Plateau phase at low temperature grilling?
Why are there plateau phases (no rising core temperature) at low temperature grilling?
Answer: Plateau phases (English : stall) relate to the core temperatures of large pieces of meat which are cooked sometimes up to 24 hours at temperatures of 90-110 °C in a smoker grill, kettle grill, oven etc. This type of grilling is particularly widespread in the USA and describes the Original American Barbecue. Examples of this are beef brisket, pulled pork (pork leg, neck) or Spare Ribs. The cooking process is usually tracked with a thermometer which is inserted in the centre of the piece of meat and remains there. At the beginning the core temperature gradually increases, but at 70 °C something strange happens - the plateau phase.
During this up to 4 hour long phase the temperature doesn`t increase, sometimes it even falls slightly. Previously it was believed that this was to do with the melting of collagen and the energy required for this. The collagen holds the meat together, and the slow cooking process changes it into Gelatine and makes the meat as tender as butter. That theory is incorrect.
The plateau phase occurs when the wet bulb temperature is higher than the temperature of the meat. The wet bulb temperature is the lowest temperature obtained by the evaporation of water into the air under constant pressure (evaporative cooling). The higher the humidity in the smoker grill, the higher the wet bulb temperature. As soon as the surface of the meat dries out and all moisture is emitted, the wet bulb temperature sinks again and the core temperature continues to rise. Through mopping the plateau phases is even extended, since the surface of the meat is artificially moistened and thus the meat is cooled through the evaporative cooling. As long as the meat can evaporate enough moisture to cool itself and to keep the humidity in the smoker grill, the plateau phase will continue. Even a bowl of water in the cooking chamber can indirectly prolong the plateau phase, as the wet bulb temperature remains high due to the high humidity. If you wrap a piece of meat in oil, then the plateau phase does not apply. This phenomenon can be proven using 2 identical pieces of meat, one with and one without foil.