COCOA/ CHOCOLATE
The cocoa tree (Theobroma
cacao) is a native of the dense tropical forests of the Amazon. The
term “Theobroma” means “food of the Gods”. The word
cocoa has originated from the Aztec word “Cacahuati”. Cocoadescribes
the bulk commercially dried, fermented beans, as well as powder from cocoa
beans. The main procedures and exporters of the cocoa bean are West Africa (74%
of the world production), North, Central and South Africa (21%)
and Asia and Australia (3%). However the processing of the bean
into chocolate is done in several other countries and some of the best
chocolate is produced in Belgium,Switzerland and France.
The Cocoa Plant
The cocoa plant is
a small tropical tree, originally grown in South and Central America; but now
commercially grown in West Africa. The cocoa tree requires a good soil, a
huge rainfall and a low altitude. The part of the plant that is processed and
used for the making of cocoa and chocolate is the fruit that grows on the main
trunk of the tree, as well as on the branches. The fruit is a large pod
4“ to 12“ in length and about 4“in diameter and has a hard leathery
rind containing 25-75 seeds in distinct rows, embedded in a soft pulp.
Classification
Cocoa may be
classified under the following headings:
1. By the country
of origin (Zambia/Mozambique).
2. By the
species of the bean (Criollo/Forastero).
3. By the
method of manufacture (For drinking chocolate/for milk chocolate).
4. By their
particular use (Vending machines/Icings/Chocolate moulding).
Processing
of Cocoa
The processing of
cocoa bean into cocoa powder is done in seven stages, as mentioned under:
1. Fermentation
of the Beans
The ripe cocoa pods are collected and split open and the beans and the pulp surrounding them are scooped out and put into a fermentation chamber, also called the sweat boxes, where the temperature is allowed to rise to 40 to 50°C (104 to 122°F). Fermentation will kill the germs and prevent germination and decomposition of the bean. It will also encourage enzyme reaction reducing the bitterness and developing flavour. The beans absorb the liquid from the fermenting sugary pulp which will then turn into alcohol and finally into acetic acid. As soon as the mass turns into the acid state, the fermentation is stopped. Otherwise unpleasant flavours and odours will develop.
The ripe cocoa pods are collected and split open and the beans and the pulp surrounding them are scooped out and put into a fermentation chamber, also called the sweat boxes, where the temperature is allowed to rise to 40 to 50°C (104 to 122°F). Fermentation will kill the germs and prevent germination and decomposition of the bean. It will also encourage enzyme reaction reducing the bitterness and developing flavour. The beans absorb the liquid from the fermenting sugary pulp which will then turn into alcohol and finally into acetic acid. As soon as the mass turns into the acid state, the fermentation is stopped. Otherwise unpleasant flavours and odours will develop.
2. Drying of the Beans
This is done by laying the beans thinly out in the Sun to dry and occasionally turning them over, or by passing them through a mechanical drying chamber. When completely dried, there will not be more than 4% moisture in the bean. At this stage, beans are exported, unless they are to be processed into cocoa chocolate.
This is done by laying the beans thinly out in the Sun to dry and occasionally turning them over, or by passing them through a mechanical drying chamber. When completely dried, there will not be more than 4% moisture in the bean. At this stage, beans are exported, unless they are to be processed into cocoa chocolate.
3. Roasting the Beans
This stage is essential to develop the flavour and the aroma of the bean and to give colour. Moisture is lost at the stage, which assists in the removal of the shell from the beans.
This stage is essential to develop the flavour and the aroma of the bean and to give colour. Moisture is lost at the stage, which assists in the removal of the shell from the beans.
4. Removing the Shell
This stage is also called “Winnowing”. The shell is removed from the bean by passing them through a series of rollers and sieves. The de-shelled beans, now mostly broken bits and pieces, are referred to as “Nibs”.
This stage is also called “Winnowing”. The shell is removed from the bean by passing them through a series of rollers and sieves. The de-shelled beans, now mostly broken bits and pieces, are referred to as “Nibs”.
5. Alkalization of the Nibs (Dutch
Processing)
This stage, that further develops the flavour and colour, is usually done by tumbling the nibs in an alkali solution. After drying, the nibs may be roasted to correct the moisture content.
