Facts about Polysaccharides
Polysaccharides fulfill numerous essential functions in living organisms, and serve important industrial and technological purposes. EPNOE aims to raise awareness about the relevance and potential benefits of polysaccharides in our society.
Polysacchrides are biopolymers made up of somewhere between a dozen to several thousand individual chemically connected sugar molecules. The individual linkage and the molecular structures of these sugars are very diverse and differ from polysaccharide to polysaccharide.
Polysaccharides, such as cellulose and starch, are sustainable and renewable bio-resources.
Researchers are studying new ways to obtain polysaccharides (from agricultural waste, for example) and turn them into functional biomaterials for various applications, ranging from every-day household items to highly functional biomedical devices.
Even though complex polysaccharides are not very digestible, they provide important dietary elements for humans. Called dietary fiber, these carbohydrates enhance digestion, among other benefits.
Glycogen is a multi-branched polysaccharide that shares chemical resemblance to starch.
Animals, fungi, and bacteria use glycogen as a form of energy storage, very much like plants using starch. That is why glycogen is frequently referred to as “animal starch”.
Your Christmas tree consists of approximately 100 septillion chains of cellulose. In theory, from the textile fibers you could get from it, you can make over 50 t-shirts.
Pectin is most commonly known for being a key ingredient that gives jam its jelly-like texture. The molecular structure of this polysaccharide is more complex and diverse than that of DNA, the molecule that stores the genetic code of life.
Cellulose (found in wood), starch (found in flour), and dextran (found in dental plaque) all consist of chemically linked glucose molecules. Yet they greatly differ in their physical, chemical, and biological properties. Their main difference lies in the nature of the chemical bond between these small sugar molecules.
In the brewing process, amylose and amylopectin, two of the major polysaccharides in cereals, are converted to fermentable sugars by natural enzymes.This is the basis for beer-making.
Cellulose, the most abundant organic molecule on Earth, is mostly associated with plants, namely trees.
However, this polysaccharide is also produced by some bacteria and marine animals, such as tunicates.
Bacteria of dental caries use sugar molecules to produce a biofilm of the polysaccharide dextran on the tooth surface. This facilitates bacterial growth, leading to dental plaque formation and ultimately to tooth decay.
Carboxymethyl cellulose is the result of the chemical modification of cellulose.
It is employed as additive in many day-to-day items, such as toothpaste and wallpaper paste. However, it is also essential for the manufacture of pharmaceutical tablets and Li-ion batteries for electric cars.
The first human-made plastic was made of cellulose as raw material. This plastic was not obtained from fossil fuels but from the chemical modification of cellulose: nitrocellulose
This highly flammable compound has been used in film and explosives. Nowadays, nitrocellulose is a key component in most lacquers and in rapid-test strips, including those for pregnancy and COVID-19.
Cotton is a highly pure form of cellulose. However, the increasing demand for human-made fibers in clothing cannot be met by cotton, which is why polysaccharides scientists are continuously working on new ways to turn cellulosic resources into sustainable fibers.
Starch is formed in plants and used as an energy storage.
Native starch is actually a mixture of two polysaccharides that are both composed of glucose molecules: amylose and amylopectin.
The ratio of these two polysaccharides varies according to the botanical origin of the starch.
Cellulose is the major chemical component of cotton fabrics (>90%)
Interestingly, the mechanical strength of crystalline cellulose can be higher than that of most metals and ceramics.
Starch is used in a wide range of applications.
In food industry, it is used in brewing and as thickening agent in baked goods.
In paper industry, it improves the strength and surface properties of paper and paper board.
In textile industry, it is used to reinforce the threads during weaving.
In materials science, it is used as filler in composites.
Cellulose is popular in cosmetics.
It is used as a support material for sheet facial masks, in natural scrubs, and as an additive in personal care formulations.
The glue on the back of postage stamps and on envelopes is formed with water. Interestingly, this would not be possible without the polysaccharide dextrin.
Derived from starch, dextrin is one of the main components of that glue.
Originally extracted from roosters’ comb, hyaluronicacid is commonly known for being an active ingredient in skin care products, and it is often used for medical applications.
This polysaccharide also plays a key role in the wound repair process.
Cellophane, the transparent film used, among other things, for cookie packaging is made of the polysaccharide ‘cellulose’.
But how? The cellulose is dissolved during the so called ‘viscose process’. Then, by pressing the cellulose solution through a thin slit into a regeneration bath, the cellophane film is obtained.
Arabinoxylan is a naturally occurring polysaccharide that can be found in cereals, like rye.
Interestingly, under sour conditions, arabinoxylan molecules form a strong 3D-network that contributes to the volume and stability of sour dough bread.
Paper is a complex material that contains polysaccharides as major components, including cellulose, hemicellulose, and starch.
Cellulose fibers create the paper network, while starch mainly acts as internal and surface sizing agent, and boosts mechanical strength and hydrophobicity.
Xylitol is an artificial sweetener that is often used as a sugar substitute. It obtained through the chemical synthesis of polysaccharides (more precisely the hemicellulose xylan) isolated from wood.
Huge quantities of polysaccharides are produced in nature. However, chemists have developed procedures to synthesize small amounts in the lab too.
These artificial compounds possess very well defined structures, and are used as models: they are employed to study the behaviour of native polysaccharides in their complex environment.
Humans are not capable to digest the polysaccharide cellulose: a major component in grasses and annual plants.
Ruminants like cows, however, possess a combination of bacteria, fungi, and protozoa in their stomach that enables them to degrade the biopolymer into smaller sugar molecules and use it as energy source.
Polysaccharides can be obtained through biotechnological fermentation processes using microorganisms that can build these large biopolymers from small sugar molecules.
One advantage of this approach over a more classical production through forestry and agricultural is that it does not compete directly with food and feed.
Some of our clothes are made of Lyocell. Lyocell, which was originally trademarked as “Tencel”, is a regenerated cellulose fiber made by dissolving pulp in special solvents followed by the so called ”dry-jet-wet spinning”.
Polysaccharide researchers are constantly exploring new ways to make this process more sustainable and affordable.
Chitin is a structural polysaccharide found in the cell walls of some fungi, as well as in the exoskeletons of insects and crustaceans.
Gellan Gum is a food additive that serves various functions such as binding, stabilising, and texturising food products.
It is produced by the bacterium Sphingomonas Elodea through fermentation of sugar.
Cellulose is primarily known for being the major component in wood. However, it is also produced by certain bacteria through the fermentation of glucose. Due to the high water content of the material, bacterial cellulose is of great interest for medical applications, and it is also marketed as a jelly-like food product.
Agar is a substance derived from various species of red algae.
With its natural talent for creating gels, it plays a pivotal role in both food, serving as a plant-based thickener as well as a vegan-friendly alternative to gelatin, and in biotechnology applications, where it nurtures cell cultures and facilitates gel electrophoresis.
Chemically speaking, it’s a blend of two polysaccharides: agaropectin and agarose. The latter is the actual gel-forming component, which makes it a fascinating compound for polymer researchers.
Guar Gum enhances the texture and stability of food products. This polysaccharide is an excellent thickener and stabilizer, and it can prevent the formation of ice crystals, for example in ice cream.