Marel: How to maximize chilling efficiency
The main function of an air chilling installation is of course to chill birds as quickly as possible from approximately 40°C [104°F] to the required temperature without freezing any part of the bird. Freezing would compromise both shelf life and presentation. To do this, Marel puts the product center stage, creating a suitable microclimate around it. The aim is most definitely not to cool the room in which the chilling tunnel is installed.
As you will be looking for a guarantee as regards the chilling performance of the system, it is important to be precise about where the temperature is measured. Marel has opted for core temperature, the warmest spot in the breast muscle. Some suppliers guarantee an “average” temperature, which is altogether different, as it includes surfaces, which cool down much more quickly. The laws of physics will determine how long it takes to chill products to the temperature required with heavier products needing more time than lighter ones.
Local legislation plays its role too, as it will influence the chilling method chosen. In the European Union, for example, if a product is to be sold fresh, it must be chilled using air. Products which are immersion chilled in water, however, cannot be sold fresh.
If no countermeasures are taken, up to 3% yield can be lost when chilling with air. This because dry skin is hydrophobic, meaning that it doesn’t like water. Marel overcomes this phenomenon by spraying a thin film of moisture onto interior and exterior surfaces during chilling, making these surfaces hydrophilic (attract water). This film should remain intact for most of the process with any water evaporating from the film rather than the product itself. This reduces yield loss typically to half a percent. Shelf-life considerations, however, dictate that products coming out of the chilling installation be as dry as possible. Bacteria thrive in water and live only on the skin, the underlying meat being sterile. Spraying should therefore stop in good time.
Marel treats your inquiry for a chilling system on its own merits. Of course, you will have your own priorities, which could include color, presentation and tenderness. If you cut up and debone, you will not want any deboned breast meat to be tough. The ability to offer full product-by-product traceability will often be a key demand, particularly if you are selling to a major supermarket or convenience food chain. Marel chilling installations are fully in-line and will allow this.
The different characteristics of Marel chilling installations allow them to be configured wholly in line with the requirements of your particular market.
Marel offers four types of chilling installation. These are the DownFlow Plus system, the Shock/Maturation Chilling system (a DownFlow Plus chilling installation preceded by an immersion-chill stage), In-line immersion chilling and the InfraChill system.
The DownFlow Plus System is at the heart of Marel’s chilling installations. DownFlow Plus is a multi-tiered system on the top of which evaporators are installed. These evaporators blow cooling air obliquely onto the tiers below, which are offset to prevent products hanging on special chilling shackles from dripping on one another. Spray cabinets mounted at intervals apply a thin film of moisture to exterior, interior or both surfaces. The position and type of cabinet will depend on the chilled product the customer wants to produce, as each DownFlow Plus chilling installation is tailored to specific customer requirements.
The thin film of moisture turns dry hydrophobic skin into a hydrophilic surface.
These requirements will include product weight, the lightest and heaviest products in a given flock, the temperature to which products should be cooled, end product presentation and the space available for the installation. Marel will always come up with an ideal footprint, ensuring that product is chilled as cost-effectively and sustainably as possible.
If you cut and debone most products and do not want tough breast meat, Shock/Maturation Chillling could be your answer, particularly if used in conjunction with CAS SmoothFlow controlled atmosphere stunning system and RapidRigor in-line electro-stimulation. RapidRigor is installed immediately after feather removal.
Shock/Maturation Chilling has two DownFlow chilling processes in a single chilling installation. In the first 'shock' process, very cold air is blown aggressively onto products to quickly reduce surface temperature and stop the growth of harmful bacteria. At the same time, a film of water is applied to all exterior and interior surfaces in spray cabinets mounted at intervals to the overhead track. This aids cooling and prevents products from drying out. In the much longer maturation phase, air at a higher temperature is blown gently on products. The aim is to keep temperatures for as long as possible in the range for maximum enzyme activity essential for effective maturation. Products can be in Shock/Maturation Chillinginstallations for upwards of three hours. Shear force tests have shown that when used together with modified atmosphere stunning and RapidRigor, results are arguably better than conventional maturation off-line.
In-line immersion chilling is a concept where products are dragged through a first immersion chilling phase before being finished in a DownFlow installation. This normally used in situations where a processor wants either to offer a higher value hard-scalded deep-frozen product with less water pick-up or a soft-scalded fresh product. In the European Union, this process cannot be used to make a fresh product, as the immersion chilling of product to be sold fresh is forbidden.
The process makes use of water’s ability to chill product more quickly than air. It also enables full product-by-product traceability, as products are no longer chilled off-line in a conventional immersion chill system. Marel offers two versions of the combined system with a shorter or longer initial immersion phase. When used to provide a hard-scalded deep-frozen product, it is essential to keep products wet in the second DownFlow stage, as otherwise presentation will suffer. To make the best use of space, the initial immersion phase is installed beneath the second DownFlow phase.
Finally, Marel can offer InfraChill. InfraChill is a ducted system, which blows air from evaporators mounted at the side of the system directly into the product’s cavity thereby reducing chilling time by a quarter. Unlike DownFlow, InfraChill is a single tier system and will always have a larger footprint.
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