This stage, that further develops the flavour and colour, is usually done by tumbling the nibs in an alkali solution. After drying, the nibs may be roasted to correct the moisture content.
6. Grinding the nibs
The nibs are now ground into very small particles, a process which releases a large amount of fat and results in the mass becoming a thick syrup. This fat is known as “Cocoa Butter”, usually 50% of the nibs.
The nibs are now ground into very small particles, a process which releases a large amount of fat and results in the mass becoming a thick syrup. This fat is known as “Cocoa Butter”, usually 50% of the nibs.
7. Extraction of the Cocoa Butter
The cocoa fluid/mass is then fed into large felt lined steel pans fitted with a movable perforated lid. When subjected to hydraulic pressure, some of the fat is forced through the filter cloths, leaving behind a solid residue, known as the “Press Cake”. This is removed from the pan, allowed to cool, then pulverized and sieved. TO this fine powder, a small amount of salt and vanilla is usually added before it is marketed as the popular cocoa powder.
The cocoa fluid/mass is then fed into large felt lined steel pans fitted with a movable perforated lid. When subjected to hydraulic pressure, some of the fat is forced through the filter cloths, leaving behind a solid residue, known as the “Press Cake”. This is removed from the pan, allowed to cool, then pulverized and sieved. TO this fine powder, a small amount of salt and vanilla is usually added before it is marketed as the popular cocoa powder.
Plain Chocolate
The processing of
chocolate involves the first six stages as for the processing of cocoa and then
a further three stages:
1. Mixing
the Cocoa mass with sugar
The cocoa mass is thoroughly mixed with powdered sugar in large blending kettles. The fat content is strictly controlled to obtain a standard product. Additional cocoa butter may be added to adjust the consistency.
The cocoa mass is thoroughly mixed with powdered sugar in large blending kettles. The fat content is strictly controlled to obtain a standard product. Additional cocoa butter may be added to adjust the consistency.
2. Refining
the mixture
This is done by passing the mixture through a series of five heavy rollers to reduce the size of the non-fat particles, so that the chocolate will be smooth to the palate. This stage exposes the particles to the air, reducing the moisture content, partially evaporating volatile substances, and lightening the colour of the mixture.
This is done by passing the mixture through a series of five heavy rollers to reduce the size of the non-fat particles, so that the chocolate will be smooth to the palate. This stage exposes the particles to the air, reducing the moisture content, partially evaporating volatile substances, and lightening the colour of the mixture.
3. Conching
The final stage is concerned with producing a standard quality of chocolate. Conching is the mechanical agitation of the chocolate mass with additional cocoa butter at a temperature of 60-70°C (140-158°F). This will further evaporate volatile substances and also develop the flavour. Additional flavourings may also be added at this stage and the mixture is standardized. The chocolate is then set in moulds such as bars, slabs and is also known as courverture.
The final stage is concerned with producing a standard quality of chocolate. Conching is the mechanical agitation of the chocolate mass with additional cocoa butter at a temperature of 60-70°C (140-158°F). This will further evaporate volatile substances and also develop the flavour. Additional flavourings may also be added at this stage and the mixture is standardized. The chocolate is then set in moulds such as bars, slabs and is also known as courverture.
A chocolate in
block has a tendency to collect moisture from the air and this can be seen in
the form of beads of perspiration. This could be wiped carefully and well
scraped before being used for dipping.
Milk Chocolate
The processing of
milk chocolate is the same as Plain Chocolate(courverture),
except that milk crumb is added at the refining stage and the
conching is done at a lower temperature, but for a longer time. Milk crumb is a
mixture of condensed milk and chocolate mass, reduced to a powder form.
Cocoa Powder
It is a product
obtained by grinding roasted cocoa beans to an oily liquid, pressing this in a
cocoa-butter press, to remove about half cocoa butter and then grinding the
residual press cake to a powder. Chocolate powderis a blend of true
cocoa powder, sugar and starch.
Drinking Chocolate
It is a modern
beverage drink, prepared from the chocolate powder or chocolate flakes and made
in similar manner to the cocoa drink, by adding hot water or milk.
White Chocolate
It is a product
composed of pure cocoa butter, full of cream milk powder and sugar, milled
together and passed through refining rolls. As pure cocoa butter has a strong
taste and odour of chocolate, the product is similar in flavour to chocolate.
