Oligosaccharides, also known as oligosaccharides or oligosaccharides, are a new functional sugar source. Oligosaccharides integrate nutrition, health care and dietotherapy, and are widely used in food, health products, beverages, medicinefeed additive And other fields.[1]
It is a new functional sugar source to replace sucrose and a new generation of functional food facing the 21st century.It is a new product with a wide range of applications and application prospects, which is quite popular internationally in recent years.The United States, Japan, Europe and other places all have large-scale production. The development and application of oligosaccharides in China began in the mid-1990s, with rapid development.[1]
Basic composition
Oligosaccharides in the form of existence refer to 2-10Glycosidic bondThe glycoside bond of the polymerized compound is amonosaccharideAnd one of another monosaccharidehydroxylFormed by dehydration and condensation.They are often covalently bound to proteins or lipids and exist in the form of glycoproteins or glycolipids.[1]Oligosaccharides usually connect 2-4 monosaccharides through glycosidic bonds to form oligomers, which includefunctional oligosaccharide With ordinary oligosaccharides, this kind of oligosaccharide has the following common characteristics: it is difficult to be digested and absorbed by the gastrointestinal tract, low sweetness, low calorie, and basically does not increase blood sugar and lipids.[1]
The most common oligosaccharides are disaccharides, also called disaccharides, which are formed by the combination of two monosaccharides through glycosidic bonds. The covalent bonds connecting them are mainly of two types: N-glycosidic bonds and O-glycosidic bonds.[1]
1. N-glycoside bond type: oligosaccharide chain andpolypeptideOnAsnOfaminoto be connected.There are three main types of these oligosaccharide chains: high mannose type, hybrid type and complex type.[1]
2. O-glycoside bond type, oligosaccharide chain and polypeptide chainSerorThrThe hydroxyl group of the membrane lipid is connected with the hydroxyl group of the membrane lipid.Oligosaccharides are found in garlic, onion, burdock, asparagus, beans, honey and other foods.[1]
Oligosaccharides can be extracted from natural foods, or synthesized by starch and disaccharides (such as sucrose) using biochemical technology and enzyme reaction.[2]
Oligosaccharides cannot be destroyed by human stomach acid, nor can they be decomposed by digestive enzymes.But it can be fermented by bacteria in the intestines and converted intoShort chain fatty acidsAnd lactic acid.With the different fermentation mode and absorption state in colon, these can not be directly absorbed, but can be fermentedcarbohydrateEach gram can produce 0-2.5 calories.However, the physiological activity of oligosaccharides has attracted more attention.[2]
name
OligosaccharideSystem nomenclature,, due to nonReducing sugarIt is different from reducing sugar.Non reducing sugars are named according to glycosides. For example, sucrose is a non reducing disaccharide, which can be namedGlucosideOr fructose glycoside, as shown in the figure Systematic Naming of Sucrose, both of these names are correct.The glycosidic bond consists of twoSemiacetal hydroxylIt is formed between, and the position is clear, so it is unnecessary to use numbers to indicate.[3]
Systematic nomenclature of sucrose
The nomenclature of non reducing oligosaccharides above trisaccharide is similar to that of disaccharides, which is carried out in the way of glycosyl glycosyl glycoside.Use two numbers to mark the relevant carbon atoms connected by the glycoside bond, place them between the names of sugar groups, and separate them with an arrow in a bracket. The direction of the arrow is from the semi acetal hydroxyl carbon atom to the alcohol hydroxyl carbon atom.As shown in the figure "Systematic naming of raffinose":[3]
Systematic nomenclature of raffinose
The systematic naming of reducing disaccharides is carried out in the way that one sugar group replaces the alcohol hydroxyl group of another monosaccharide. Starting from the non reducing sugar group, numbers are used to indicate the position of the alcohol hydroxyl group to be replaced, and the name of the sugar to be replaced is added.Two numbers can also be used to indicate the relevant carbon atoms connected by the glycoside bond, which are placed in brackets and separated by an arrow. The direction of the arrow is from the semi acetal hydroxyl carbon atom to the alcohol hydroxyl carbon atom.As shown in the figure Systematic Naming of α - Lactose:[3]
Systematic nomenclature of α - lactose
The systematic nomenclature of reducing oligosaccharides above disaccharides is similar to disaccharides.It is carried out in a sugar sugar sugar way.Starting from the name of non reducing sugar group, the name of another sugar group in the sequence is followed by the name of reducing sugar group. Between the name of sugar group and the name of sugar group, parentheses and numbers are used to indicate the position of connecting carbon atoms.As shown in the figure "Systematic naming of α - maltotriose":[3]
Systematic nomenclature of α - maltotriose
