What Exactly Is the Latest Chinese Yam? A Detailed Explanation
Chinese yam is a medicinal herb recorded in "Chinese Materia Medica", also known as shuyu, tushu, shanshuyu, Huai Chinese yam, Huaishan, white Chinese yam, etc. Its medicinal source is the dried rhizome of the twining herbaceous vine Chinese yam of the Dioscoreaceae family. The best comes from Huaiqing Prefecture in Henan (present-day Bo'ai, Wuzhi, and Wenxian), known as Huai Chinese yam. Huai Chinese yam was exhibited at the 1914 Panama Universal Exposition, and thus became famous at home and abroad, and has been exported year after year to more than ten countries and regions including the United Kingdom and the United States.
The tuber of Chinese yam is long and cylindrical, growing vertically, reaching more than 1 m in length, and white when dry in cross-section. The stem is usually purplish red, dextrorse, and hairless. The leaves are simple, alternate in the lower part of the stem, opposite above the middle, rarely in whorls of 3; the leaf blades are highly variable, from ovate-triangular to broadly ovate or hastate. It is dioecious; the male inflorescence is a spike, and the female inflorescence is a spike. The capsule does not reflex, and is trigonous-flatly rounded or trigonous-rounded; the seeds are borne in the middle of the central axis of each locule. The flowering period is June to September, and the fruiting period is July to November.
Chinese yam prefers high temperature and dryness; the tuber begins to sprout at 100°C, the optimum temperature for stem and leaf growth is 25-28°C, and the optimum soil temperature for tuber growth is 20-24°C. The leaves and vines die when exposed to frost, and the tuber can tolerate a low temperature of -15°C. Short-day conditions promote the formation of tubers and aerial tubers. It is not strict about soil, but the best is fertile, loose sandy loam with strong water retention and a deep soil layer, with the groundwater table below 1 m and a soil pH between 6.0 and 8.0.
As a Chinese medicinal herb used both as medicine and food, Chinese yam has different regional characteristics due to the influence of regional climate features, geological characteristics, growth habits, and other factors. The main producing areas are Bo'ai, Wuzhi, Wenxian, and other places in Henan, and it is also cultivated in Shanxi, Shaanxi, Shandong, Hebei, Zhejiang, Hunan, Sichuan, Yunnan, Guizhou, Guangxi, and other places. Several major producing areas, mainly in Guangxi, Hebei, and Henan, form the main domestic Chinese yam cultivation regions.
Chinese yam is one of the earliest plants eaten by humans. As early as the Tang Dynasty, the poem by Du Fu, the sage of poetry, contains the famous line “fill the belly with Chinese yam”. The tuber is thick and juicy, sweet and mealy, and somewhat sticky; it is delicious whether eaten raw or cooked. On average, the tuber contains 14.48% crude protein, 3.48% crude fiber, 43.7% starch, 1.14% sugar, 2.62% potassium, 0.2% phosphorus, 0.2% calcium, 0.14% magnesium, and 5.51% ash. Of the 18 amino acids needed by humans, Chinese yam contains 16.
The sticky substance in Chinese yam is mucin formed by the combination of mannan and globulin. It has effects such as nourishing and strengthening, aiding digestion, reducing spontaneous sweating, and stopping diarrhea. It mainly treats deficiency diarrhea of the spleen, cough due to lung deficiency, diabetes with thirst, short and frequent urination, seminal emission, leukorrhea in women, and chronic enteritis with indigestion, and other conditions. It is most suitable to take together with lingzhi (Ganoderma lucidum), and has the effect of preventing and treating diabetes, with great development prospects in the food industry and processing industry.