How to choose iron stick yam
Compared with common yam, iron stick yam has the characteristics of short, thin, long burr, head and tail and detail. Iron stick yam is generally no more than meters, but its two fingers are thick, unlike other yams. If the arms are round, they are often fat and long.
Iron stick yam is called iron stick yam because it is slender and compact, and it is not easy to break when hitting each other (somewhat exaggerated). Because it is short and thin, it is usually sold intact, unlike other yams, which have to be cut into pieces because of their body length.
Iron stick yam has long burrs, dark skin color and sometimes purple spots. Iron stick yam is often a big head and a small head, dragging a slender tail, sometimes the tail will account for half the length. Not as uniform as ordinary yam. Iron-stick yam has a fine section, the color is like china white, the quality is like porcelain, and the white is like porcelain jade. Ordinary yam is big, sparse in texture, with no porcelain color reflection and obvious granularity.
Iron stick yam segment is not easy to turn yellow. Ordinary yam will turn yellow soon if it is cut and left untreated. When cooked, it is very resistant to cooking and does not rot for a long time. Delicate taste, flour and powder, sweet and delicious, slightly medicinal.
How to choose common yam
We usually eat the most common yam, which is relatively cheap, can be used as both food and medicine, and even enter the homes of ordinary people.
Ordinary yam should be thick and hairy (so the taste will be dull), with small water head (high dry matter content and easy storage), and the cut surface is not easy to turn yellow (easy storage), and there is mucus after cutting (yam polysaccharide and glycoprotein are high in content and high in nutritional value).
The cross section is red and hard, and the juice is not as sticky as water, but frozen. It's best not to choose.
How to prevent yam from turning black when cooking?
After the yam is cut, the polyphenols in it will turn yellow when it meets the oxygen in the air and turn black when it meets the iron in the iron pot under the action of polyphenol oxidase. In order to prevent the discoloration of yam, yam can be pretreated and cooked after polyphenol oxidase fails. Yes: ① blanch after cutting; (2) Steam the skin in a steamer for one minute or bite it in a microwave oven for one minute.
How much yam is appropriate to eat every day?
The daily therapeutic dose of processed yam is 15 ~ 30g, and the health-care dose is 10 ~ 20g.
Fresh yam daily100 ~ 200g. Fresh yam is easy to combine with minerals such as calcium because polyphenols are not oxidized, causing constipation. If this happens, stop eating for a day or two.