Cooking Chinese Style

Estimates of Chinese meals include more than 3,000 varieties, possibly more meal types than the total number of meals by all other cultures combined. Many of the Chinese dishes use meats cut into small cubes or other small volumes. Certainly, these small volumes are much easier to eat with chopsticks. Are there any significant scientific reasons for cutting up the meats into small volumes?

Answer

There are at least two good reasons for cutting up meats into small volumes: (1) marinades and spices penetrate more thoroughly into the meat in a shorter time because the inner-volume elements are closer to the surface; (2) smaller chunks cook faster and therefore require less fuel. The faster cooking occurs because (a) the inside of the small cube is closer to the heat source than for a thicker piece and (b) the meat is tumbled during stir-frying, exposing different small surfaces to the higher temperature direction. The temperature sensed by the meat tends to decrease with distance from the thermal energy source, in this case the pan bottom.

The amount of cooking experienced by a small volume of interior meat is proportional to the temperature experienced and the duration of cooking at this temperature. Both of these quantities are changing during the cooking process. In addition, the thermal conductivity and the thermal heat capacity of the meat are changing because the meat material itself is changing. For example, if the outside becomes charred, its thermal conductivity is significantly reduced, so that the transmission of thermal energy decreases compared to its prior rate. Therefore hamburgers, which must be cooked thoroughly inside to kill the bacteria on the surfaces of the ground up meat, must never be charred on the outside because the inside will tend to remain uncooked or partially cooked, creating a dangerous eating condition.

The physics here is found in any high school physics text, but the application to cooking was devised millennia ago by ancient chefs who desired a particular result with perhaps a minimum of fuel expenditure. Certainly one can go to the other extreme by slow-roasting a whole carcass in a revolving spit or in a hot ember-lined pit in the ground.