What is Chinese Yam
In traditional Chinese medicine and home cooking recipes, Chinese yam is always present. This remarkable plant, which can be used both as medicine and food, hides many unknown secrets. Let's uncover the mysteries of the differences between varieties by starting with its biological characteristics.
I. Biological Characteristics of Chinese Yam
1. Unique Morphological Features
The tubers of Dioscoreaceae plants are usually cylindrical, with a light yellow outer covering on the epidermis and dense thin roots in the longitudinal grooves on the surface. The cross-section reveals a crystal clear milky white flesh, and the mucilage is rich in active ingredients such as dioscin. Mature tubers are generally 20-30 centimeters in length, with significant differences in diameter, which is an important indicator for distinguishing varieties.
2. Gold Planting Belt Distribution
The 34th parallel north forms a natural planting corridor, with Henan Wenxian, Hebei Lixian, and Guangxi Guiping as the three major core production areas. The ecological conditions of these areas, with an average annual temperature of 15-18°C and annual precipitation of 600-800 millimeters, combined with the alternating geological structure of sandy loam and cinnamon soil, create the excellent quality of authentic Chinese yam.
3. Growth Environment Preferences
As a typical short-day crop, Chinese yam is extremely sensitive to temperature changes. The soil layer depth needs to reach more than 80 centimeters, and a slightly acidic environment with a pH value of 6.0-7.0 is most conducive to tuber expansion. It is worth noting that when the day-night temperature difference exceeds 10°C, the starch conversion efficiency of the tubers increases by over 30%.
II. Variety Classification Atlas
1. Two Basic Categories
Common Chinese yam (Dioscorea opposita) and sweet potato (Dioscorea alata) form the main body of the cultivation system. The former focuses on the medicinal market, while the latter is more inclined towards fresh food consumption. The D-P variety, cultivated through hybridization in recent years, has increased the yield by more than 40%.
2. Five Characteristic Varieties
Iron stick yam is famous for its dense rust spots and has a mucin protein content as high as 2.3%; hemp yam has prominent skin protuberances and strong adaptability; water yam has a water content of over 85%, crisp and tender; small white mouth variety has a creamy white core color and does not disintegrate after boiling; fine hair yam is characterized by fine and dense roots less than 0.3 millimeters in diameter.
III. Value of Food and Medicine
Modern research has confirmed that the polysaccharides in Chinese yam can inhibit α-glucosidase by 68%, making it a natural hypoglycemic food. The allantoin rich in the mucilage can accelerate the regeneration of epidermal cells and is widely used in traditional Chinese external application therapy. There are significant differences in nutritional components between different varieties, such as the selenium content in iron stick yam being three times that of common varieties.
From the loess iron stick yam in the north to the water yam in the south, each variety tells a unique regional story. Understanding these differences can not only improve cooking skills but also allow for precise selection based on health maintenance needs. Next time you make a purchase, take a close look at the surface texture and cross-section characteristics to appreciate the exquisite design of nature.