Preservation and Storage Methods for Chinese Yam, a Medicinal and Edible Crop
Chinese yam contains protein, carbohydrates, vitamins, fats, choline, amylase, and other substances, as well as essential minerals and trace elements such as iodine, calcium, iron, and phosphorus. It has health benefits including tonifying the lungs, strengthening the kidneys, and boosting essence, making it a premium vegetable used both as medicine and food.
1. Storage and preservation conditions
(1) Storage characteristics. Chinese yam is a vegetable that tolerates low-temperature, low-humidity storage and also has a physiological dormancy period. However, once the dormancy period ends during storage, physiological metabolism becomes more active, and fibrous roots emerge from the tuber's surface. At this point, if storage conditions are unsuitable, rot and deterioration easily occur. Therefore, extending the dormancy period of Chinese yam is the key to extending its storage life.
(2) Post-harvest handling. Chinese yams intended for storage should be thick and sturdy, intact with both head and tail, with no mud on the surface, no fibrous roots, no wounds or scars, no pest damage, and no frost injury. Before being placed into storage, they should be spread out and air-dried in the shade so that the outer skin becomes slightly dry and hardened.
(3) Suitable storage conditions. Temperature 0-2°C, relative humidity 80%-85%. Under these environmental conditions, they can be stored for 150-200 days.
2. Storage methods
(1) Pit storage. Use fine mud or river sand to surround and bury the yams in a pile on the spot. The method is as follows: on the floor of a well-ventilated room, cellar, or warehouse with low humidity, build a storage pit about 1 m high with bricks. Spread a layer of dry fine soil or dry sand about 10 cm thick that has been sun-disinfected on the bottom of the pit, then place the selected and thoroughly air-dried yams flat on the soil (sand), adding one layer of yams and one layer of soil (sand) until the pile is about 10 cm below the pit opening, then seal with dry fine soil or sand. After burial, generally conduct a sampling inspection about once a month. When turning and inspecting, handle them gently and do not scratch the tuber skin; remove any diseased ones promptly to prevent spread. If the mud (sand) has too high a moisture content, turn the pile earlier.
The containers for pit storage of Chinese yam can also be bamboo baskets, slatted crates, and the like. The method is as follows: first line the bottom and sides of the box or basket with disinfected paper, then add one layer of yams and one layer of soil (sand) until about 5 cm below the opening, and cover with soil (sand). The timing for turning and inspecting can be determined according to the preservation condition of the yams. Using a crock for storage is even simpler: just first spread a layer of mud and sand on the bottom of the crock, then add one layer of yams and one layer of soil (sand) until 7-10 cm below the crock opening, and seal the opening with soil (sand).
(2) Basket storage. Use sun-disinfected rice straw or wheat straw (wheat straw is best) to line the bottom and sides of disinfected baskets (boxes), then stack the selected yams layer by layer until 80% full, cover the top with wheat straw up to the basket (box) opening, and stack them in a straddle pattern in a ventilated storage warehouse, generally to a height of 3 wicker baskets or 4 slatted crates. To prevent ground moisture from affecting the tubers, when stacking, place bricks or wooden boards under the bottom basket (box) so as to leave a gap of about 10 cm from the ground. The warehouse should be kept cool and dry.
(3) Cold storage. Place the selected yams into slatted crates lined with four or five layers of paper, seal the crate openings with paper, then stack them in rows or place them on shelves in a cold storage facility. Regulate the storage temperature to 0-2°C and the relative humidity to 80%-85%, and pay attention to ventilation. They can be stored for more than half a year.