OMEIAT SCENCE FAIR- 2012
by
I MAX NURSERY & PRIMARY SCHOOL
Royapettah Branch
Chennai
Principle:
 The methylene blue reduction test is based on the fact that
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the color imparted to milk by the addition of a dye such as
methylene blue will disappear more or less quickly.
The removal of the oxygen from milk & the formation of
reducing substances during bacterial metabolism causes
the color to disappear.
Oxygen is consumed by the bacteria
The greater the number of bacteria in milk, the quicker will
the oxygen be consumed, & in turn the sooner will the
color disappear.
Thus the time of reduction is taken as a measure of the
number of organism in milk
Formulation of Hypothesis:
 MBR test shall be used to detect the quality of the
milk.
Materials and Method:
Samples:
 a) Sample 1-Aawin Milk
 b) Sample 2-Ealumalai Milk
 c) Sample 3-Tirumala Milk
 d) Sample 4-Appu Milk
Procedure:
 1 .0 g of methylene blue dye was dissolved in 250ml of distilled
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water.
Four different types of milk packets were selected for the
experiment.
10ml from each type was taken in the test tube.
1 .0 ml of methylene blue dye was added to all the samples. The
color change was noted.
Test tubes were closed with cork.
Samples were kept on a water bath at 37 degree Celsius.
Temperature was maintained using low flame candle.
The color change from pale blue to milky white was noted
down.
Experiment was repeated to get concordant values
Apparatus
 The necessary equipment consists of test tubes with rubber
stoppers, a pipette or dipper graduated to deliver 10 ml of milk
and a water bath for maintaining the samples at 35o to 37oC.
 The bath is protected from light during the incubation period.
 PREPARATION OF METHYLENE BLUE SOLUTION :
 The solution is prepared by boiling 200 ml of distilled water in a
brown stoppered flask and then adding one methylene blue
tablet to the flask of hot water and stirring to dissolve
completely under hot condition.
 The solution may be stored in the stoppered brown flask to
protect from light
Factors Affecting the Test.–
 Many factors affect the methylene blue reduction test
 Cold milk holds more oxygen than warm milk;
 Pouring milk back and forth from one container to another
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increases the amount,
At milking time much oxygen may be absorbed
The kind of organisms affect the rate of reduction.
Light hastens reduction and therefore the tests should be kept
covered.
The concentration of the dye should be uniform as an
increased concentration lengthens the time of reduction.
Increasing the incubation temperature augments the activity of
the bacteria and therefore shortens the reduction time.
Advantages of the Methylene Blue
Test: All apparatus are simple.
 Anybody can do the test
 Large samples are taken, thus eliminating many
sources of error.
 In expensive equipments
 Applied for grading the quality of milk
 More accurate method
SAMPLES:
 Sample 1. Aawin Milk – green
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color
Sample 2. Aawin Milk –
orange color
Sample 3. Aawin Milk – blue
color
Sample 4. Ealumalai Milk
Sample 5. Thirumala Milk
Sample 6. Appu Milk
 Sample 7. Jersy Milk
 Sample 8. Raw Milk
 Sample 9. Arokya Milk
 Sample 10. Heritage Milk
 Sample 11. Dodla diary Milk –
blue color
 Sample 12. Dodla diary Milk –
black color
 Sample 13. Fresh Milk
Table 1.
Quantity
Ml
10
Initial
time
3:30
Time of
color
change
7:00
10
11:45
12:45
1hr:00min
N
10
11:45
5:25
5hr:40min
D
10
3:30
8:20
4hr:50min
F
Thirumala milk
10
3:30
9:15
5hr:45min
C
6.
Appu milk
10
3:30
10:05
6hr:35min
A
7.
Jersy milk
10
11:45
4:43
4hr:58min
E
8.
9.
Raw milk
Arokya milk
10
10
10:04
10:54
1:45
2:49
3hr:41min
4hr:45min
I
G
10.
11.
10
10
10:04
10:04
2:07
3:50
4hr:3min
5hr:46min
H
B
10
10:07
1:01
2hr:54min
M
13.
Heritage milk
Dodla diary milk
blue color
Dodla diary milk
black color
Fresh milk
10
10:07
1:35
3hr:28min
K
14.
Mother diary milk
10
10:07
1:25
3hr:18min
L
Sl.
Types of milk
1.
4.
Aavin milk
green color
Aavin milk
orange color
Aavin milk
blue color
Ealumalai milk
5.
2.
3.
12.
Duration
3hr:30min
Quality
grade.
J
Table 2.
Quantity
Ml
Initial
time
Time of
color
change
10
3:30
7:05
3hr:35min
J
10
11:45
12:54
1hr:09min
N
10
11:45
5:37
5hr:52min
D
4.
Aavin milk
green color
Aavin milk
orange color
Aavin milk
blue color
Ealumalai milk
10
3:30
8:25
4hr:55min
F
5.
6.
Thirumala milk
Appu milk
10
10
3:30
3:30
9:15
10:10
5hr:55min
6hr:40min
C
A
7.
8.
Jersy milk
Raw milk
10
10
11:45
10:04
4:52
1:48
5hr:07min
3hr:44min
E
I
9.
10.
11.
Arokya milk
Heritage milk
Dodla diary milk
blue color
Dodla diary milk
black color
Fresh milk
Mother diary milk
10
10
10
10:04
10:04
10:04
2:56
2:10
4:00
4hr:52min
4hr:6min
3hr:56min
G
H
B
10
10:07
1:07
3hrs:00min
M
10
10
10:07
10:07
1:40
1:29
3hr:33min
3hr:22min
K
L
Sl.
Types of milk
1.
2.
3.
12.
13.
14.
Duration
Quality
grade.
Conclusion:
 According to the experiment made with 14 samples we
find that most of the milks are comparatively worse in
quality. And the quality of APPU brand milk will be
the best in nature.
Pictorial representation of
experiment:
Test tube with milk sample
Water bath to keep the milk samples warm
Milk samples:
Thirumala Milk