This document discusses the analysis of milk and butter. It outlines various tests that can be performed on milk, including tests to determine density, fat content, total dry extract, acidity, and microbiological quality. The preparation of milk samples is also described. For butter analysis, tests are discussed to determine chemical composition, color, acidity, rancidity, and microbial quality over various storage periods. The goal of these analyses is to ensure the quality of both milk and butter products.

1. Analysis of Milk and Butter
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2. contents
Learning outcomes:
• Milk analysis
• Milk analysis process
• Preparation of sample
• Test for milk analysis
• Butter analysis
• Test for butter
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3. Milk Analysis
• To obtain a final well-qualified product, the milk should present some
physiochemical characteristics. The characteristics of the product can be
performed by applying the tests required in the milk analysis.
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4. density
Fat content
Total dry extract Non-fat dry extract
cryoscopy
acidity
Milk Analysis Process:
pH
acidity
TOTAL SOLID CONTENT
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5. Preparation of sample :
Warm the sample to 370 – 400 C by transferring it to
the beaker & keep it in a water bath maintained at
400 – 450C. Stir slowly for proper homogenization.
Mix sample thoroughly by pouring back into the
bottle, mixing to dislodge any residual fat sticking to
the sides and pour it back in the beaker.
Allow the sample to come to room temperature (260
- 280 C) and withdraw immediately for analysis.
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6. Test of microbiological milk analysis:
• Standard plate count
• Deduction of cane sugar
• Somatic cell count
• Methylene blue reduction test
• Resazurin test
• Lovibond comparator
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7. Detection of Cane Sugar in Milk:
• PRINCIPLE:
• Fructose + resorcinol in HCl Red color
Procedure:
 Add milk + conc. HCl and wait for 10min ppts will
formed
 Filter the mixture and take 1 ml of milk serum & 5
ml modified resorcinol - HCl reagent
 Placed in water bath for 1min
 Withdraw the tube &observe the red colour
 Cane sugar dedected.
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8. Methylene blue Reduction test
• Methylene Blue is blue coloured dye.
• Aerobic bacteria are common contaminates of
milk.Such bacteria release respiratory burst
metabolites as a result of active metabolism.
• These metabolites reduce the methylene blue
that intimately turns in white colour.
• Rate of reduction of methylene Blue is directly
related to with bacterial load in milk.
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9. Test procedure:
• Add 10ml of milk in a test tube.
• Then add 1ml of methylene blue in a test tube containing
milk.
• Invert the test tubes for about 4-5 times so that
methylene blue mixes with the milk evenly.
• Then place the test tube in a water bath at 37 C
• Now keep a note of the incubation time as it is the time
taken for the colour to turn into white colour.
• Now steady the tube for about 5 mints.
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10. Result of Reduction Test:
Result
Colour disappear within 30 mints Very poor quality of milk
Colour disappear between 30 mints
to 2 hrs
Poor quality of milk
Colour disappear with 2 hrs-6hrs Fair quality of milk
Colour disappear within 6hrs-8hrs Good quality of milk
No reduction of colour within 8hrs Excellent quality of milk
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11. Resazurin test :
• The Resazurin test is designed for assessing
the quality of raw bulked milk.
• Resazurin gives milk a characteristic blue
colour and the test is based on the ability of
bacteria in the milk to reduce the blue dye.
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12. Procedure of the test:
• Take 2 test tube and add 10ml of milk in both the
test tube and labeled it as A and B.
• At one test tube such as A, we will add resazurin
solution and close the test tube gentely with
stopper allow milk to thoroughly mix in the dye.
• At another test tube B we will not add dye, it’s
called blank test tube.
• Then place both the test tube in a Lovibond
comparator with Resazurin disk and compare it
colourimetrically.
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13. Result of Resazurin test
Resazurin Disc
Number
Colour Milk grade Action
06 Blue Excellent Accept
05 Purple Good Accept
04 Pink Bad Reject
03 white Very bad reject
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14. Total dry extract (TDE
• The dry extract may be defined as “all components of milk
except water”.
• They determine the nutritional quality and industrial yield of
the milk products.
• Material:
• Ackermann’s disk
• The Ackermann’s disk is the indirect ,low cost, and more
practical method to determine the total dry extract(TDE)
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15. Non-fat dry extract (NFDE)
• The non-fat dry extract may be defined as being “all
components of the milk ,except water and fat”.
• Its measure is important for verification of the water content
in the milk . It is more convenient than the total dry extract
because the fat can widely vary , therefore making the
comparison a difficult one.
• Determination methods
• The non-fat dry extract is determined , by subtracting the
content of fat from the
• Total dry extract : NFDE= TDE-fat
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16. DETERMINATION OF pH:
• pH Meter Calibrate the Avg pH 6.6 in milk due to
lactic acid
• Determination of total solid:
Take a weight of crucible.
Weigh 5 g of milk in a crucible put a crucible in a water
bath until dryness.
After complete dryness put the crucible in an oven,
and weigh after cooling.
determination the percent of total solid.
%Of total solid = (wt of crucible +sample) after drying – wt
of crucible/ wt of sample * 100
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17. Acidity
• The acidity determination is a
fundamentally important test for the
industry because it indicates the
convenience or inconvenience of using the
milk . The acidity of the milk can be
determined by the ‘Alizarol test.’
• Material and reagents
 Salut acidimeter
 76% Alizarol solution
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18. Method of determining acidity
 Mix 2ml of the milk to be analyzed with
2ml of the alizarol solution.
 Observe both the coloration and texture of
the mixture
 The acid milk presents a mixture where the
coloration of the alizarol is rosy (little acid)
or yellow (very acid), besides presenting
clots;
 The normal milk presents a mixture with a
brick-red coloration and clothes;
 The alkalinized milk(usually by increment of
water or neutralizing substances) presents
violet coloration.
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19. Butter
• Butter is dairy product made by churning
cream or milk to separate butter fat from
milk.
• Butter is typically light yellow and has a
variety of uses such as spread on bread
products
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20. Butter analysis
 Chemical Analysis of butter.
 Colour analysis of butter.
 Determination of titarateable acidity.
 Rancidity
 Organoleptic test
 Sediment test
 MBR test
 Total bacterial count
 Yeast and Mold count
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21. Chemical analysis of butter
• Total solids content of butter samples
was measured by recording the weight
lost from samples after drying in an
oven at 102°C for at least 15 h.
• Fat content of cream and butter
samples was analyzed by the Röse–
Gottlieb method (International Dairy
Federation, 1996)
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22. Colour analysis of butter
• Color measurements were taken from the surface
of newly opened cups of butter following;
1 week, 1 month, 3 month and 6 month
storage at 5C
• Five replications of
(lightness)
(red-green color), and (yellow-blue color) values
were taken at random locations across the surface
of the butters using a Minolta Chroma meter.
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23. Determination of titarateable acidity
Principle:
The butter is melted in hot water and the hot solution
is titrated with standard alkali till neutral to
phenolphthalein
Procedure:
• Weigh accurately about 20 g of the butter sample in a
dry 250-ml conical flask.
• Add 90 ml of hot, previously boiled water and shake
the contents.
• While still hot, titrate with 0·02 N sodium hydroxide,
using one millilitre of the phenolphthalein as an
indicator.
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24. Rancidity:
• Butter gets rancid due to microbial, enzymatic or chemical
degradation of fat constituents. The fat hydrolysis in butter
mainly due to the activity of microbial lipases.
SENSORY ANALYSIS:
A sour-bitter taste is identifiable with rancidity (i.e.
blue cheese). Rancid butter becomes yellow to brown
and the flavor becomes harsh:
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