It can be tempered and molded. Provided fat-soluble edible colours are used,
white chocolate can be coloured pink, orange, yellow or green.
Chocolate Spread
It is permanently
soft, pasty or semi-liquid product, which can be used in bakery as flavouring
and colouring material for fillings, butter creams and fondants. To make it,
add warmed golden syrup to melted chocolate courverture in the proportion of
two parts of syrup to one part of courverture, mixing them thoroughly and
adding the warm syrup into glass or glazed earthen ware jars and kept for use
as needed.
Panache
It is the name
given to a blend of chocolate and cream. Boiling fresh cream is mixed with
grated or melted courverture and stirred occasionally till cooled.
Composition
of Cocoa and Chocolate
Theobromine is the stimulant in cocoa and
chocolate, along with somecaffeine. The other major constituents of
cocoa and chocolate include colour and flavour compounds, lipids and
carbohydrate. The purple colour is due to the presence of anthocyanins. The
chocolate flavour is contributed by the phenolic compounds.
Starch is the chief
carbohydrate in cocoa and chocolate and functions as a thickening
agent. Cocoa contains 11% starch while chocolate contains
8%. Cocoa has more thickening power than chocolate because of its
high starch content. For this very reason, cocoa is not substituted on a direct
weight basis for chocolate. Usually 3-3.5 tablespoon of cocoa powder plus ½
table spoon of fat are considered equivalent to 30 Gms of chocolate.
Fat constituent of
cocoa and chocolate is cocoa butter. Cocoa varies in fat content from
10-22%. Chocolate contains 50% fat. The low melting temperature of chocolate (near
32°C) imparts a smooth texture and readily releases flavour components.
Uses of Chocolate
Cocoa powder and
Chocolate powder are used:
1. As a hot
beverage.
2. AS a
flavouring agent.
3. As a
colouring agent.
4. For hot and
cold sauces.
Courverture is
used:
1. As a
coating.
2. As a
decoration (Piping).
3. Formoulding
into Easter eggs etc.
4. For sauces.
5. For
ice-creams.
Storage
Cocoa and
chocolate deteriorate quickly in the presence of moisture and
heat. Cocoa becomes grayish in colour and lumpy when stored at
temperature above 16-21°C and in high humidity.
A mottled or grey
surface known as bloom may develop on the chocolate when it is
exposed to high heat and moisture. The melting fat and re-crystallizing in a
different pattern on the surface contribute to the formation of bloom.
Appropriate
tempering procedures during processing and the use of stabilizers retards the
development of bloom. Sugar bloom, a rough greyish layer, may
develop on sweet chocolate due to moisture; the dissolved sugar re-crystallizes
on the surface.
The chocolate
flavour appears not to be altered by the development of bloom or lumping of
cocoa products, but the texture may be grainy. Milk chocolates also absorb
flavours and odours when stored improperly. The quality of cocoa and chocolate
is best when high temperature and humidity is avoided. The best protection is
tightly sealed containers kept in a cool, dry place.
Nutritional Aspect
Cocoa powder and
milk chocolate are rich in fats and carbohydrates. Being a highly palatable and
energy concentrated food, it was used extensively in emergency situations such
as wars and during rescue and evacuation situations.
Chocolate Tempering
Chocolate tempering
is a process used to prepare pure chocolate liquor for cooking purposes. During
tempering, it is essential that not one drop of water should come into contact
with the chocolate
Procedure
Break chocolate
into small pieces and place it in a bowl over hot water. Stir occasionally
until it is melted and the temperature is 46-48°C If this temperature is
exceeded, the chocolate is ruined.
Remove the bowl
from saucepan and set in iced water, stirring carefully until the chocolate
begins to set on the bottom. Then warm the chocolate carefully over hot water
until the temperature is dark chocolate to 31°C, in milk chocolate to 29°C and
in white chocolate to 29°C. If the temperatures are exceeded, the tempering
process should begin again.
It is only
necessary to temper chocolate when using it for moulding or dipping. For any
fillings, pure chocolate or cooking chocolate can be used without tempering.
