Dr. Seema Huda
Sugar is not only a essential household commodity and sweetener but
it is also a major source of carbohydrates for human body. Sugar is a
major element in confectionary and in desserts. Cooks use it as a food
preservative as well as for sweetening. The crystallized sugar is not
only good in appearance and taste but it consists many properties
also. The main purpose of this paper is to elaborate these Physical,
Chemical and Biological (PCB) properties. The paper has been
Methodology, Chemistry of sugar, Properties of sugar and
Limitations followed by Conclusion.
Key Words– Physical, Chemical, Biological (PCB), Carbon(C), Carbon dioxide (CO2),
Hydrogen (H), Oxygen (O), Molecules.
Human bodies can be thought of as Chemical processing plants. Firstly,
chemicals are taken in, processed with in body through various types of reactions, and
then distributed throughout the body for immediately use or stored for later use. It can be
categories as: (I)Macronutrients- we take it in diet regularly but in large quantities as
carbohydrates, fats and proteins. (II)Micronutrients- that we need only in small amounts
as calcium, iron, potassium, sodium, zinc etc.
Carbohydrates for human body can be obtained directly from sugar as energy
source. Only plants can make sugar and other animals and human beings eating foods
Assistant Professor in Economics, University College, Department of Economics, Kurukshetra
University, Kurukshetra; M- 09468319527, 09416130555, E-Mail- [email protected]
that contain them such as rice, breads, potatoes etc. It gives them energy. Animals and
human break down carbohydrates during the process of metabolism (energy releasing
process in the body) and gain energy. The chemical metabolism of the sugar glucose is
C6H12O6 + 6O2  6CO2 + 6H2O + energy
Human beings eat plants and then they release Carbon dioxide (CO2), Hydrogen (H2O)
and energy in metabolic process.
1. To elaborate chemistry of sugar in brief.
2. To explain physical, chemical and biological properties of sugar in a simple way
with appropriate scientific examples.
The present study has made use of secondary data to elaborate the inherent properties of
sucrose, commonly known as sugar.
Sugar/Sucrose (scientifically), belongs to one of the families of sugars known as
saccharine in the grouping called carbohydrates. Chemically sugar and carbohydrates are
synonyms, but sugar refers to sweet, small, soluble carbohydrate and is used as a
synonym for saccharose (sucrose). Its scientific name is ‘Saccharum Officinarum’.
Monosaccharides called ‘simple sugars’ as glucose which stores chemical energy that
biological cells convert to other type of energy. Glucose is also found in human blood
plasma having the molecular formula C6H12O6. While disaccharide, a crystalline solid,
known as ‘table sugar’ or ‘saccharose’. Common sugar (sucrose) is made from sugar
beets or sugar cane, edible crystalline substances including sucrose, lactose and fructose.
Biochemists regard sugars as relatively simple carbohydrates. Sugars include
monosaccharides, disaccharides, trisaccharides and the oligosaccharides– containing 1, 2,
3 and 4 or more monosaccharide units respectively.
The saccharine is a large family with general formula CnH2nOn. The simplest of
the sugars is glucose C6H12O6, although its physical chemistry is not that simple because
it occurs in two distinct forms, the sucrose molecule is compound of twelve atoms of
carbon, twenty two atoms of hydrogen, and eleven atoms of oxygen. As
Sucrose (C12H22O11) is a condensation molecule made up of two molecules that are
glucose (primary form of sugar stored in human body for energy) and fructose (sugar
found in fruits) and both have same chemical formulae C6H12O6. Plants form it only. The
process whereby plants make sugar is Photosynthesis. The plant takes in CO2 from the
air through pores in its leaves and absorbs water through its roots. These are combined to
make sugar. They use energy from the sun and with the help of a substance called
Chlorophyll, which is green and allows it to absorb the sun’s energy more readily, and
which, gives the plants leaves their green color. The reaction of photosynthesis is
12CO2 + 11H2O  C12H22O11 + 12O2
Carbon dioxide + Water  Sucrose + Oxygen
Hence, oxygen is given off during the process of photosynthesis, and sucrose that is a
disaccharide of glucose (left) and fructose (right) that is important molecules in the body
(Glucose (12) fructose)
Figure 1. Chemical Structure of Sucrose Molecule
Since sucrose consists of glucose unit bonded to a fructose unit. When it melted it will
decompose into glucose and fructose. AsC12H22O11 + H2O  C6H12O6 + C6H12O6
Sucrose + Water  Glucose + Fructose
The chemical metabolism of the sugar glucose is
6CO2 + 6H2O + energy (sunlight)  C6H12O6 + 6O2
Physical Properties of SugarIn appearance sucrose/sugar is solid and colorless, odorless, sweet tasting. It has
following physical properties:
Sucrose is extremely soluble in water and in alcohol and other polar solvents
while insoluble in benzene, ether and other non-polar organic solvents. Generally,
at the freezing point of water 180 grams of sucrose are soluble in 100 grams of
water and 500 grams at its boiling point. While about 138 grams sugar are soluble
in 100 grams of alcohol (ethanol) at room temperature.
Sucrose is non-conductor. A pure solution of sucrose will have no conductivity as
measured against a water standard and it also reduce the conductivity of salt
Sucrose and Water Humidity
Sucrose can ‘tie up’ water. It affects the water activity (a w) of the solution in
which sucrose is present. As
a w = P / Po
P= Partial vapor pressure of food moisture
Po= Saturation vapor pressure of water
Water activity is sometimes referred to Equilibrium Relative Humidity (ERH).
