"The lacteal secretion, practically free from colostrums, obtained by the complete
milking of one or more healthy cows, which contains not less than 3.25% of milk-fat
and not less than 8.25% milk-solids-not-fat.”
1.2 Milk Products:
“A dairy product is food produced from the milk of mammals. Dairy products are
usually high energy-yielding food products. A production plant for the processing of
milk is called a dairy or a dairy factory.”
1.3 Milk by-Products:
“A dairy by-product may be defined as a product of commercial value produced during
the manufacture of a main product. The newly acquired economic importance of a
by-product will make it a main product in the future”
1.4 Ranking Wise Milk Production:
7. Russian Federation
9. New Zealand
*WORLD: 721.4 Million Ton ECM
137.5 Million Ton ECM
84.3 Million Ton ECM
41.6 Million Ton ECM (2nd buffalo milk producing)
33.9 Million Ton ECM
32.0 Million Ton ECM
31.1 Million Ton ECM
30.1 Million Ton ECM
25.2 Million Ton ECM
21.3 Million Ton ECM
14.1 Million Ton ECM
**ECM (Energy Correct Milk)
Ref: IFCN 2012 dairy report
1.5 Composition of Milk:
Unit.2: Value Addition in Milk
2.1 VALUE ADDITION TO MILK:
Dairy farmers have the opportunity to add value to raw milk by producing a wide
variety of processed products, to increase the return above the base price of raw milk.
Heat-treated liquid drinking milk, such as pasteurizing, or ultra high treatment,
then adding flavors or incorporating it into other drinks
Separating the milk fat from other milk solids to produce butter and ghee, and
also skim milk
Fermenting milk to produce yoghurt, which is also called curds in some
Fermenting milk to produce cheese with its major by-product, whey
Using the by-products, skim milk and whey, to produce ice cream, cheese and
whey based drinks
Adding ingredients to heated milk to produce a variety of sweets such as
Further processing, such as adding acids to coagulate the milk, produces
different kinds of sweets
Using cheese in cooking to produce high-value products such as cheesecakes.
Adding value to raw milk can be undertaken on an individual farm or a group of farms,
using a larger, and often more reliable, supply of the raw product. Developing such as
cottage industries has several requirements that need to be considered. These include:
A regular supply of quality milk that can be further economically processed
Infrastructure to support the processing at the farmer, village and regional levels
Organizational support for farmers and farming communities to develop the
Infrastructure for marketing the final products.
2.2 Why Process the MILK??
There are many reasons to process milk into dairy products, such as the following:
Many dairy products can be kept longer than fresh milk therefore the milk does
not have to be consumed immediately.
The demand for fresh milk may be limited, and there may be more interest in
If the daily amount of fresh milk for sale is limited, it may be more economical
to process the milk into less perishable products, store them, and sell them later
in greater quantities.
There may be no market for fresh milk close by, and only preserved products
can be sold at markets at a greater distance.
Greater financial gain may be obtained.
2.3 Processing of Milk:
Processing of milk involves following steps;
Raw Milk Storage:
The whole milk should be stored at 4ºC or less in a refrigerator
within two hour after milking. Storage time at plant is maximum 72 hours. Longer
holding time allows growth of the psychrophilic bacteria which can secrete heat
resistant proteases & lipases.
One temperature treatment that is used to control bacterial numbers is
Thermization. Milk is heated at 57-68 ºC for 15 seconds. This is only effective if milk
is cooled at 4 ºC after treatment. This is applied to raw milk that is to be stored for
several days prior to use. Its purpose is to reduce the gram-negative psychrotrophic
spoilage organisms. (Enzyme production)
Cleaning & De-creaming (Separator/Filtration):
Once the milk has been collected, cooled, and transported to the
processing plant, it is first clarified and that means all particulate matter is removed.
This takes advantage of the different densities of the particulates and the milk matrix;
essentially a decanting process. It can be quiescent (settling out) or removal by
centrifugation. Centrifugal force is used to remove bacteria and their spores.
