DETECTION OF THE QUALITY OF THE MILK USING MBR TEST

A PRIZE WINNING PROJECT

OMEIAT SCENCE FAIR- 2012 by

I MAX NURSERY & PRIMARY SCHOOLRoyapettah Branch

Chennai

Principle:

The methylene blue reduction test is based on the fact that 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 bacteriaThe 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 Milkb) Sample 2-Ealumalai Milkc) Sample 3-Tirumala Milkd) Sample 4-Appu Milk

Procedure:1 .0 g of methylene blue dye was dissolved in 250ml of

distilled 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

ApparatusThe 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 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 equipmentsApplied for grading the quality of milkMore accurate method

SAMPLES:

Sample 1. Aawin Milk – green 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 colorSample 13. Fresh Milk

Table 1. 

Sl. 

Types of milk 

QuantityMl

 Initial time

Time of color

change

 Duration

 Quality grade.

1. Aavin milk green color

10 3:30 7:00 3hr:30min J

2. Aavin milk orange color

10 11:45 12:45 1hr:00min N

3. Aavin milk blue color

10 11:45 5:25 5hr:40min D

4. Ealumalai milk 10 3:30 8:20 4hr:50min F

5. 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. Raw milk 10 10:04 1:45 3hr:41min I9. Arokya milk 10 10:54 2:49 4hr:45min G

10. Heritage milk 10 10:04 2:07 4hr:3min H11. Dodla diary milk

blue color10 10:04 3:50 5hr:46min B

12. Dodla diary milk black color

10 10:07 1:01 2hr:54min M

13. Fresh milk 10 10:07 1:35 3hr:28min K14. Mother diary milk 10 10:07 1:25 3hr:18min L

Table 2. 

Sl. 

Types of milk 

QuantityMl

 Initial time

Time of color

change

 Duration

 Quality grade.

1. Aavin milkgreen color

10 3:30 7:05 3hr:35min J

2. Aavin milkorange color

10 11:45 12:54 1hr:09min N

3. Aavin milkblue color

10 11:45 5:37 5hr:52min D

4. Ealumalai milk 10 3:30 8:25 4hr:55min F

5. Thirumala milk 10 3:30 9:15 5hr:55min C6. Appu milk 10 3:30 10:10 6hr:40min A

7. Jersy milk 10 11:45 4:52 5hr:07min E8. Raw milk 10 10:04 1:48 3hr:44min I9. Arokya milk 10 10:04 2:56 4hr:52min G

10. Heritage milk 10 10:04 2:10 4hr:6min H11. Dodla diary milk

blue color10 10:04 4:00 3hr:56min B

12. Dodla diary milkblack color

10 10:07 1:07 3hrs:00min M

13. Fresh milk 10 10:07 1:40 3hr:33min K14. Mother diary milk 10 10:07 1:29 3hr:22min L

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