1. The document describes a procedure to test the quality of a milk sample using Methylene Blue dye. The procedure involves adding drops of the dye to test tubes containing milk samples and incubating for 15 minutes to observe any color change. 2. A color change within the incubation period indicates the presence of microbes and poor milk quality, while no color change signifies good quality milk. 3. The rate at which the dye color disappears from the test tubes after incubation corresponds to different levels of milk quality, from very bad to excellent.

1. 1
Amjad Khan Afridi 8th
August , 2016
Methylene Blue is an organic compound , in dark green or lustrous crystalline
powder, used in the treatment of methemoglobinema, as a strain
in pathology and bacteriology, and as a diagnostic aid in the detect ion of
premature rupture of fetal membranes.
Objective:
 To check microbial load in the milk sample.
 To check the quality of milk sample.
Requirements:
1. Milk sample
2. Methylene Blue dye
3. Test tubes
4. Test tubes holder
5. Test tubes stand
6. Water bath or incubator
7. Dropper or Pipettes and its tips
8. Swab cotton
9. Aluminum foil
Procedure:
A. Take test tubes and pour 10 ml of milk sample in each test tubes.
B. Then labeled the test tubes.
C. Then add drops ofMethylene Blue Dye in each test tubes.
D. Next incubate the test tubes at 37 C in water bath for 15 minutes.
E. Result: Absorb the color of the test tubes with respect to times.
F. If the color is changed its means that the milk sample having contamination (
Load of Microbes), and the quality of milk is not good, while if there is no
color changed in the test tubes, its means the quality of the concern milk
sample is good.

2. 2
Amjad Khan Afridi 8th
August , 2016
Interpretation:
 If dye color is disappear in 30 minuets , its means that the milk has very
bad ( Poor)quality.
 If dye color is disappear in 1 hour , its means that the milk has bad quality.
 If dye color is disappear in 6 hours , its means that the milk has fair quality.
 If dye color is disappear in 8 hours, its means that the milk has good quality.
 If dye color is disappear in 24 hours, its means that the milk having
excellent quality.
Demonstrated By Madam Sadira 8th
August , 2016
Prepared by Amjad Khan afridi, 7th
semester