A typical cooking schedule for smoked meat products cooked in meat processing ovens will include most or all of the following steps: conditioning, drying, smoking, color set, cook and finish.
Conditioning
The objective of the conditioning step is to create uniform surface conditions for the entire load of product before it is cooked and smoked. In its most basic form, a conditioning step may simply be showering the load of product before cooking.
Another effective conditioning method is to run the first step of a process as a warm, high-relative humidity step. A warm, high-humidity conditioning step will create a thin layer of condensate on the cool product surfaces, resulting in uniform surface conditions for the entire load.
An example of a conditioning step would be a 15-minute step with a 110 degree F wet-bulb.
Drying
The objective of the drying step is to uniformly dry the product surface to a desired moisture level so that when smoke is applied, it will be uniformly absorbed and the desired smoked color will be developed.
More smoke will be absorbed into a moist product surface than a dry surface. For this reason, if a darker surface color is desired, the drying step should be shortened. If a lighter surface color is desired, the drying step should be lengthened. Longer drying steps will also help to minimize two-tone color formation on products cooked horizontally in an oven.
The temperature set points for the drying step will vary greatly depending on the type of product. Typical set points for a drying step would be a 120 degrees F to 160 degrees F dry-bulb temperature and a 0 degrees F to 120 degrees F wet-bulb temperature.
If a wet-bulb set point is used, the humidity valve is often turned off during the drying step so that no steam or water humidity will be injected. With the humidity valve turned off, the oven will try to satisfy the wet-bulb set point by modulating the fresh air and exhaust dampers to control the level of natural humidity (evaporated product moisture) in the oven. The use of the natural humidity alone during the drying step will help prevent any undesired condensation of moisture on the product surface during the drying step, while still maintaining a consistent wet-bulb set point from day to day and season to season.
Smoking
The smoking step can be either a wood smoke or a liquid smoke application step.
Maintaining hot, dry conditions in the oven during a wood smoke application step will enhance the color reaction between the carbonyls in the smoke and the amines in the meat. This will promote the development of the desired smoked surface appearance.
Typical set points during a wood smoking step would be 120 degrees F to 165 degrees F dry-bulb temperature and a 0 degrees F to 130 degrees F wet-bulb temperature.
If the wet bulb set point is higher for this step than the previous drying step, moisture may be condensed on the product, re-wetting the surface at the beginning of the smoking step. For this reason, it is a good idea to use the same wet-bulb set point for this step as for the drying step so as to avoid condensing moisture on the product surface at the beginning of the smoking step.
For liquid smoke application in batch ovens, the smoke is usually applied by shutting down the oven and atomizing the liquid into the oven cabinet. A liquid smoke step normally includes an atomized smoke application period followed by a short dwell time, after which the oven is restarted and the process continued. Regardless of the application time for the liquid smoke, the dwell time should not be longer than 10 minutes.
Atomized liquid smoke is sometimes applied in two steps instead of one, with a 15- to 30-minute drying step separating the two application steps. If so, the wet-bulb temperature for the drying step should be set at 0 degrees F to open the dampers and create the dry conditions that enhance smoked color development.
Applying atomized liquid smoke using two short steps is often more effective than a single long step, even if the actual atomization time is the same. For example, two 15-minute liquid smoke steps separated by a 15-minute drying step will often be more effective than a single 30-minute application step.
Color
The purpose of the color setting step is to develop and fix the smoked surface color before proceeding to the higher humidity cooking and finishing steps. During this step, hot and dry conditions should be maintained in the oven to promote the development and stabilization of the desired smoke color.
Typical set points for the color setting step would be 140 degrees F to 180 degrees F dry-bulb temperature and a 0 degrees F to 120 degrees F wet-bulb temperature. If a process includes a liquid smoke step, it is essential that a color-setting step immediately follow the liquid smoke application step to develop and set the smoked color.
To create the dry conditions that promote smoke color development and stabilization, the dampers should be open and the wet-bulb temperature should be set at 0 degrees F for this step.
In a wood-smoking process, a color setting step may not be necessary if the color has been effectively set during the smoking step. If a color setting step is used, it is a good idea to maintain the wet-bulb set point for this step the same as it was for the smoking and drying steps. This will prevent moisture condensation on the product surface.
Cooking
This cooking step is used as a transition between the low humidity/color setting step and the high humidity finishing step. Typical set points for the cooking step would be a 160 degrees F dry-bulb temperature and a 130 degrees F to 150 degrees F wet-bulb temperature. For some products, this step is unnecessary and can be omitted.
Finishing
During the finishing step, the product is cooked to its target core temperature. In this step, the wet-bulb set point should be set at or slightly higher than the target core temperature. For example, if the target core temperature for a product is 160 degrees F, then the wet-bulb set point for the finishing step should be 160 degrees F or higher. This will reduce cooking times, improve product temperature uniformity, and improve shrink uniformity. If the color has been developed and stabilized properly in the previous steps, no adverse effects on the product surface color should be caused by the high-wet-bulb temperature.
Typical set points for the finishing step would be 170 degrees F to 200 degrees F dry-bulb temperature and a 155 F degrees to 165 F degrees wet-bulb temperature.
A variety of smoked meat products are produced every day using many variations of the pre-mentioned guidelines. If different cooking and smoking processes were not used, it would be difficult to develop and market products with unique identities. Even so, if the guidelines are followed when developing or modifying cooking and smoking schedules, the chances of achieving a successful and more consistent process will be improved.
This presentation was delivered by Robert Hanson of Lodi, Wis.-based Alkar Technical Development during a three-day session at the Viskase Corp. Food Science and Quality Institute in Chicago. This seminar was co-sponsored by the American Meat Science Association.