BUTTER
Butter is the fat
of cream that is separated completely
from the other milk constituents by agitation or churning. The mechanical
rupture of the protein film around the fat globules allows the fat globules to
clump together. Butter formation is an example of breaking of an oil-in-water
emulsion by agitation. The resulting emulsion that forms in butter itself is a
water-in-oil emulsion, with about 18% water being dispersed in 80% fat and a
small amount of protein acting as an emulsifier.
Butter is made from
either sweet or sour cream. Butter from sour cream has a more pronounced
flavor. The cream may be allowed to sour naturally or may be acidified by the
addition of pure culture of lactic acid bacteria to sweet cream, which produces
a butter of better flavor and keeping quality.
It consists of more
than 80% butterfat and small amounts of protein, vitamin A and D, minerals,
lactose and water. Butter must have a minimum of 80% fat content, a non-fat
solid content of 2% and a maximum of 16% moisture (water).
Composition
Average composition of Butter
|
|
Fat
|
82.5%
|
Protein (Casein)
|
1.5%
|
Lactose
|
2%
|
Salt
|
2%
|
Water
|
12%
|
Factors that affect
quality of Butter
1. The breed
of animal (cow or buffalo) from which the milk was obtained.
2. The type of
feed that was available for the animal.
3. The method
of manufacture (fresh or ripened cream).
4. The
efficiency of manufacture (wrong temperature may affect the color and flavor
of butter).
5. Whether the
butter was blended.
6. The
addition of salt and color.
7. The method
of packing and storing.
Classification of
Butter
There are four main
types of butter:
1. Fresh or
Sweet Cream Butter,
2. Ripened
cream or Lactic Butter,
3. Blended or
Milled Butter and
4. Special
Butter
(Fresh and
ripened cream Butters are known as “Creamery Butters”).
Manufacture of
Creamery Butter
The manufacture of
creamery butter takes place in four main stages, as mentioned:
1. Holding
The cream (35%) is pasteurized at 95°C (203°F) and held for 2 to 4 seconds. It is then cooled to 4.5°C (40°F) and held there for several hours to ensure the uniform hardening of the fat globules.
The cream (35%) is pasteurized at 95°C (203°F) and held for 2 to 4 seconds. It is then cooled to 4.5°C (40°F) and held there for several hours to ensure the uniform hardening of the fat globules.
2. Ripening
When the end product is going to be a ripened butter or lactic butter, a “starter” (which is a laboratory culture of acid-producing bacteria) will be added during the Holding stage, in which the holding temperature will be 15.5-18.5°C (60-65°F) for 3 to 4 hours before being cooled to 4.5°C (40°F). This gives the butter a much fuller flavour. However, the flavour tends to fade and therefore the ripened cream butter has a shorter life than the sweet cream butters. This stage will be omitted when making the sweet cream butter.
When the end product is going to be a ripened butter or lactic butter, a “starter” (which is a laboratory culture of acid-producing bacteria) will be added during the Holding stage, in which the holding temperature will be 15.5-18.5°C (60-65°F) for 3 to 4 hours before being cooled to 4.5°C (40°F). This gives the butter a much fuller flavour. However, the flavour tends to fade and therefore the ripened cream butter has a shorter life than the sweet cream butters. This stage will be omitted when making the sweet cream butter.
3. Churning
The churning of cream is done in large stainless steel churns that hold about 1000 gallons of cream. The temperature must not exceed more than 4°C. The churns are rotated while internal rollers pass through the cream. This breaks the envelope of non-fat particles/solids that surround the small fat globules and coalesce to form larger groups of butter fat. The envelope is dispersed in the thin liquid part of the cream to form buttermilk. After about 30 minutes of churning, the butter separates out in the form of grains and floats in the buttermilk. The buttermilk is carefully drained away and used for other purposes.
The churning of cream is done in large stainless steel churns that hold about 1000 gallons of cream. The temperature must not exceed more than 4°C. The churns are rotated while internal rollers pass through the cream. This breaks the envelope of non-fat particles/solids that surround the small fat globules and coalesce to form larger groups of butter fat. The envelope is dispersed in the thin liquid part of the cream to form buttermilk. After about 30 minutes of churning, the butter separates out in the form of grains and floats in the buttermilk. The buttermilk is carefully drained away and used for other purposes.
