Sampling of Milk
Sampling of milk
Sampling: is the first step in obtaining an accurate chemical analysis of its
constituents and it is extremely important in understanding the results, Samples
must represent the whole mass of milk.
The whole mass of milk as soon as milk is drawn ,the fat globules will begin to
move upward slowly at first ,but as clustering increases ,the speed of upward
motion accelerates, therefore ,It is necessary to redistribute these fat globules
before taking a sample.
Universal Fresh Milk Samples
It is taken each time the collector receives milk at the farm.
The dairy industry should use fresh milk samples for:1. Producer payment
2. Quality control
3. Acceptance of milk
Compost Sample
It is the quantity of milk secured by mixing together proportional parts of
different lots of the product.
e.g. Cow gave
25 pounds of milk in the evening
40 pounds of milk in the morning
Purpose of Sampling
1. Physical analysis
2. Chemical analysis
3. Microbial analysis
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25 ml of milk
40 ml of milk
Compost Sample
Sampling of Milk
Equipments Required for Sampling
1.
2.
3.
4.
5.
6.
7.
Thermometer
Plunger(Milk stirrer)
Dipper
Sterile Syringe(Disposable)
Sampling Containers
Sterile polyethylene Plastic bags (Disposable)
Insulated case or box (Ice box)
Sampling Methods
1. Sample from the pail
The most effective mixing is pouring the milk from one pail to another at
least three time and then immediately withdraw the milk sample.
2. Sample from the Individual animal (directly)
Wash the flank area with warm water
Dry the udder and its teats with disposable paper towels
Sterilize the teats and its orifice with a piece of cotton soaked by 70%
ethanol.
Take milk sample from each quarter separately
3. Sample from the herd(several animals)
Follow the Instructions in point no.1 on each animal then mix all samples
together by plunger for (30 seconds) then take the universal sample.
4. Sample from one can
By well mixing the milk by plunger then take the sample.
5. Sample from several cans
Follow the Instructions in point no.4 on each can then mix all samples
Together then take the universal sample.
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Sampling of Milk
6. Sample from the bulk tank
Cold milk should be agitated for at least 5 minutes prior to sampling.
There are a mechanical agitators in milk collecting trucks (1500 gallons) It is
necessary to provide (20 to 30 )minutes of mechanical agitation to render
the milk homogenous before sampling.
7. Milk bottles sample
No. of milk bottles
No. of samples
1-100
1
101-1000
2
1001-10000
4
<10000
4+1 for every additional 2500
bottles
Precautions that must be taken in sampling bulk tank milk
1. The milk should be well agitated at least 5 minutes.
2. A proper rinsed, sanitized and dried dipper should be used.
3. The dipper should be rinsed with water before placing in the Sanitizing
solution which should be replaced when it appears cloudy.(sod.
hypochlorite)
4. The sampling container should be free of microbial or chemical
contamination.
5. The sampling container should only be 2/3 filled.(to avoid spilling or
churned milk)
6. Never hold glass bottles directly over the milk because of the danger of
breaking or accidental spilling of preserved milk into the milk.
7. Thorough cleaning of the bottles at the end of each sampling and
disinfecting the stoppers with formalin.
8. Samples must be held at temperatures above freezing but below 4C°
until analyzed (Freezing cause destruction of certain microorganisms).
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Sampling of Milk
9. The sample must not be taken from milk that has been frozen or
partially frozen, churned, curdled and lumpy or contamination with
dust, insects and rats.
Identification of samples
The information that should be recorded on the label are:1.
2.
3.
4.
Time and date of Sampling
Source of the milk (cow, goat, camel……)
Name and location of farm
Kind and concentration of the chemical preservative that has been used.
The driver of the tanker must do the following at the farm:1. Smell the milk to detect any spoilage.
2. Check the appearance of the milk ( If it is frozen, churned or any gross
contamination by dust, insect or rats)
3. Record its temperature.
4. Agitate the milk with mechanical agitator.
Churned milk
It is the milk that has been subjected to such a degree of agitation
either during transportation, testing or general handling that has
resulted in the clustering of the milk fat to form butter granules which
are harder in texture than the normal fat.
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