More and more processors are opting for larger birds to help drive down costs, but some are finding their plants are unable to process these high yield birds while maintaining high line speeds.

The first steps in slaughtering are usually not a problem. At a given line speed, most stunners, feather pluckers and evisceration machines can deal with a wide variety of bird weights, but not the cooling.

Most water or air chillers have been designed to accommodate with the line speed for cooling birds only up to a certain weight. But as soon birds become heavier and the limits of these coolers have been passed, the carcasses will not be cooled sufficiently, particularly not the inner breast and leg temperature as required by the food safety inspection.

combi-chillermain.jpgSeveral processors have experienced this issue and were forced to expand their cooling facility, which often means investments of several million euros. However, one Dutch company has come up with a cost effect means of chilling birds.

“We have saved one company in the Netherlands a couple of million of euros by installing our combined air-water chiller,” says Wim van Stuyvenberg of TopKip. Processor GPS in Nunspeet, the Netherlands used to kill birds up to 2kg, but when the birds became heavier, it could not cool them down to the right carcass temperature. They either experienced a too high inner temperature or a too cold (frozen) outer temperature or both.

For the time being the only choice was to slow down the line speed, which increased the cost of production. On the longer term this was not a realistic option. Extending the cooling line seemed to be the only solution, but would require several millions in investment, he explains.

After investigating TopKip’s new combi in-line chiller, GPS decided to give it a try and installed a system in one of their two lines. Soon after the first results became available they concluded that the system not only brought them savings in investment, but also in energy and improvements in product quality.

Martin Dirkse of GPS says from the start they believed in the principle of the combination of both water and air cooling. It took them, without any factory down time, a minimum of time to install the installation in the existing facility and saved them the time consuming process of getting planning permission to build an extended air cooling facility next to the plant. Following its success, GPS converted its second line.

As the inventor of the system, Wim van Stuyvenberg recognised the advantages and disadvantages of both water and air cooling systems. He has seen many processors lowering the cooling temperature and or line speed in the chiller to decrease the carcass temperature quickly.

Many believe that a little bit of ice on the carcass will not cause any harm and may speed up the cooling process. However, the opposite is true, warns Mr Van Stuyvenberg.

He especially refers to the fruit growers’ practice of protecting their fruit against frosts during spring by spraying fruit trees with water. The frost creates an ice cover which in turn protects the fruits from frost damage. But this is not what you want to see in the chiller.

He, therefore, developed a four step process by which carcasses leaving the evisceration line enter a rinsing tank, followed by a drip line to enter the pre-chilling tank containing water at 4C degrees. Thereafter, they continue their way on a drip line, a third pre-chill tank, a drip line and a fourth chill tank with water at less than 2C degrees. The carcasses continue their ride to either an air chiller or an in-line water chiller to cool down to the desired temperature.

No water uptake

The combination of water and air chilling proves to do an excellent job, says Mr Dirkse. “It brings the carcass temperature down to the desired level in less than half-an-hour where in the past it took at least two hours. We gain the most during the first four minutes when the carcass is dragged through the combi chiller.

“The carcass temperature drops then easily from 39 to 29C degrees or less, and after about half an hour in the air chiller we measure a breast meat temperature of 7-9C degrees and an inner temperature of the thigh 3C degrees. We reach this low level while the temperature in the air chiller does not go below zero, and thus never looses capacity resulting from frozen nozzels.”

Besides considerable savings in time and energy consumption, GPS sees major improvements in product characteristics. The end product is very clean and attractive, while there is no loss in yield and shelf life. “Cell counts, where it concerns salmonella and campylobacter were already low, but have definitely not increased. When comparing today’s count lists we see improvements there as well,” says Mr Dirkse.

“The only worry we had was the water uptake by the carcasses since the system alternately combines water and air chilling. EU regulations are very strict, however, the system allowed us to remain within the limits. Actually, we did not see any increase in water up take at all.”

Traditionally the poultry industry is using water chillers. They have been known for years to be very efficient in cooling chicken carcasses, but they are also known for increasing the water uptake and possible contaminations. Since all carcasses end up loose in one big chiller tank there is no way to put a 100% tracing and tracking system in place. These issues caused EU authorities to ban water chillers and only accept air chillers.

Confronted with the rules Wim van Stuyvenberg is proud to reveal that based on field experiences the Dutch and European control bodies have certified the system as being an air cooling system. This allows users to sell their products as being “Air Chilled.”