4. Washing
and Salting
The butter grains are now washed with ice water to remove any traces of buttermilk left on the surface of each grain, in order to maximize the keeping quality. Ice water also helps to harden butter grains. Salting can be done in two ways:
The butter grains are now washed with ice water to remove any traces of buttermilk left on the surface of each grain, in order to maximize the keeping quality. Ice water also helps to harden butter grains. Salting can be done in two ways:
a. By adding
fine grains of dairy salt, and
b. By soaking
in a brine solution for 10-15 minutes and allowing the butter to absorb it.
The quantity of
salt added usually average 1% for ripened cream butter and 1.5% for fresh cream
butter. Salt contributes to flavour and improves the keeping quality.
The butter grains
are then worked into a smooth solid mass by rotating the churns slowly for
10-15 minutes, then weighed and packed. Colouring (annatto) may also be
added at this stage. If unsalted butter is required, the salting stage is
omitted.
Blended Butter
Blended butter is a
blend of butters from different regions or countries. These are mixed together
to produce a product of standard quality at a competitive price, under a brand
name.
Special Butters
This group includes
some butter that are not commonly available and those which are not true
butters. These include:
1. Whey
Butter
Whey is the liquid which separates from the curd while making cheese. The butterfat obtained from the whey may be used to produce butter, or it may be added to fresh cream/milk prior to it being processed into butter. Due to its origin, this butter has a faint cheesy flavour.
Whey is the liquid which separates from the curd while making cheese. The butterfat obtained from the whey may be used to produce butter, or it may be added to fresh cream/milk prior to it being processed into butter. Due to its origin, this butter has a faint cheesy flavour.
2. Milk
blended Butter
Quantities of milk are blended into butter, thereby increasing the moisture content to 24% (max.).
Quantities of milk are blended into butter, thereby increasing the moisture content to 24% (max.).
3. Powdered
Butter
This is spray-dried butter containing 80% milk fat and non-fatty solids. It is produced on a large scale in Australia and is used mainly in the Bakery trade.
This is spray-dried butter containing 80% milk fat and non-fatty solids. It is produced on a large scale in Australia and is used mainly in the Bakery trade.
4. Compound
Butters
These are made by adding a particular natural flavour or colour to butter, depending on the type of food with which it is served. It is generally used as an accompaniment e.g. Lobster Butter, Parsley Butter etc.
These are made by adding a particular natural flavour or colour to butter, depending on the type of food with which it is served. It is generally used as an accompaniment e.g. Lobster Butter, Parsley Butter etc.
5. Cocoa
Butter
This is not a true butter, rather obtained by crushing the cocoa beans. It is the most expensive ingredient used in chocolate making. Cocoa butter substitutes, using palm oil, are also available.
This is not a true butter, rather obtained by crushing the cocoa beans. It is the most expensive ingredient used in chocolate making. Cocoa butter substitutes, using palm oil, are also available.
6. Peanut
Butter
It is a paste-like substance obtained by grinding roasted peanuts that may be further emulsified and flavoured.
It is a paste-like substance obtained by grinding roasted peanuts that may be further emulsified and flavoured.
Uses of Butter
1. As a spread
for bread, toast and scones.
2. As a basic
ingredient in pastry-making and cake-making.
3. Used as an
accompaniment (compound butter).
4. To enhance
the taste and flavour of soups and sauces.
5. As a
cooking medium (The smoke point of butter fat is only 127-130°C; so a
vegetable oil should be used when high cooking temperatures are required).
6. For butter
sculptures.
Butter is available
in 10 Gms, 100 Gms and 500 Gms packs in the market.
Storage
Butter is a
perishable product and tends to loose flavour and go rancid on prolonged
storage. Exposure to sunlight can make it go rancid faster.
It must be stored
at refrigerated temperatures (2°C), well wrapped and away from strong
flavoured foods, for it absorbs odours and flavours easily. If purchased in
bulk, it can be frozen at -25 to -35°C.
A good
quality butter should have a clean flavour and aroma characteristic of
the type of butter, have a close body, a waxy texture, be of uniform colour,
have a uniform distribution of salt (if added), be clean in appearance
and have an absence of any free moisture.
Ghee is obtained by
clarifying butter. Butter is heated to evaporate water. Pure ghee has a higher
keeping quality and is a good cooking medium and a shortening agent used in
Indian Cuisine.
CREAM
Cream is the fat
separated from milk. It is the lighter portion of milk containing all the main
constituents of milk, but in which fat content is high and the solid (non fat)
content is lower.
