Glucose is the most common and familiar monosaccharide, also known as glucose or blood sugar, and it is one of the most abundant compounds in nature. In nature, it is synthesized by water and carbon dioxide through photosynthesis. Because it was originally a crystal separated from grape juice, it was named "glucose". Glucose exists in human plasma and lymph. The content of glucose in normal blood can reach 0.08% ~ 0. 1%.
Glucose exists in free form in plant juices, especially in fruits and honey. The large-scale production method of glucose is not extracted from fruits and honey with high glucose content, because the cost is too high.
In industrial production, glucose is made from starch contained in corn and potatoes. In the past, the starch contained in corn and potato was hydrolyzed with 0.25% ~ 0.5% dilute hydrochloric acid at 100℃ to generate glucose aqueous solution, and glucose crystals were obtained after concentration. At present, glucose is almost completely produced by enzymatic hydrolysis, that is, under the action of starch glucoamylase, starch in corn and potato is hydrolyzed to obtain 90% glucose aqueous solution, and glucose crystals can be obtained after concentration.
The molecular structure of glucose was determined by German chemist Fischer in the19th century. Glucose contains 6 carbon atoms in its molecule and is a hexose. Glucose molecule also contains aldehyde group (-CHO), which is reducible, so glucose is a reducing sugar.
Glucose is an indispensable substance in life activities, which can directly participate in the metabolic process in the human body. In the digestive tract, glucose is more easily absorbed than any other monosaccharide, and can be directly used by human tissues after absorption. Oligosaccharides (such as sucrose) and polysaccharides (such as starch) ingested by human body must also be converted into glucose to be absorbed and utilized by human tissues.
Glucose can be oxidized into carbon dioxide and water by oxygen in human body, and this reaction releases a certain amount of heat. When each gram of glucose is oxidized to carbon dioxide and water, it releases the heat of 17. 1KJ, and 50% of the energy needed by humans and animals comes from glucose.
Glucose is an important industrial raw material, its sweetness is about 3/4 of sucrose, and it is mainly used in food industry, such as the production of bread, candy, cakes and drinks. In medical treatment, glucose is widely used in patients' infusion, because glucose is easily absorbed directly and can be used as a nutritional product for patients. Glucose can produce gluconic acid when it is oxidized, and calcium gluconate is a drug that can effectively provide calcium ions. Hexanediol can be produced when glucose is reduced, which is the raw material for synthesizing vitamin C.