Clarification: Removal of small particles …straw, hair etc. from milk; 2 lb/2,642 gal..it
is based on density
Bactofugation: Centrifugal separation of microorganisms from milk: Bacteria and
particularly spores have higher density than milk. Two-stage centrifugation can reduce
spore loads up to >99%. Optimal temperature for clarification is 55-60ºC
Microfiltration: Micro-filter membranes of 1.4 mm or less can lead to reduction of
bacteria and spores up to 99.5-99.99%
Definition: “Treatment of milk or a milk product to insure breakup of fat globules such
that no visible cream separation occurs after 48 h at 40ºF (4.4ºC)”
Homogenization breaks up the oil droplets in milk and prevents the cream from
separating out and forming a layer. This is of particular importance for sterilized milk
which has a long shelf-life and when the formation of a cream layer is not desired.
Additional changes include increased viscosity and a richer taste. Homogenizers are
more usually designed for industrial-scale production. Homogenization is a mechanical
process where milk is forced through a small passage at high velocity.
Effects of homogenization:
No cream line formation due to smaller fat globules
Whiter color & more full-bodied flavor, better mouth-feel
Homogenization most efficient when fat phase is in a liquid state
Cream >12% fat cannot be homogenized at normal pressure, high pressure
homogenization process is necessary
Pasteurization is a relatively mild heat treatment, (usually performed below 100°C)
which is used to extend the shelf-life of milk for several days. It preserves the milk by the
inactivation of enzymes and destruction of heat-sensitive micro-organisms, but causes
minimal changes to the nutritive value or sensory characteristics of a food. Some
heat-resistant bacteria survive to spoil the milk after a few days, but these bacteria do not
cause food poisoning.
The time and temperature combination needed to destroy 'target' microorganisms will
vary according to a number of complex inter-related factors. For milk, the heating time
and temperature is either 63°C for 30 minutes or alternatively 72°C for 15 seconds. Only
the former combination is possible on a small scale and for this the simplest equipment
required is an open boiling pan. Better control is achieved using a steam jacketed pan, and
this can be fitted with a stirrer to improve the efficiency of heating. Both of these are
batch processes which are suited to small-scale operation. A higher production rate may
be possible using a tubular-coil pasteurizer. This equipment has been tested and has been
successful for some fruit products but it is presently still at a developmental stage.
Ultra Heat Treatment (UHT):
Milk is heated to a higher temperature than pasteurized milk, stays fresher
longer, have longer shelf life (up to 3 months) & no bacterial growth because milk is
packaged in sterilized, air free packaging.
Sterilization is a more severe heat treatment designed to destroy all contaminating
bacteria. The milk is sterilized at a temperature of 121°C maintained for 15-20 minutes.
This can be achieved using a retort or pressure cooker. Unlike pasteurization, this process
causes substantial changes to the nutritional and sensory quality of the milk. In some
countries, flavored milk has become a very popular product.
However, sterilization is not recommended for small-scale production for the
The cost of a retort and ancillary equipment is high for the small-scale processor.
It is essential that the correct heating conditions are carefully established and
maintained for every batch of milk that is processed. If the milk is overheated, the
quality is reduced, and it may have a rather burnt taste and aroma.
If the milk is not heated sufficiently, there is a risk that micro-organisms will
survive and grow inside the bottle. In low-acid foods such as milk, many types of
bacteria including Clostridium botulinum can grow and cause severe food
Due to the potential dangers from food poisoning, the skills of a qualified food
technologist/microbiologist are required in order to routinely examine samples of
sterilized milk that have been subjected to accelerated storage conditions. This
requires a supply of microbiological media and equipment.
In summary, the process of sterilization requires a considerable capital
investment, the need for trained and experienced staff, regular maintenance of
sophisticated equipment, and a comparatively high operating expenditure.
78% of milk sold in the PAKISTAN is fortified with Vitamins A and D.
Some milk is also fortified with extra protein and extra calcium.
Pasteurization does not destroy all of the microorganisms therefore the milk has to
be cooled rapidly to prevent the growth of surviving bacteria. Cooling can be achieved on
a small scale by using a bottle-cooling system.
Storage, Filling & Packaging:
Pasteurized milk has a shelf-life of 2-3 days if kept at 4°C. Maintaining this low
temperature causes a substantial increase to the cost of transportation and distribution and
is therefore a major disadvantage to the development of a small-scale pasteurized milk
business. If packaged in sealed bottles and stored at room temperature, sterilized milk
should have a shelf-life in excess of six months.
