Onion, a 2-year-old herb. There are many claims about the origin of onions, but most people think that onions are found in the plateau regions of southwestern Asia, Central Asia, Asia, Asia, Asia and Asia, Asia and Asia. The origin of the onion has been more than 5,000 years. It reached Egypt in 1000 BC and was later spread to the Mediterranean. It was introduced to the United States in the 16th century, Japan in the 17th century, and China in the early 20th century. Onions are widely distributed in our country and are cultivated in all parts of the country, and the planting area is still expanding. It is one of the main vegetables in our country. China has become one of the four countries with a large onion production volume (China, India, the United States, and Japan). The planting areas in China are mainly Shandong, Gansu, Inner Mongolia and Xinjiang.
Nutrients
The onion has a fattened fleshy bulb as an edible organ and is rich in nutrients. It is determined that each 100 grams of fresh onion has a moisture content of about 88 grams, protein of 1 to 1.8 grams, fat of 0.3 to 0.5 grams, carbohydrate of 5 to 8 grams, and crude fiber. 0.5 g, heat 130 kJ, calcium 12 mg, phosphorus 46 mg, iron 0.6 mg, vitamin C 14 mg, niacin 0.5 mg, riboflavin 0.05 mg, thiamine 0.08 mg, carotene 1.2 mg. It also contains caffeic acid, sinapinic acid, cinnamic acid, citrates, polysaccharides, and various amino acids. Volatile oil is rich in allicin, thiol, trisulfide and so on. Flower buds, pollen, anthers, etc. all contain carotene. The tearing ingredient of onion is alliin, and the S-propenyl-L-hemisteine ​​hydrosulfide contained in the onion is a precursor of the ring alliin. Under alkaline conditions, the ring can be synthesized Amino acid.