classification
There are two main types of oligosaccharides. One is maltooligosaccharide, which has the characteristics of easy digestion, low sweetness and low permeability, and can extend the energy supply time, enhance the endurance of the body, resist fatigue and other functions. The human body is prone to dehydration after heavy (or heavy) physical exertion and prolonged strenuous exercise, energy reserves, reduced blood glucose consumption, high body temperature, and affected muscle nerve conduction,Brain dysfunction and a series of physiological changes and symptoms. After taking maltooligosaccharides, it can not only maintain the blood sugar level, reduce the production of blood lactic acid, but also balance insulin. Human experiments have proved that the endurance and functional ability can be increased by more than 30% after using oligosaccharides, with very obvious effects.[1]
The other is called“Bifid factor”OfIsomaltooligosaccharides。These sugars enter the large intestine asBifidobacteriumIt can effectively promote the growth and reproduction of bifidobacteria, the beneficial bacteria in the human body, and inhibit the growth of putrefactive bacteria. Long term consumption can slow down aging, defecate, inhibit bacteria, prevent cancer, fight cancer, reduce the burden on the liver, improve the nutrient absorption rate, especially the absorption of calcium, iron, and zinc ions, improve the lactose digestion and lipid metabolism in dairy products. The higher the content of oligosaccharides,The greater the role of nutrition and health care for human body.[1]
Main properties
Oligosaccharides are composed of monosaccharides, so they have similar physical and chemical properties to monosaccharides, but also have their own personality.[4]
1. Oligosaccharides can form crystals, soluble in water and sweet.[4]
2. They are optically active.[4]
3. Oligosaccharides can be divided into reducing sugar and non reducing sugar according to their different molecular structures.Reducing sugars have the same properties as monosaccharides. For example, if there is spin change in the aqueous solution, they can form glycosides, osazones, and reducing Fehling reagent.Non reducing sugars do not possess these properties.[4]
4. It can be hydrolyzed by acid or enzyme, and the hydrolysate is the monosaccharide composed of the oligosaccharide.Generally speaking, the glycosidic bond bound by two semi acetal hydroxyl groups is most easily hydrolyzed.For example, when raffinose is hydrolyzed with weak acid, fructose and millidisaccharide are produced, and when it is hydrolyzed with strong acid, fructose, glucose and galactose are produced, which shows that the glycosidic bond of sucrose is easier to hydrolyze.[4]
Distribution and intake
Only a few plants in nature contain natural functional oligosaccharides.For example, onion, garlic, mango shell, asparagus, chicory root and artichoke containOligofructose, soybean containsSoybean oligosaccharides。[1]
However, from the perspective of ordinary people's daily dietary habits, it is often difficult for a person to reach the daily recommended amount of oligosaccharides from natural foods every day.Additional oligosaccharides are very beneficial to infants, adults, the elderly, people with high work pressure and those who want to have a healthy digestive system.[1]
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Health function of oligosaccharides
1. Improve the micro ecological environment in the human body, which is conducive to bifidobacteria and otherprobiotics It can produce organic acids through metabolism to reduce the pH value in the intestine, inhibit the growth of salmonella and putrefactive bacteria in the intestine, regulate gastrointestinal function, inhibit intestinal putrefactive substances, change stool properties, prevent constipation, increase vitamin synthesis, and improve human immune function.[1]
2. Oligosaccharides are similar to water solubilityPlant fibre, can improve blood lipid metabolism, reduce cholesterol andtriglycerideContent of.[1]
3. Oligosaccharides are not insulin dependent and will not increase blood sugar. They are suitable for people with high blood sugar and diabetics.[1]
4. Because it is difficult to be affected by salivary enzymes and intestinal digestive enzymeshydrolysis, calorific value is very low, rarely converted into fat.[1]
5. It does not form matrix by caries bacteria, nor has the effect of coagulating bacteria, which can prevent caries.[1]
Therefore, oligosaccharides, as a food ingredient, are widely used in dairy products, lactobacillus drinksBifidobacteriumYogurt, cereal food and health food, especially for infants and the elderly.In the health food series, there are also oral liquids made solely from oligosaccharides, which are directly used to regulateIntestinal flora、Moisten intestines and relieve constipationRegulate blood fat and immunity.[5]
Oligosaccharides are difficult or unable to be digested and absorbed by the human body, and the energy value provided is very low or not at all. This is because the human body does not have the enzyme system to decompose and digest oligosaccharides.Some functional oligosaccharides, such asIsomaltooligosaccharide, fructooligosaccharidesLactulose oligosaccharideA certain degree of sweetness is goodFunctional sweeteners , can play a role in low energy food, such as diet food, diabetes food, hypertension food.[6-7]