Functions of packaging:
Enable efficient food distribution
Maintain product hygiene
Protect nutrients and flavor
Reduce food spoilage
Convey product information
Glass bottles (translucent vs. dark): can be reusable or recyclable
Unit 3: Milk Products:
3.1.1 Whole Milk: Contains not less than 3.25% milk fat (fat solids) and 8.25% non-fat
solids. Addition of vitamins A and D is optional, but if added, vitamin A must be present
at a level of not less than 2,000 International Units (I.U.) per quart. If added, vitamin D
must be present at 400 I.U. per quart.
3.1.2 Cultured Milk: Contains not less than 3.25 percent milk fat (fat solids) and
8.25% non-fat solids. Culturing any of the following milk products alone or in
combination produces it: cream, milk, partially
3.1.3 Half and Half: Consists of a mixture of milk and cream containing not less that
10.5% milk fat, but less than 18% milk fat.
3.1.4 Evaporated Milk: Evaporated milk is made by removing about 60% of milk’s
water. It contains not less than 6.5% milk fat, not less than16.5% non-fat solid; and not
less than 23% by weight of total milk solids. Evaporated milk is a heat-sterilized
product with an extended shelf life with a yellowish color and cooked flavor.
3.1.5 Sweetened Condensed Milk: This product results from the removal of about
60% of the water from a mixture of milk (whole and nonfat pasteurized, homogenized
milks) and carbohydrate sweeteners such as sucrose. This product contains not less than
8% milk fat and not less than 28% total milk solids. It is obtained by removal of water
only from pasteurized skim milk (unless otherwise indicated).
3.1.6 Non-fat Dry Milk: Nonfat dry milk is made by removing water from pasteurized
skim (non-fat or fat free) milk. The product contains not more than 5% by weight of
moisture, and not more than 1.5% by weight of milk fat (unless otherwise indicated).
After leaving milk to stand for about 24 hours at as low a temperature as possible
(4-12°C), the cream can be skimmed off using a spoon or saucer. This method makes
use of the fact that cream rises and then stays on top of the milk. It contains most of the
milk fat. Only cow milk readily produces cream this way; other kinds of milk need a
hand creamer (centrifugal milk separator) to separate cream and milk.
3.2.1 Light Cream: It contains not less than 18% milk fat, but less than 30%. Light
creamy also be called “coffee cream” or “table cream.”
3.2.2 Light Whipping Cream: Contains not less than 30% milk fat, but less than 36%
milk fat. It may also be called “whipping cream.”
3.2.3 Heavy Cream: Contains not less than 36% milk fat. Heavy creamy also be called
“heavy whipping cream.”
3.2.4 Sour Cream: The product resulting from the addition of lactic acid-producing
bacteria to pasteurized cream containing not less than 18% milk fat. Sour creamy also
be call “cultured sour cream.”
3.3.1 Dry Curd Cottage Cheese: A soft, un-ripened cheese made from skim milk
and/or reconstituted nonfat dry milk. The cheese curd is formed by the addition of either
lactic acid-producing bacteria (cultured) or acidifiers (directly adding lactic acid). The
latter process is called direct acidification. Rennet and/or other suitable enzymes may be
used to assist curd formation. Dry curd cottage cheese contains less than .5% milk fat
and not more than 80% moisture. The product may also be called “cottage cheese dry
3.3.2 Cottage Cheese: The product resulting from the addition of a creaming mixture
(dressing) to dry curd cottage cheese. Cottage cheese contains not less than 4% milk fat
and not more than 80% moisture.
Yoghurt is produced when milk is soured by certain lactic acid bacteria, which prefer
growing temperatures far above room temperature: 37 – 45°C. The milk should first be
heated to 85°C or higher. A high pasteurization temperature (above 72°C) gives a better
consistency (thickness) to the final product. After the milk has been soured, the
resulting yoghurt can be used to make more fresh yoghurt by adding it to fresh milk.
Yogurt: The product resulting from the culturing of a mixture of milk and cream
products with lactic acid-producing bacteria, Lactobacillus bulgaricus and
Streptococcus thermophilus. Yogurt contains not less than 3.25% milk fat and 8.25
percent non-fat solids.
3.4.1 Low fat Yogurt: Similar in composition to yogurt except that it contains not less
than .5% milk fat and no more than 2% milk fat.
3.4.2 Non-fat Yogurt: Similar in composition to yogurt except that it contains less
than .5% milk fat.
During churning the cream, sour cream or sour milk will be mixed intensively
with air. This process causes fat globules to flocculate (or stick together), producing
butter and buttermilk.
