1. Direct Microscopic Count
This test indicates the microbiological quality of raw milk. Measure 0.01 ml milk with the help of a sterile Breeds pipette and spread on a Breeds slide. Dry the smear. Rapid drying results in cracked surfaces on the film or peels off during further processing. Immerse the slide in Newman’s stain for 1 minute. Newman’s stain removes the milk fat, fixes the smear and stains the bacteria in a single operation. The tetrachloroethane of the stain helps to dissolve the milk fat globules, ethyl alcohol fixes the smear and methylene blue stains the smear. Examine under a microscope for the field.
2. Sensory characteristics
This physical test is instant and quick verification of milk from the receiving point. Identifies for foul odour, taste and appearance.
3. Temperature
The higher the temperature, the more bacterial growth. Control and monitor temperature meeting to 45F. Lowering the temperature increases the shelf life of milk.
4. Water
The added water is a top-notch adulteration. Must be tested for water using Lactometer. Normal milk has a density of 1.026 -1.032 g/ml (or 26 – 32 on the lactometer reading). If water has been added, it’s below 26.
5. Chemical Analysis of Nutrients
Total fat, total solids and protein is a must analysed factors in terms of the chemical composition of milk. Electronic equipment in the modern dairy industry facilitates faster and more accurate results. Gerber method to Kjeldhal method is the basic chemical analysis.
6. Sanitation and Hygiene
As coliforms are the indicator organism to ensure the quality of milk and hygiene of the processing area. The absence of coliforms in 1:100 dilutions of raw milk and in 1:10 dilutions of pasteurized milk is accepted as a satisfactory quality.
- Presumptive test
- Confirmatory test
- Most probable number (MPN) for the enumeration of low counts
- Differentiation of Escherichia coli and Enterobacter aerogenes
- Completed test
- Test for faecal coliforms
Author: Meera Jacob
A Food Safety Officer and Food Technologist in nature. Auditing and observing food safety systems is a prior interest. Writing and describing my experience is another passion. The food Industry is a diverse area with food safety as its prime focus to flourish. And that makes me more enthusiastic to work on various Non-Conformances and Risk Analysis. Happy Food Safetying to all Food Safety Professionals !!!
