Stoneware steamers in China date back five thousand years
Steaming cooks food in pure vapor—no air pocket—so condensate forms on the surface and runs off. It can beat boiling for speed and energy because less water must heat. Yellow River Valley stoneware steamers reach as far back as about 5000 BCE.
In true steaming the food sits fully in steam without air, so vapor condenses on it and drips away. Compared with submerging food in boiling water, the method can be faster and thriftier: little water to bring up, and steam's heat transfer is excellent. Continuous boiling makes vapor that displaces air and carries energy to food held above the liquid, usually inside a lidded metal, wood, or bamboo steamer. Burning or heavy overcooking is easier to avoid, and cooks seeking less added fat often prefer it to oil-based techniques.
Some of the earliest steam cookers are stoneware from China's Yellow River Valley around 5000 BCE, with related finds in Japan's Gunma Prefecture. Chinese and East Asian cuisines popularized stacked bamboo baskets and metal inserts worldwide even where Western kitchens long underused the method. Classic setups keep ingredients separated from the rolling boil yet enclosed so steam saturates the chamber.
A 2007 USDA comparison of steaming versus boiling vegetables found folic acid and vitamin C especially sensitive. Relative to raw produce, steaming cut folic acid by about 15 percent while boiling cut it by roughly 35 percent; vitamin C fell about 15 percent with steaming and 25 percent with boiling. Numbers vary by vegetable and time, yet they illustrate why gentle vapor appeals to nutrient-minded cooks. Ancient baskets and modern stainless inserts share the same idea: cook with a cloud, not a flood.
Source: Steaming
