Cold Rooms – what’s hot and what’s not!
Each cold room’s blueprint has to be evaluated and planned meticulously before deciding on the type and size, the materials from which it is made, and the room’s temperature control and maintenance.
A butchery cold store basically incorporates a reception area, where fresh meat is received and inspected at a controlled room temperature between 8°C and 12°C; despatch and holding rooms at about 2°C to 4°C; and one or several cold chambers for meat and offal at appropriate storage temperature.
The cold store may also incorporate a cutting and deboning room at a temperature between 8°C and 12°C, and a packaging room and a sales room, both with a low temperature at around 5°C to 7°C. For freezing and frozen storage, there are freezing tunnels or rooms at temperatures ranging from -30°C to -45°C.
When consulting a cold room manufacturer, the following questions should be asked before the design process is discussed:
1. What are the minimum and maximum temperatures?
2. How quickly must the temperatures be achieved?
3. What are the humidity requirements? (In most cold rooms, humidity control is not essential. There are, however, two reasons end users sometimes include humidity control in their specification: to reduce excessive defrost cycles or to avoid problems with humidity-sensitive products.)
4. What is the required size of the cold room? (When determining room dimensions, the wall thickness that is required to contain the correct temperatures must be kept in mind.)
5. What will the refrigeration loading be? If the load is constant, the refrigeration equipment is sized for wall and infiltration losses. If large objects will be cooled or refrigerated, larger capacity refrigeration will be required. One should also consider the frequency of the door being opened.
6. How can I maintain the reliability of my cold room? (If reliability is critical there should be standby power.)
7. Where will the compressor be located? (A compressor should never be positioned on top of a pre-fabricated building).
Building many chambers of a small size, particularly for meat products, is of no value. Chilled meats of different types (beef, pork or mutton) can be stored in the same room, as they do not present temperature or tainting incompatibilities. Frozen meats have even less problems.
A design that opts for fewer, larger chambers represents economical benefits. Firstly, many divisional walls and doors are eliminated, and, secondly, refrigeration and control equipment is simplified and reduced, cutting down on investment and running costs. Large chambers also allow easier control of temperature, relative humidity and better use of storage space.
The storage requirements of the produce, rules for loading, maintenance and hygiene, and the running and sustainment of the refrigeration equipment are of great significance.
Hygiene must be maintained after storage, during transport and distribution. Cold chambers intended for meat chilling and chilled storage must be kept in a strictly hygienic condition, as microbial invasion is a serious risk.
The following operations are essential:
• immediately eliminate all waste in a cold room;
• each time a room is emptied, or after re-warming rooms at low temperature, wash floors and walls with detergent and hot water, rinse them with clean water, and spray with a solution containing active chlorine;
• clean pallets and storage containers every four months;
• disinfect chilled storage rooms for 48 hours at least twice a year and frozen produce rooms when they are emptied;
• before storing animal products in rooms that have contained strongly fragrant fruits and vegetables, deodorise by washing, provide prolonged ventilation and finally spray with a solution containing ammonium salts.
The next important factor to consider is the type of fridges and freezers best suited to your needs. A walk-in cooler, freezer or a combination of both is perfect, as it is large enough to accommodate the storage of bulk perishable foods while making them easy to locate, load and unload. But it is a big expense and one you don’t want to regret.
To help you find the walk-in cooler, freezer or combination that fits your needs and budget, some of the most important facts to assist you in your decision are:
• know how much storage space you’ll need;
• make sure you have enough space to have a walk-in installed that will be convenient to work areas;
• check to make sure that accessible drain lines are available;
• determine the condition of the floor so you’ll know whether it can bear the weight of the model you need;
• make sure you can properly ventilate the heat produced by the system.
The size of a walk-in has a lot to do with the price. Walk-ins can range from a few metres by a few metres to the size of a warehouse. A low up-front cost may be what you’re looking for, but, in the long run, you might end up paying what you would have for a larger and more efficient high-end model in energy bills.
There are different types of walk-ins: those that cool and those that freeze foods, as well as combination units that do both. Walk-ins can be located inside or outside of the butchery, on existing floors or prefabricated flooring.
Some of the standard features are sliding or hinged doors with airtight seals, a left or right-hinged door, deadbolt locking handles, inside door releases, or reinforced doorframes with heavy-duty hinges. PVC-stripped curtains and glass doors are also available.
Most walk-ins are made with prefabricated tongue and groove polystyrene-insulated panels made of aluminum, stainless steel, galvanised steel or high-density urethane or fibreglass. Panel insulation is available in different grades of thickness. The panels are assembled from floor to ceiling, without joints.
Condensers can be placed inside or outside of the premises. An indoor compressor/motor condenser system will cost less to install and is easier to maintain and clean, but the heat from the unit will be ejected into the same room, which will increase the room temperature and cause your air conditioning system to work harder. An outdoor compressor/motor condenser system will prevent heat build-up and eliminate noise, and will also operate more efficiently in cooler weather.
Meat stored at just below 2˚C and 80-85% relative humidity maintains maximum weight and quality. Under these conditions ageing is slowed down and the growth of bacteria is greatly reduced. Whilst modern walk-in cold room technology has advanced to the point where the foregoing ideal temperature and humidity levels can be pre-set, the latter cannot be maintained 24/7.
This is due to frequent opening of doors (even left open for extended periods during peak production); an ageing and over-worked refrigeration plant; irregular and non-existent planned maintenance programmes of such a plant; constant and high volumes of traffic in and out of the cold room; ever fluctuating levels of stock holding; and finally, meat being stored with other non-meat products.
These conditions lead to moisture build-up within cold rooms and, ultimately, pockets of latent heat, which inevitably results in temperatures exceeding 2˚C, as well as a variance between upper internal and lower level air temperatures, where the former is colder than the latter.
A simple, but effective, test is to stand in a cold room (with the door shut) for 30 seconds and feel the difference between the upper and lower strata temperatures – usually one only feels cold from the breast upwards, whilst from the arm pits down the air is not as cold! The foregoing can be reduced (but not eliminated) by either plastic or air curtain fitment.
Suppliers in South Africa include Matador Refrigeration , Echo Coldrooms, Cool Africa and Africhill to name but a few.
