Determine the SNF in Milk by Specific Gravity Method

Principle

The principle involved in measuring the specific gravity by a lactometer is that a floating object sinks until it has displaced a weight of fluid equal to its own weight. The greater is the volume of the displaced fluid, the smaller is the specific gravity of the fluid, and the lower is the lactometer reading.

 Related: Estimation of Fat in Curd by Gerber’s Method

Materials required

1. Lactometer
2. Cylinder
3. Dairy thermometer

  Procedure

1. Mix the sample of milk well. Pour it into a dry cylinder which enables the lactometer to float without touching the sides.
2. Let the lactometer into the cylinder. Take the reading from the lactometer as soon as it becomes stationary.
3. Note the corrected lactometer reading (CLR).

  Calculation

Specific gravity            = 1+ CLR\1000

SNF %( Solids Not Fat) = CLR\4 + 0.2xF + 0.36

Where F = Fat % in the milk sample.

 Result and Interpretation

The lactometer reading taken at 84˚F (29˚C) is the corrected lactometer reading.