GIFSQ Global Institute for Food Safety & Quality
Login Register

Access the GIFSQ Portal

Select your user type to log in or register a new account.

Student Portal

Access your food safety courses, certifications, and exams.

Login Register

Instructor Portal

Manage courses, view student submissions, and grade quizzes.

Login Register

Company Portal

Manage corporate setup, view employee logs, and access QA services.

Login Register

SOP: Determination of Heat Resistance of Milk by Alcohol Test

GIFSQ — Global Institute for Food Safety & Quality

Scope

This method is applicable to raw milk.

1. Principle

This test is like the COB test regarding the suitability of milk for heat treatment, but it is more sensitive than the COB test. As milk gradually sours and acid is formed, proteins become susceptible to alcohol precipitation. This happens shortly before it loses its stability to pasteurization.

2. Apparatus

  • Test tubes (20 mL capacity)
  • Pipette (2 mL capacity)
Test tubes of milk for the alcohol test
Qualitative test tubes — GIFSQ illustration

3. Chemicals

  • 68% ethanol

4. Procedure

Pipette 2 mL of milk sample into a test tube

↓

Add 2 mL of ethyl alcohol

↓

Mix the contents by shaking gently

↓

Observe carefully at the inner surface of the test tube. The milk is not suitable for heat treatment, or the milk is alcohol test positive, if there is any trace of coagulation, thickening, lumping, flaking, graining, precipitation or dense curd formation

References

Establishment of Regional Reference Centre for Milk Processing and Marketing; Quality Control Manual (Raw Milk and Milk Products): FAO, 2000.