Milk Quality Test.pptx

Milk Quality Test

1. DEPARTMENT OF MICROBIOLOGY VIVEKANANDHA ARTS AND SCIENCE COLLEGE FOR WOMEN SANKARI,SALEM SUBJECT : FOOD MICROBIOLOGY Submitted by Nandhini Sekar III-B.SC Microbiology Department of microbiology Vivekanandha arts and science college for women Sankari Salem. Tamilnadu, India. MILK QUALITY TEST

2. CONTENT : INTRODUCTION MILK CAN BE TESTED FOR : MBRT TEST RESAZURIN TEST LITMUS TEST

3. INTRODUCTION : Milk quality is the most important factor in dairy production. It affects milk’s nutritional value, taste, and safety. As such, milk quality control tests are important to ensure quality and safety. But quality control in the dairy industry is a relatively complex process that requires a lot of time and resources.

4. Milk testing and quality control should be carried out at all stages of the dairy chain. Milk can be tested for: Quantity – measured in volume or weight; Organoleptic characteristics – appearance, taste and smell; Compositional characteristics – especially fat, solid and protein contents; Physical and chemical characteristics; Hygienic characteristics – hygienic conditions, cleanliness and quality; Adulteration – with water, preservatives, added solids, etc; Drug residues.

5. COMMON MILK GRADING TECHNIQUES MBRT TEST RESAZURIN TEST LITMUS TEST

6. Methylene Blue Dye Reduction Test, commonly known as MBRT test is used as a quick method to assess the microbiological quality of raw and pasteurized milk. This test is based on the fact that the blue colour of the dye solution added to the milk get decolourized when the oxygen present in the milk get exhausted due to microbial activity. The sooner the decolourization, more inferior is the bacteriological quality of milk assumed to be. MBRT TEST

7. PROCEDURE The test has to be done under sterile conditions. Take 10 ml milk sample in sterile MBRT test tube. Add 1 ml MBRT dye solution Stopper the tubes with sterilized rubber stopper and carefully place them in a test tube stand dipped in a serological water bath maintained at 37±1⁰C. Record this time as the beginning of the incubation period. Decolorization is considered complete when only a faint blue ring (about 5mm) persists at the top.

8. RESAZURIN TEST Resazurin is a kind of test that is done to check the quality of the milk and its consistency. The milk that is contained in a bulk has been tested through this test because it is not possible for the test if the quantity of the milk is less. Through this test, the milk has been given a bluish color to its character. Initially, the test is based on the bacteria that are present in the milk It is a rapid test of three hours that suggests the milk whether is all good or bad for us. The resazurin test gives the bluish characteristic color to the milk that is all based on the quality of the milk. The milk quality is considered by only noting the color change degree of the milk.

9. PROCEDURE : Mix the Milk sample thoroughly by inverting from one to another container. Take 10 ml of milk into a test tube and add 1 ml of working solution of Resazurin solution. Put air tight closure to prevent oxygen entry.Invert the test tubes to mix the milk and Resazurin solution. Place the test tubes in a thermostatically maintained water bath at 37.5 °C for 10 minutes.Immediately match the colour of the milk with the Lovibond colour standards for Resazurin discs.

10. LITMUS TEST : Litmus milk is an undefined milk-based medium consisting of skim milk and the pH indicator azolitmin Litmus milk medium differentiates microorganisms based on their ability to metabolize litmus milk. Four essential reactions in litmus milk are; lactose fermentation, reduction of litmus, casein coagulation, and casein hydrolysis. It is especially useful in the species differentiation within the genus Clostridium. Litmus Milk is a differential medium used to determine different metabolicfunctions. Litmus Milk is also useful in the maintenance and propagation of lactic acid bacteria

11. PROCEDURE 1. Inoculate with 4 drops of a 24-hour broth culture. 2. Incubate at 35°-37°C in ambient air. 3. Observe daily for seven days for alkaline reaction (litmus turns blue), indicator reduction, acid clot, acid reaction (litmus turns pink), rennet clot, and peptonization. 4. Record all changes.

12. THE APPEARANCE OF LITMUS INDICATOR

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