Cream is
commercially separated from milk in a creamery, by means of a
mechanical separator. The milk is first heated to between 32-49°C (90-120°F)
before being run into the separator which operates like centrifugal machine,
rotating at very high speed and forcing the milk, which is heavier, to the
outside; while the cream, which is lighter, remains at the centre. The cream
and the skimmed milk are drained out through separate outlets and by means of a
control valve, the fat content is adjusted. The skimmed milk is then heated to
79.5°C (175°F) to kill off any harmful bacteria before being further processed
into dried milk etc.
Types of Cream
There are a variety
of creams available in the market, each having a different fat content:
Type of Cream
|
Fat Content
|
Single Cream
|
18%
|
Whipping Cream
|
35%
|
Double Cream
|
48%
|
Double Thick
Cream
|
50%
|
Sterilized Half
Cream
|
12%
|
Sterilized Cream
|
23%
|
Clotted Cream
|
55%
|
For general
purposes, cream may be classified into:
1. Whipping
Cream (>30% fat).
2. Light or
Coffee Cream (18% fat).
3. Half-and-half
(10.5% fat).
4. Non-dairy
or Manufactured Cream.
Half-and-half is a
mixture of milk and light cream and it may be used in place of coffee cream.
Cream containing sugar, stabilizers and flavoring is sold in pressurized
containers. Non-dairy products containing water, vegetable fat, sugar, sodium
caseinate, emulsifiers and vegetable gums are also available in pressurized
cans. Nondairy products for whipped toppings, coffee, whiteners and snack dip
bases are also available in the market.
Manufactured Cream
1. Reconstituted
Cream
It is made by emulsifying butter with skimmed milk or skimmed milk powder. This is not true cream, but a substance which resembles it in appearance.
It is made by emulsifying butter with skimmed milk or skimmed milk powder. This is not true cream, but a substance which resembles it in appearance.
2. Imitation
or Synthetic Cream
It is made by the emulsification of vegetable fats with dried egg and gelatin, and then sugar and flavorings are added. It is a product which is frequently used in catering and baking trade, but which is very easily contaminated and liable to cause food-poisoning.
It is made by the emulsification of vegetable fats with dried egg and gelatin, and then sugar and flavorings are added. It is a product which is frequently used in catering and baking trade, but which is very easily contaminated and liable to cause food-poisoning.
Uses of Cream
1. To serve
with hot or cold coffee and chocolate.
2. To serve as
an accompaniment (fruit based salad).
3. To be used
for decorative purposes in cakes and gateaux and for garnishes in soups and
desserts.
4. As a main
ingredient in certain desserts such as ice-cream and custards.
Storage of Cream
Fresh cream must be
treated in the same way as fresh milk, as far as storage is concerned. Whipped
cream must be covered and stored in sterilized containers in the refrigerator
and used in the same day. Reconstituted and intimation cream must be
refrigerated, and only small quantities be whipped, when required for immediate
use.
The whipping of
Cream
Whipping cream is a
product that results from the agitation of cream. During whipping, air is incorporated,
thus forming foam, and fat particles are clumped together, producing the
characteristic stiffness or rigidity of whipped cream. If whipping is continued
too long, the emulsion breaks, and butter gets separated. The air bubbles
formed in whipped cream are surrounded by protein films in which clumps of fat
globules offer structural support, which increases the rigidity of the foam and
permits the formation of more air bubbles and the extension of the protein film
to surround them. Homogenized cream is not suitable for whipping.
Points to be
considered while whipping Cream
1. Use cream
with minimum 30% fat for ease in whipping and for a stiff product. Increased
fat up to 38% improves the whipping quality of cream.
2. Hold cream
at low temperature (7°C) whips well. Lower temperature increases viscosity,
which increases the whipping property. The beater and the bowl used should be
cold.
3. Whipping
property improves with the aging of cream, as viscosity increases.
4. Homogenized
cream will not whip satisfactorily. When whipping cream, tiny air bubbles are
trapped and surrounded by the fat globules in the cream. Homogenized cream will
have had the majority of the fat globules broken down and they will not be
sufficient and strong enough to trap and hold the air cells.
