Polysaccharides also play important roles in our lives. Starch is the most common type of complex carbohydrate which is present in the food we consume. They are complex carbohydrates formed with a chain of monosaccharides. The bonds that keep the chain together are glycosidic. Some common Polysaccharides examples are starch, glycogen, and cellulose. Polysaccharides can also be defined as the long polymers of carbohydrates that are made up of repeating mono- or di-saccharide units joined by glycosidic connections (e.g., glucose, fructose, galactose). They might be linear or very branching in structure. Storage Polysaccharides like starch and glycogen, as well as structural Polysaccharides like cellulose and chitin, are just a few examples. More than 10 monosaccharide units make up a Polysaccharide. Nonstarch polysaccharides occur naturally in many foods. The physiochemical and biological properties of these compounds correspond to dietary fiber. Ex. Arabinose, Xylose, Mannose, Galactose, Glucose and Uronic acids

1. Polysaccharides
Mrs. R.Subha, M.Sc., M.Phil., D.C.T.,
Assistant Professor of Home Science

2. Introduction
• Polysaccharides also play important roles in our
lives.
• Starch is the most common type of complex
carbohydrate which is present in the food we
consume.
• They are complex carbohydrates formed with a
chain of monosaccharides.
• The bonds that keep the chain together are
glycosidic.
• Some common Polysaccharides examples are
starch, glycogen, and cellulose.

3. • Polysaccharides can also be defined as the
long polymers of carbohydrates that are made
up of repeating mono- or di-saccharide units
joined by glycosidic connections (e.g., glucose,
fructose, galactose).
• They might be linear or very branching in
structure.
• Storage Polysaccharides like starch and
glycogen, as well as structural Polysaccharides
like cellulose and chitin, are just a few
examples.
• More than 10 monosaccharide units make up
a Polysaccharide.

4. Characteristics of Polysaccharides
• They are not sweet in taste.
• Many are insoluble in water.
• They are hydrophobic in nature.
• They do not form crystals on desiccation.
• Can be extracted to form a white powder.
• They are high molecular weight carbohydrates.
• Inside the cells, they are compact and osmotically
inactive.
• They consist of hydrogen, carbon, and oxygen.
• The hydrogen to oxygen ratio being 2:1.

5. Important Polysaccharides

6. 1.Starch
• It occurs in cereal grains, pulses, tubers, fruits etc.
• It is the major source of energy in diet of man.
• Starch is a polymer of glucose.
• Starch is a mixture of two substances, about 25%
amylose (straight-chain polymer) and 75%
amylopectin (branched chain polymer). Because of
the structural differences between amylose and
amylopectin, they exhibit different properties.
• Amylose contributes to gel-formation while
Amylopectin is responsible for thickness properties
of foods containing starch.
• Amylose & Amylopectin chains in granules – semi-
crystalline structure – retards their digestion by
pancreatic amylase

7. Starch classification
• Starch has been classified as
• rapidly digestible starch
• slowly digestible starch
• resistant starch
( depending upon its digestion profile)

8. Rapidly Digestible Starch

9. Slowly Digestible Starch

10. Resistant starch
• Starch and Starch degradation products escapes digestion
in small intestine & available for fermentation by
microflora in large intestine.
• The body cannot easily digest this form of starch, and it
can pass through the digestive system untouched, similar
to dietary fiber.
• It may support healthy intestinal microflora.
RS1 - physically inaccessible starch exists in grains, seeds, and
beans & in processed starchy foods ex. Pasta.
RS2 - Starch that escapes digestion in Small Intestine because of
ungelatinised granules in raw potatoes and unripe bananas
highly resistant to hydrolysis by pancreatic amylase.
RS3 - retrograded amylose formed during cooling of gelatinized
starch (foods that undergo cooking then cooling)such as rice
and cornflakes.
RS4 – produced by modifying the starch to introduce chemical
bonds that leave starch not readily digested - chemically
modified starches is bread.

11. 2. Dextrins
• Degradation products of starch in which
polymers broken down to smaller units by
partial hydrolysis
• Main source of CHO in proprietary preparation
– used as oral supplements for tube feeding.
• Liquid glucose – mixture of dextrins, maltose,
glucose and water – used in products easily
assimilated form to patients who are seriously
ill.
• They are larger molecules than
sucrose/glucose & have less osmotic effect.

12. Nonstarch polysaccharides (NSPs)
• occur naturally in many foods.
• The physiochemical and biological properties
of these compounds correspond to dietary
fiber.
• Ex. Arabinose, Xylose, Mannose, Galactose,
Glucose and Uronic acids

13. Reference
• Srilakshmi B.(2022). Nutrition Science. 7th
Edition. New Age International (P) Ltd.,
• http://ecoursesonline.iasri.res.in/mod/page/vi
ew.php?id=90238
• https://byjus.com/biology/polysaccharides/
• https://www.vedantu.com/chemistry/polysac
charides