Persian rice cooker have a significantly larger capacity than home rice cookers (5 to 10 liters) and are more commonly used for commercial purposes. They must be connected directly to a fuel source (either a natural gas line or a portable propane source) and do not require an electrical power supply.
When cooking in a commercial setting, where quality, quantity, and speed are important factors, gas powered rice cookers offer several benefits. The gas powered flame source heats the cooking pot much more quickly than electrical power sources. Cooking at higher temperatures allows the rice to absorb water faster and cook more quickly, yielding a sweeter and more firm final product. Due to the amount of rice being cooked at one time, electrical powered cookers are not able to heat the cooking pot fast enough. This usually results in uneven cooking of the overall batch of rice-often leading to mushy or burnt rice on the bottom of the pot and sometimes under-cooked rice at the middle and top of the cooking pot. Finally, being able to heat the cooking pot to a higher temperature relatively quickly allows the rice to cook faster and steam properly, resulting in a better quality batch of rice.
Most, if not all, persian rice cooker use an heat based automatic shut-off system. The basic principle of these systems is such that gas flow into the burner is halted once a specific temperature is reached, resulting in the burner flame to go out.
A relatively new concept is the commercial gas pressure cooker. These cookers use pressure cooking to produce a uniformly cooked batch of rice. Cooking rice in a pressure cooker allows the rice to cook under more optimal conditions.
Ideal cooking for rice employs a method of a fast heating source along with a uniform delivery of that heat. A gas powered pressure cooking system is able to use a flame heat source to heat the cooking vessel quickly and the pressure cooker is able to heat the internal cooking environment to higher than the boiling point of water in a uniform manner.