5. The
utensils must be sterilized. Glass or stainless-steel containers are ideal for
whipping cream. Avoid using aluminum as it tends to discolor the cream, turning
it a dull grey.
6. Increased
acidity up to the concentration required to give a sour taste (0.3%) has
no effect on whipping quality.
7. Addition of
sugar decreases both volume and stiffness and increases time required to whip
cream if it is added before whipping. If sugar is to be added, it is best added
after the cream is stiff or just before service.
MILK
Milk is the natural
food for mammals in the first stages of life. It is thenear-perfect single
food containing protein, carbohydrate, fat, minerals and vitamins. However, it
is lacking in iron, vitamin C and D. It is one of the most complete
foods, because it contains the nutrients required for growth and development.
Milk obtained from several species of animals is used for human consumption,
but the most popular are cows, buffaloes and goats’ milk.
Composition
Components
|
Cow’s milk
|
Buffalo’s milk
|
Water
|
85-87%
|
80%
|
Carbohydrate
|
5%
|
5%
|
Protein
|
3%
|
4.5%
|
Fat
|
4%
|
9%
|
Vitamins and
Minerals
|
1%
|
1.5%
|
However, the
composition doesn’t always remain the same. This will vary slightly, depending
upon the species, the age and the feed of the animal. It will also depend upon
the lactation period and as animal advances in age, the fat content will also
increase. Animals who feed on grass pastures produce a high yield of milk,
richer in Vitamin A.
Nutritive Value
Protein
Some of the most complete
forms of protein are found in milk. Casein is the main milk
protein. It is insoluble in water and is very easily precipitated by acids.
This results in the curdling of milk. Lactoglobulinand Lactalbumin are
the other two proteins that are found in milk. They coagulate easily on heating
and are responsible for the precipitate found at the bottom and the sides of
the pan used for the heating of milk. They are not easily precipitated by acid.
Carbohydrates
The main
carbohydrate found in milk is Lactose or milk sugar.
Lactose is not very soluble in water and it is responsible for the sweet taste
in milk. Lactose also tends to crystallize in milk powder during storage and
results in lump formation and caking. It isn’t water soluble and is responsible
for the sandy or gritty texture in condensed milk and ice-cream. In the souring
of milk, lactic acid bacteria converts lactose into lactic acid, giving sour
milk its characteristic flavour.
Fat
The fat constituent
of milk is present in the form of cream. It is dispersed as fine
globules. When heated, it rises to the surface, where it forms a layer. It
contains fat-soluble vitamin A and D. Together with lactose, fat provides the
energy in the diet.
Minerals and
Vitamins
Milk is rich in
calcium, phosphorus, sodium, potassium and all the vitamins known to be
essential for human nutrition are present in milk. Milk is rich in Vitamin
A, S, E and K.
Since milk contains
a great deal of water, it is a very dilute food. Because of this, it is easy to
consume and digest. Milk is an ideal food for all, especially infants and young
children. There is no evidence that it is an indispensable constituent of the
adult diet.
Processing
From the time it is
milked from the animal to the time of sale, milk has to undergo processing to
improve the keeping quality and to make it fit for consumption. The various
stages are:
1. Collection
Milk is brought to the dairy in clean sterilized vessels, preferably stainless steel.
Milk is brought to the dairy in clean sterilized vessels, preferably stainless steel.
2. Holding
tanks
The milk is immediately transferred to holding tanks and is held at 10°C to keep it safe. Cooling is done either in a tank, jacketed with pipes in which runs a brine solution. Else the milk is run over very cold water pipes.
The milk is immediately transferred to holding tanks and is held at 10°C to keep it safe. Cooling is done either in a tank, jacketed with pipes in which runs a brine solution. Else the milk is run over very cold water pipes.
3. Filtration
The milk is passed through a series screens and filters to remove sediment and floating particles.
The milk is passed through a series screens and filters to remove sediment and floating particles.
4. Pasteurization
It is the process of heating milk to 63.7°C and holding it at that temperature for 30 minutes. This is known as the “Holder Process of Pasteurization”. Nowadays, the Flash Pasteurization is more commonly used. It is also called the HTST or High Temperature Short Time method, where the milk is heated to 71.6°C for only 15 seconds. Pasteurization makes milk safe for human consumption by destroying pathogenic germs (pathogens). It also helps to increase the shelf life. