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August 2013 - October 2013, Vol. 3, No. 4; 2623-2627.
E- ISSN: 2249 –1929
Journal of Chemical, Biological and Physical Sciences
An International Peer Review E-3 Journal of Sciences
Available online atwww.jcbsc.org
Section B: Biological Science
CODEN (USA): JCBPAT Research article
Estimation of the Type and Quantity of Sugar in Milk
Ajit V Pandya, Dhigesh Joshi, Sheban Vora and Ajay Vishwakarma
Department of Biochemistry, C.U.Shah Science College,
Ahmadabad Gujarat, India
Received: 18 July 2013; Revised: 14 August 2013; Accepted: 20 August 2013
Abstract: Sugar/Carbohydrate is widely present in all the living substances hence it is
called the “staff of life”. It is present as a storage form in all the fruits, vegetables in its
various forms and quantities. It was determined through a series of experiments
performed on a selected sample of cow milk as the research material and the results
revealed that it contained mainly one sugar: Lactose. The lactose gives milk its sweet
taste and contributes approximately 40% of whole cow's milk's calories. Lactose is a
disaccharide composite of two simple sugars, glucose and galactose. The quantity of
sugar was estimated to the value of 4.7 gm in 100gm of milk. The values obtained are
within the range. Milk contains Lactose, Casein protein, fat and fat soluble vitamins.
Under certain conditions, the sugar content of the milk may vary such as degree of
freshness and contamination of milk, type of animal from which the milk is obtained,
time of milching the cow or any other animal and the methods used during milching It is
recommended to consume milk regularly and in large quantities in order to fulfill the
nutritional requirements of the body.
Keywords: Carbohydrates, Milk, Lactose, Folin-Wu method, Homogenate.
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INTRODUCTION
Sugar is the generalized name for a class of sweet-flavored substances used as food. They
are carbohydrates and are composed of carbon, hydrogen and oxygen. There are various types of sugar
derived from different sources. Simple sugars are called monosaccharides and include glucose, fructose
and galactose. The table sugar most customarily used as food is sucrose, a disaccharide. Other
disaccharides include maltose and lactose. Sugars are found in the tissues of most plants. The average
person consumes about 24 kilograms of sugar each year equivalent to over 260 food calories per person,
per day1. Sugar has been linked to obesity and suspected of being implicated in diabetes, cardiovascular
disease, dementia, muscular degeneration and tooth decay. Through photosynthesis plants produce
glucose, which has the formula C6H12O6, and convert it for storage in the form of fruits and vegetables as
an energy reserve in the form of other carbohydrates such as starch, or sucrose.
Types of Sugar: Monosaccharides: Glucose, fructose and galactose are all simple sugars,
monosaccharide’s, with the general formula C6H12O6. Disaccharides: Sucrose, maltose and lactose are all
compound sugars, disaccharides, with the general formula C12H22O11. They are formed by the
combination of two monosaccharide molecules with the exclusion of a molecule of water.
Polysaccharides: Polysaccharides are long carbohydrate molecules of repeated monomer units joined
together by glycosidic bonds. Polysaccharides have a general formula of Cx (H2O) y. Examples include
storage polysaccharides such as starch and glycogen, and structural polysaccharides such
as cellulose and chitin. The body uses carbohydrates directly from the monosaccharide glucose. Glucose
is in the blood and extracellular fluids (lymph) and can be made from glycogen. Glycogen is stored in the
liver and muscles of the body. Energy is derived from glucose by the splitting of the glucose molecules
into smaller compounds and oxidizing these to form water, which frees quite a large amount of energy.
Nerve cells are very dependent upon glucose for their function.
The glycogen in nervous tissues remains constant and is not mobilized for conversion to glucose. When
insufficient carbohydrates are consumed to meet the energy needs of the central nervous system, besides
the occurrence of gluconeogenesis, another phenomenon occurs during a fast of three weeks or more.
Carbohydrates provide the major fuel for muscular exercise. Fats and proteins can be used only indirectly
by first being converted into carbohydrates. For this reason, a proper diet should consist primarily of
carbohydrates not primarily of proteins and fats as are commonly consumed in conventional nonvegetarian diets. Cellulose is known to be indigestible by humans, though it is digested and used for
energy by herbivores.
The claims made about "the beneficial role of dietary fiber in preventing diseases" are so popular and so
widely made that they are practically accepted as fact. However, cellulose, though in fact a carbohydrate
because it is utilized as such by herbivores, does not serve the role of a carbohydrate in human
physiology. Because it cannot be digested and utilized by humans, it cannot provide us with energy but
forms roughage which is vital for the body. Milk is a white liquid produced by the mammary glands of
mammals. It is the primary source of nutrition for young mammals before they are able to digest other
types of food. Early-lactation milk contains colostrums, which carries the mother's antibodies to the baby
and can reduce the risk of many diseases in the baby.
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Ajit Pandya et.al.
It also contains many other nutrients2.As an agricultural product, milk is extracted from mammals and
used as food for humans, worldwide dairy farms produced3 about 730 million tones of milk in 2011.
India is the world's largest producer and consumer of milk, yet neither exports nor imports milk. New
Zealand, the European Union's 27 member states, Australia, and the United States are the world's largest
exporters of milk and milk products.
China and Russia are the world's largest importers of milk and milk products1. Cow's milk has been
processed into dairy products such as cream, butter, yogurt, ice cream, and especially the more durable
and easily transportable product, cheese. Modern industrial processes produce casein, whey protein,
lactose, condensed milk, powdered milk, and many other food-additive and industrial products. Humans
are an exception in the natural world for consuming milk past infancy, despite the fact that most adult
humans show some degree of lactose intolerance4. Milk can be consumed in various forms such as
skimmed milk, whole milk, fat free milk, organic milk, lactose free milk etc. The recommended daily
intake for children and teenagers is given below:
Age
Milk
1
2–3
4–8
9–13
14–18
Year
Years
Years
Years
Years
2 cups
2 cups
2 cups
3 cups
3 cups
Milk should also be consumed by adults mainly women as it would cut the risk of many bone related
diseases.
MATERIALS AND METHODS
Sample Collection: The Milk used for the research work was whole milk of collected from a cow at a
local stable in Gandhinagar and was stored at low temperature. The experiment was performed on 6th of
December 2012. All reagents and standards used in this work for various determinations were of
analytical grade. The methods used in this work are the standard methods.
Preparation of Homogenate: The milk needed for the estimation of type and quantity of sugar should be
protein and fat free. In order to use a pure carbohydrate containing sample 23ml of HCl was added to 70
ml of sample of milk. HCl deproteinizes the milk and all the protein coagulated and settled in the bottom
of the flask. The supernatant was separated. Its quantity was found out to be 23ml. It was further diluted
with 77 ml milk to make the volume up to 100 ml. Two types of tests were performed on the homogenate
in order to determine the type and the quantity of the sugar present in milk differently.
Estimation of type of Carbohydrate: To find out the types of carbohydrate present in any sample a
series of tests are performed on it. These include:
Estimation of Sugar by Folin-Wu method: Principle: The sample is heated with alkaline copper
solution by using a special type of Folin-Wu tubes. Glucose (and other reducing substances) reduces
copper from the cupric ions to the cuprous ions. When phosphomolybdic acid is added it is reduced from
cuprous form to blue coloured molybdenum blue. Intensity of molybdenum blue is directly proportional
to sugar. Its concentration is measured colourimetrically with a known standard at 420 nm.
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RESULT AND DISCUSSION
The type and quantity of sugar was estimated from Milk. The results revealed that Lactose is present in
the milk (Table 1) and the sugar content in it is 4.7 gm per 100gm. Variations may occur in the quantity
of Sugar because of the time interval between the experiments performed. Oxidation caused during the
preparation of homogenate also destroys some sugar. Dilution of the sample also leads to the deterioration
of the quantity of sugar. Milk should be consumed regularly as it is a wholesome food. Besides
carbohydrates it is full of essential vitamins, proteins and fats. It is essential for the proper growth and
maintenance of the body
Table-1: Methods of testing Sugar.
TEST
Test for carbohydrate:
Molisch’s Test
Test for polysaccharide:
Iodine Test
Test for Reducing Sugar:
Benedict’s Test
Fehling’s Test
Picric acid Test
Test for Ketose Sugar:
Seliwanoff’s Test
Phosphoric acid Test
Cobaltous chloride Test
Test for Monosaccharide:
Barfoed’s Test
Test for Osazone:
Phenyl Hydrazine Test
OBSERVATION
Purple ring obtained
INFERENCE
Therefore, Carbohydrate is present
No purple colour obtained
Therefore, Polysaccharide is absent
Red-green ppt obtained
Red ppt obtained
Reddish brown colour obtained
Therefore, Reducing sugars such as
Glucose,
Fructose,
Galactose,
Maltose or Lactose may be present.
Cherry red colour not obtained
Brown coloured ring not obtained
Purple coloured ring not obtained
Therefore, ketose sugar such as
Fructose or Sucrose is absent.
Red button not obtained in the
bottom of the test tube
Woolen Ball shaped osazone
obtained.
Monosaccharide such as Glucose,
Fructose or Galactose are absent
Lactose is confirmed.
Result: From the above tests it was confirmed that Lactose is present in Milk. CONCLUSION
It is thus concluded from the above experiments that Lactose is present in the milk and the sugar content
in it is 4.7gm per 100gm. The destruction of sugar occurs on long exposure of the milk at room
temperature.
RECOMMENDATION
It is suggested that milk used should be fresh and it should be boiled before usage in order to kill all the
pathogenic microorganisms and it should be consumed regularly in order to maintain proper health.
Further research should be performed in order to check whether time is a main factor for the proper
quantity for sugar.
ACKNOWLEDGEMENT
We are thankful to research students and all the staff members, the head of department and Principal Mam
of C.U Shah Science College for allowing us to perform this research work in the laboratory.
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REFERENCES
1. "Food Outlook – Milk and Milk Products". FAO, United Nations. 2010
2. Pehrsson et al . "USDA’s National Food and Nutrient Analysis Program: Food Sampling".
Journal of food composition and analysis, 2000, 13: 379–389. doi:10.1006/jfca.1999.0867,
3. "Food Outlook – Global Market Analysis". Food and Agriculture Organization of the United
Nations. May 2012. pp. 8, 51–54.
4. Champe, Pamela (2008). "Introduction to Carbohydrates". Lippincott's Illustrated Reviews:
Biochemistry, 4th ed. Baltimore: Lippincott Williams & Wilkins. p. 88. ISBN 978-0-7817-69600.
Corresponding author: Dr. Ajit V Pandya; Department of Biochemistry,
C.U.Shah Science College, Ahmedabad Gujarat, India
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