The simplest way to make butter from small quantities of milk is by using a bottle
or a jar that can be covered with a well-closing lid or a simple bowl with beaters. If
large quantities of milk or cream are available, you should consider acquiring a real
churn. There are several types available. The churn tub is a simple method, which is
often used in the tropics. A cheap and practical domestic churn is a glass pot with a
paddle attached to a screw top. The paddle can be turned manually. This churn is
difficult to clean. It is best to rinse it with water before use, in order to prevent the butter
from sticking to the sides.
Churns should not be filled more than one third with soured milk or sour cream.
Churn with a regular up and down or sideways movement. Stop churning when the
butter particles reach the size of rice grains or peas and the buttermilk looks rather
liquid. If, after 30 minutes, no grains have yet been formed, you can change the
temperature by adding a little clean cold or warm water. See also the remarks at the end
of this chapter. The amount of added water should never be more than 25% of the total
amount of churned cream or milk. The butter particles will float to the top of the
buttermilk, because butter is lighter than buttermilk. This makes it easier to separate the
two products by pouring off the buttermilk through a coarse sieve. Never add too much
water, otherwise the buttermilk will become too watery.
To make ghee, you will need:
• a heat source
• a pan
• a metal spoon.
Heat the butter until water and fat form separate layers; the fat will float on top. There
are two ways to remove the water:
It can be removed by further heating. The water present will evaporate.
It is possible to remove the layer of fat with a spoon.
This fat should then be heated again. The scum, which will form, has to be skimmed off
regularly, preferably with a skimmer. The color of ghee can vary from almost white to
dark brown. A rancid flavor is acceptable, but if it tastes burnt it should be discarded.
3.7 Koa (Khoa):
Koa or khoa is a type of concentrated milk. You will need:
• fresh (un-boiled) whole or skimmed milk
• a heat source
• a shallow, clean, wide, iron pan with a thick, flat bottom
• a flat, clean metal utensil to stir with (e.g. a flat pancake spatula).
Fill the pan with the milk up to 30 to 50% of its capacity. Bring the milk to boiling,
stirring continuously. The water will evaporate and after some time the milk will reach a
certain viscosity this means the milk will thicken. Take great care to scrape the sides of
the pan during stirring. Once the milk has reached a dough-like consistency and stirring
does not prevent the mass from sticking to the side of the pan, you can remove it from
the heat source and lower the temperature by at least 20°C. At this point the water
content should have been reduced to about 40% of what it was. Take the lump of koa
out of the pan, put it on a cold surface and flatten it. After cooling, the koa will be firm
and can be cut into squares. It will have a sweet, nutty flavor. Koa can be kept only for
about 2 - 5 days because of possible re-infection. The preparation of koa requires much
time (a few hours) and fuel, on top of which 1 liter of milk produces only 0.4 liters of
Unit 4: Milk By-Products:
During the manufacture of different dairy products, the inevitable problem of
utilization of by-products is encountered. Because of their unique and important nutrients
available in the by-products, they have to be utilized in a proper manner considering the
welfare of the general masses.
Conversion of edible nutrients into non edible substances will not augur well given
the rampant malnutrition staring at the face of the impoverished developing countries.
The profitability of the dairying can be greatly improved by economically utilizing the
dairy by-products and it can be considered as a prerequisite to profitable dairy business.
With the advancement in technology, the scope is wide open for creating newer channels
of utilization of the by-products arising from dairy processing.
4.1 whey watery part of milk produced when raw milk sours and coagulates. It
has low solid & high lactose.
4.1.1 Acid whey: drained from cheese curd acidified to 4.6 by cultures (or
acid). E.g. Cottage cheese
4.1.2 Sweet whey: drained from curd formed by rennet coagulation. E.g.
4.2 Skimmed milk or skim milk. Culturing normally involves the addition of
certain charactering ingredients and lactic-acid producing bacteria. An example
of cultured milk is buttermilk.
Sterilized flavored milk
Concentrated sour skim milk
Plain and Sweetened Condensed skim milk
Dried skim milk or Skim milk powder or
Non Fat Dry Milk NFDM)
Cottage cheese, edible casein
Fermentation ,Concentration Condensed buttermilk
Whey beverage, Yeast whey
Plain and sweetened condensed whey,
whey protein concentrate, whey paste,
Sweetmeat, Toffee, Sweet paste