Fat choy is a blue-green algae that looks like black human hair and is used as an ingredient in Chinese cuisine. Also known as Nostoc flagelliforme, this single-celled algae is a a type of photosynthetic bacteria that grows on land. It primarily grows on the topsoils of the Gobi desert in the Qinghai Plateau, but it can also be found in the dry regions of other countries. It resembles steel wool in appearance and is associated with good fortune in Chinese culture because it sounds quite similar to a form of greeting that wishes the other more prosperity. As a result, it is consumed in large quantities during the Chinese New Year.
It is tradition to wish friends and family "Gung Hei Fat Choy" in the New Year, which translates roughly as "strike a fortune." This has contributed to its popularity in Chinese cooking, though its nutritional value remains dubious. Used in many dishes as an alternative to noodles, fat choy needs to be soaked for quite a while before it can be cooked. Once soaked, it gains the texture of very fine vermicelli and absorbs the flavors of the liquid it is cooked in. When stored in an airtight package, it remains edible for up to a year.
This cyanobacteria is found in its natural environment as gelatinous colonies and grows very slowly. It forms a matlike growth on the topsoil, and it is critical to the health of the grasslands and dry lands it lives in because it protects them from erosion. It is one of the oldest single-celled forms of life and releases oxygen into its surroundings. Containing numerous filaments covered by sheaths that help it retain water and stay hydrated, this bacterium has adapted itself to thrive in the most inhospitable environments on very little water.
Indiscriminate harvesting of this terrestrial algae has lead to vast tracts of land becoming deserts. The severely damaged soil takes around two to three years to recover because the harvesting process destroys all surface vegetation. Some countries have taken big steps toward limiting the harvest, which has raised its price and made it a valuable commodity on the black market. The Chinese government banned the harvesting, processing, and selling of fat choy in 2000. It is still sold in shops in Taiwan, Hong Kong, and other places overseas.
A difficult material to obtain, some sellers adulterate it with strands made from other starches. Original fat choy is dark green in color; adulterated strands, though, look more black. One way to determine the quality of the product is to simmer it in water. While the real thing stands up to more than half an hour of simmering in water, adulterated fat choy rapidly disintegrates. Adulterated strands also turn black when treated with iodine and can be identified quite quickly as fake under a microscope.