure and hereby improves the entire process. The gentle technique reduces excessive loads on the machine and product throughout the entire process and it hereby ensures a much longer life cycle of the squeeze band. This also means there is a reduced spare part expenditure and therefore reduced operating costs and an expanded service life of the machine.
Source: Meat TechnologyAuthor: ast / Editor fleischnet