Common oligosaccharides
Name Main composition and combination type Main purpose
maltooligosacchatideGlucose (α - 1,4 glycoside bond combination) nourishes nutrition, and has antibacterial properties[8]
IsomaltooligosaccharidesGlucose (α - 1,6 glycoside bond combination) prevents dental caries and promotes the proliferation of bifidobacteria[8]
Cyclodextrin glucose (combined by cyclic α - 1,4 glycoside bond) has low calorific value to prevent cholesterol accumulation[8]
GentianobioseBitter taste of glucose (β - 1,6 glycoside bond) can form packaging connector[8]
Anti caries effect of sucrose coupled with glucose (α - 1,4 glycoside bond)[8]
Fructooligosaccharides (β - 1, 2 glycoside bond binding) Sucrose promotes the proliferation of bifidobacteria[8]
Trehalose glucose (α - 1, 1 glycoside bond combination) fructose anti caries, high-quality sweet taste[8]
Sucrose, oligosaccharide, glucose (α - 1, 6 glycoside bond combination), sucrose, etc. prevent dental caries and promote the proliferation of bifidobacteria[8]
Milk oligosaccharide galactose (β - 1,4 glycoside bond binding) glucose skeleton prevents caries and promotes the proliferation of bifidobacteria[8]
Soybean oligosaccharide galactose (α - 1,6 glycosidic bond binding) sucrose promotes the proliferation of bifidobacteria
Galactooligosaccharide Galactose (β - 1,6 glycoside bond binding) sucrose promotes the proliferation of bifidobacteria[8]
Fructose oligosaccharide galactose (α - 1, 2 ': β - 1', 2 glycosidic bond combination) with high quality and sweet taste[8]
Regulation of water activity of xylooligosaccharide xylose (β - 1,4 glycosidic bond binding)[8]
physiological function
Activating bifidobacteria in the intestinal tract and promoting its growth and reproduction are beneficial bacteria in the human intestinal tract, and the number of bifidobacteria will gradually decrease with age.The number of bifidobacteria in the intestinal tract has become one of the indicators to measure human health.With the rapid development of medical science, broad-spectrum and powerful antibiotics are widely used to treat various diseases, which destroys the normal flora balance in human intestinal tract to varying degrees.Therefore, it is necessary to purposefully increase the number of beneficial bacteria in the intestinal tract.It is simple and reliable to ingest bifidobacteria products, but such products are subject to many restrictions from production to sales. It is more feasible to promote the natural proliferation of bifidobacteria in the intestinal tract by ingesting functional oligosaccharides.[9]
Inhibiting the formation of intestinal putrefaction products in human intestinal tractPutrefactive bacteria(e.gClostridium perfringensandEscherichia coliAnd so on) convert amino acids into putrefaction products such as ammonia and indole.Daily consumption of 10g soybean oligosaccharide powder can significantly reduce the putrefaction products, and can also inhibit the β - glucosidase andAzoreductase。[10]
Oligosaccharides are indigestible sugars, which are not decomposed by gastric acid and stomach enzymes, have a certain sweetness, and basically do not increase blood sugar and lipids after ingestion.Entered into the intestine, it can be used by bifidobacteria in the large intestine, but not by harmful bacteria. It is called bifidofactor and can be widely used in various foods as functional food ingredients[11]。
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There are five main ways to obtain oligosaccharides:[6]
1. Extract from natural raw materials;[6]
2. Synthesis by glycosyl transfer reaction catalyzed by transferases and hydrolases;[6]
3. Enzymatic hydrolysis of natural polysaccharides;[6]
4. Acid hydrolysis of natural polysaccharides;[6]
5. Chemical synthesis;[6]
From the perspective of the food industry, oligosaccharides, as a widely used functional base material, must take into account the production cost. Therefore, it is better to use biotechnology, namely enzymatic hydrolysis or enzymatic transfer, to produce various oligosaccharides.Scientists have basically reached a consensus that the use of enzymes may be the only effective way to synthesize oligosaccharides in large quantities.[6]
Development and application prospects
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Functional food will be the food of the 21st century.Functional oligosaccharide is a kind of excellent functional food base material. China has taken special nutrition products to meet the needs of different people as the development focus of food industry in the 21st century. New oligosaccharides will be an important functional enhancer of these special nutritional foods.More than ten new oligosaccharides have been commercially produced in Japan, Europe and the United States, and are widely used in various functional health products, infant food, and the production, production varieties and application range have increased rapidly.[6]
