Use of Hortvet Apparatus

Hortvet apparatus is used to measure which physical property of milk?

Correct Answer: Freezing point

Hortvet Cryoscope (Hortvet apparatus) is used to measure the freezing point of milk.

Freezing Point of Milk

• Normal freezing point of milk: −0.535°C to −0.550°C (average −0.545°C)
• Cow milk average: −0.547°C; Buffalo milk average: −0.549°C
• Freezing point of pure distilled water: 0°C
• Soluble constituents (mainly lactose and chloride) depress the freezing point below 0°C.
• Addition of 1% water raises the freezing point by 0.006°C — making it the best test for water adulteration in milk.

Instruments and the Properties They Measure

• Quevenne Lactometer (15.6°C): Specific gravity
• Hydrometer / Pycnometer (20°C): Density
• Zeiss Refractometer (20°C): Refractive index (normal: 1.344–1.348)
• Hortvet Cryoscope: Freezing point ✔
• Gerber's Butyrometer: Fat %

Why Other Options Are Wrong

• Refractive index → measured by Zeiss refractometer.
• Specific gravity → measured by Quevenne Lactometer.
• Colour → assessed by organoleptic test, not Hortvet apparatus.