The Cook Chill Processes
THE COOK CHILL PROCESSES
(And cook freeze processes)
Cook chill (and cook freeze) processes are usually carried out by food service departments (that are themselves supplied with some meat or meat products by the meat trader) and are not usually carried out by the meat traders themselves but, due to both the importance of the subject and the particular care that is needed in this operation, along with the care that is needed in the care and handling of the foods used in the process, it is felt that some mention of the processes should be made here. Cook chill may employ various methods of cooking in the process so; during this brief section it only referred to as ‘cooking’ no matter if it is roasting, baking, boiling, braising or stewing.
The process of cook chill can also include ‘cook in the bag’ operations where some meat may have other ingredients added prior to being sealed into a bag for cooking but more usually the term is used to refer to the fully cooked meals that are pre-prepared and are required to be re-heated to an approved temperature immediately prior to the time of consumption. Obviously such a process requires the highest possible controls in all of its operations and the full use of the principles of HACCP must be followed at all times whenever any of these processes or indeed where other similar processes are used. That said, the benefits of the system are indeed quite impressive and there can be little doubt that at the present time there are few people who have not at some time benefited from some food cooked through a cook chill system; It isn’t just large institutions such as hospitals that use the system but organisations such as airlines and, increasingly many other food establishments such as meals on wheels and also some large throughput restaurants, where both efficiency and an assured consistency is required for the large number of meals being served. In addition to the claims for an ongoing consistency of product it has been used by some large catering operations to enable dramatic cost savings in eliminating the need for all staff to work on all days of the week in the preparation area of the kitchens. An imaginary example of this is given by one of the large chiller manufacturers (Victory blast chillers of New Jersey of U.S.A.) suggesting where a restaurant serving 600 meals per week over 6 days (presuming 50 full covers at two sittings and with a turnover of one meal per cover at each sitting). The staff in this imaginary restaurant had to work at weekends and, although they were working they were not working to their full capacity. On Mondays the Restaurant was closed. The owner realising that in order to both maintain the restaurants reputation for the high quality of the meals and to be able to operate for seven days per week with no increase in staff costs they would need to approach the problem with a different perception. The option chosen was to use a cook chill procedure and just how it can work can be seen from the tables below.
Operation prior to cook chill
Mon Tues WedThurs FridaySat Sun
Meals Stored
(opening balance) 0 0 0 0 0 0 0
Meals Cooked 0 100 100 100 100 100 100
Meals Served 0 100 100 100 100 100 100
Closing Balance 0 0 0 0 0 0 0
Operation Using Cook Chill
Mon Tues WedThurs Friday SatSun
Meals Stored 0 75 50 50 125 200100 (Opening Balance)
Meals Cooked 175 75 100175 175 0 0
Meals Served 100 100 100100 100 100 100
Closing Balance 75 50 50 125 200 100 0
In addition to enabling meals that are prepared to the same standard to be served on seven days instead of six days, the owner was able to add further benefits by only having to operate the preparation and cooking work tasks in the kitchens on four days per week, (with obvious power savings with such operations) and enabling some staff to have the weekends off. Obviously, this was a hypothetical example but it does demonstrate how the process can offer some benefits.
Throughout this process, the control of the raw materials is critical. The quality must be constant and the raw foods must have been handled in the most hygienic manner possible. HACCP controls on the temperatures of refrigeration, both of the raw material and the finished product, are not only essential but are critical. All raw materials need to have a separate preparation area from the cooking area, emphasising the real need to demonstrate a ‘one way flow’ system. Risks must at all times be kept to an absolute minimum with the process and any possible risk of a back flow could lead to immeasurable damage from contamination.
During the cooking process the food must achieve an internal temperature of at least 72°C (at the thickest point) and it must maintain that temperature for a minimum of 2 minutes. Following the cooking it must be subjected to a process of rapid chilling within 30 minutes of completion of the cooking. The chilling processes used, either blast chilling, or if the food is properly enclosed in packaging, immersion in a refrigerant solution during which it must have the core temperature reduced to 3°C or less within a maximum of 90 minutes. It is said that in the case of large cuts of meat that will require portioning, they must achieve a core temperature of 10°C within 150 minutes but in view of the many advances in portioning technology it is far preferable to safeguard the integrity of the product and to ensure portioning prior to this stage and then to adhere to the earlier requirement of achieving 3°C within 90 minutes.
If it is a cook freeze operation, the freezing must commence within 30 minutes of cooking and must achieve a core temperature of at least -5°C within 90 minutes and then aim at a subsequent temperature of -20°C or less.
The pre-cooked foods that have been produced through this process must be stored at a temperature of 0°C to 2°C and in doing so can then have a shelf life of some 5 days. If the temperature of the storage rises above 4°C but keeps below 10°C it should be consumed within 12 hours. in view of such strict control on times and temperatures (on both cooking and chilling) it is necessary that the food should be labelled to give a basic description of the food plus a packing date, necessary storage temperatures and a consume by date and the temperature that the food must be reheated to before serving (which is again a core temperature of 72°C that must be achieved and held for at least 2 minutes. Once the food has been regenerated (re-heated) it should ideally be presented for consumption within 15 minutes of the completion of the re-heating process.
Frozen foods must be completely thawed under controlled condition before any attempt is made at the regeneration process (re-heating). Food that has been thawed rapidly in fast thaw cabinets should be consumed within a maximum of 24 hours and of course no food, once thawed, must be re-frozen again.
Blast chilling is yet a further developed process and is not simply a process where food is placed into a simple chiller. The blast chill process utilises the recirculation of cold air at a very low temperature but with the air moving at a high velocity. In a blast chiller, the food to be chilled is usually placed on racks that are held in a position that is in a direct line of the air flow.
The process, while being capable of producing meals ahead of demand to satisfy a given market can, if not operated properly, carry some risks. It is prudent therefore before proceeding with such a process that some advice should be sought both from a consultant who is aware of the potential problems within the process and the local environmental health department (who should be advised anyway if meals are going to be cooked and served to the public).
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