Water is a solution of 44o Brix Sucrose (56% moisture) has the same water
activity, 0.8, as a mixture of starch and water with a moisture of 20 per cent.
Thus, we use sucrose as in the preservation of foods.
Impact on Vapor Pressure
The vapor pressure of water in an aqueous (watery) sucrose solution will
decrease with an increase in dissolved sucrose.
Impact on Surface Tension
Adding sucrose in solution increases its surface tension (highly strung state) of
the solution.
Effect on Boiling and Freezing Points
Sugar in solution lowering the freezing point and raising the boiling point of that
solution in which it added.
Heat of Solution Decreases
When crystalline sucrose is dissolved in water, the temperature of that solution
decreases. While for amorphous (shapeless) or milled (moderate) sucrose, the
heat of solution is positive. A decrease in temperature is also observed on
diluting/adding more water into solution.
Viscosity is the resistance (hindrance) to flow and fluidity is its reciprocal. In
sucrose solution, viscosity increases with more solids content but not linearly.
While viscosity decreases rapidly with an increase in temperature of that solution.
In general term, as sucrose purity decreases its viscosity will increase.
Chemical Properties of SugarAll sugars are fairly reactive. Hence, glucose and fructose molecules are bonded
together when the sucrose molecule is formed. These two monosaccharides are
much more reactive than sucrose. Hence, they act as chemical reducing agents.
Chemical properties of sugar are:
Inversion Reaction
In acidic solutions, sucrose will break down into its two components
monosaccharides (glucose and fructose). This reaction will accelerate acidity and
increase temperature. Most sucrose reaction in solutions, including human
metabolism (energy releasing process in body) begin with inversion reaction.
Thermal Decomposition
While crystalline sucrose is dry, it will be stable up to its melting point but when
it melted, it will decompose into glucose and fructose. If it is heated to around
200oC, a whole series of decomposition products are formed. Then a non-sweet,
dark brown, water-soluble mixture called ‘Caramel’ is produced. Further heating
will lead to a Carbon residue (ash) and in the presence of oxygen; this thermal
decomposition becomes combustion (burning), forming CO2 and H2O.
Acidic Degradation
In acids, having pH (Hydrogen in concentration) below 3, the resulting
monosaccharides from the inversion reaction will form various condensation
(release of water) reaction products. This will result into making a series of
oligosaccharides, in which many monosaccharides are jointed, as isomaltose, just
like disaccharides, and gentiobiosse along with furan-type derivatives.
Alkaline Degradation
The alkaline degradation products of sucrose are more likely to include cleavage
(splitting process) products as organic acids. Once the process starts, the primary
products released participate in further reactions as formation of cyclic
compounds (Ketose and Acids).
Non-reducing and Stability of Sucrose
Sucrose is a non-reducing and stable in heated, up to 1000 C. Its molecule
fructose will decompose above 600 C and both glucose and fructose are unstable
in alkaline solutions, while sucrose remains most stable.
3. Biological Properties of SugarSugar is an important feed stock for many critical biological reactions. Biological
properties are:
Yeast Fermentation
Sucrose/sugar used in yeast fermentation process. Sugar has been used in bread
causing to be rise and converting grapes juice into wine. It produces alcohol and
CO2 . In baking, sugar added to converted into volatile (flying) compounds that
are given off as gas and vapors in the oven. In alcoholic beverage production, in
wine making converts the 18 to 24 per cent sucrose content of the pressed grapes
juice into 10 to 13 per cent alcohol by volume. Sweet and dessert wines are made
by adding additional sugar to the fermenting mixture.
Lactic acid (found in curd), Citric acid (found in lemon), Butyric acid, Acetic
acid, Ketose and many other chemicals are commercially produced by
biochemical means with sucrose used as a substrate or starting material.
1. Physical, Chemical and Biological properties of sugar are discussed in brief
without more scientific complex explanations.
2. Only ring structure of sugar is composed and the linear structure of glucose and
fructose remained untouched.
3. Only Disaccharide has been discussed.
After discussing the Physical, Chemical and Biological properties of sugar we
conclude that sugar has the properties of solubility, non-conductivity, effecting vapor
press and surface tension, affecting boiling and freezing points of water. Along with
this sugar has the feature of non-reducement and stability, thermal decomposition
and acidic degradation. It helps in yeast fermentation and as a preserver and starting
material in biochemical. After decomposing into glucose and fructose it can be again
combined into sucrose. Hence, sugar has so many properties and necessary for
human body for energy as a carbohydrate that shows the importance of sugar.
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3. Article on "Sugar Chemistry", Wageningen University, Nether land
4. Carpi Anthony (2003), “Carbohydrates”, Visionlearning, Vol. CHE-2(5)
5. Francl Michelle M., Lecture delivered by Professor on “Turning Sugar Inside
Out”, at ‘Bryn Mawr College’, December 2013
6. Nelson David L. and Cox Michael M. (2005), “Principles of Biochemistry”
Published by W. H. Freeman and Company, New York.
7. Pennington Neil L. and Bake Charles W. (1991), “Sugar- A User’s Guide to
Sucrose”, Van Nostrand Reinhold Press, New York
8. Voet Donald, Voet Judith G., Pratt Charlotte W. (1999), "Fundamentals of
Biochemistry", Published at John Willey & Sons, Inc., L –14.
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