Unsweetened sugars, such as starch, cellulose, hemicellulose and pectin. Are these sweets still called sugar if they are not sweet? The answer is yes. Chemically, sugar, also known as "carbohydrate", is a polyhydroxy aldehyde and polyhydroxy ketone compound composed of carbon, hydrogen and oxygen. According to its composition, it can be divided into monosaccharide, disaccharide and polysaccharide. Monosaccharide and disaccharide have significant sweetness, while polysaccharide generally has no sweetness.

Why is polysaccharide not sweet? Because polysaccharide is polymerized from monosaccharide, its molecular weight is extremely high. For example, amylose has a molecular weight of 3-65,438+600,000 and contains 200-980 glucose residues. The molecular weight of amylopectin is10-100000, and it contains 600-6000 glucose residues. Because the molecular weight of polysaccharide increases, the solubility decreases, and because of the increase of polymerization degree, human taste nerve can only perceive one sugar residue, which makes polysaccharide not have obvious sweetness.

What's the value of sugar but not sweet? Scientific research shows that polysaccharides exist widely in human body, some as nutrients and some as structural substances, which is of great significance for maintaining normal physiological functions of human body. For example, starch, as the main component of cereals and potatoes, is the main source of human energy. It is determined that each gram of starch can produce 17.49 kilojoules of energy. Cellulose, hemicellulose and pectin have no nutritional value to polysaccharide itself, but they are helpful to the digestion process, such as promoting gastrointestinal peristalsis, facilitating excretion and reducing the content of cholesterol in blood.

Modern medical research also shows that fibrous polysaccharide can also excrete carcinogenic poisons and a large number of microorganisms. Therefore, the international food market should pay special attention to the content of fibrous polysaccharide in food.

Then there are some non-sugar substances, which taste very sweet, such as saccharin, xylitol, stevioside, liquiritin and so on. These non-sugar substances have the advantages of high sweetness and low calorie, and most of them have medical and health care functions. With the prevalence of "diseases of wealth" (hypertension, heart disease and diabetes) in the world, sugar-free sweeteners have broad development prospects.

Non-sugar sweeteners can be divided into four categories according to their sources and components, namely synthetic sweeteners (such as saccharin), non-sugar natural sweeteners (such as stevioside), naturally derived sweeteners (such as aspartame) and sugar alcohol sweeteners (such as xylitol).

Stevioside is a natural component extracted from plants, and its sweetness is 300 times that of sucrose. It has the effects of lowering blood pressure, promoting growth and wilting.

Proteoglycan is a sweetener made from unsweetened non-sugar natural substances. Its sweetness is 150 times that of sucrose, and it can be doubled by adding salt.

Xylitol exists in many plants and is made from reduced log sugar in industry, and its sweetness is slightly higher than sucrose. Because it is not affected by insulin during metabolism, it is an ideal sweetener in therapeutic food for diabetic patients.

It should be pointed out that saccharin, as a non-sugar sweetener, has a high sweetness. It is nontoxic when eaten in small quantities, but it has no nutritional value. A large amount of food will have a certain impact on human health, so it should be limited. China stipulates that saccharin is forbidden to be used in baby food, and the amount used in other foods should not exceed 0. 15g/kg.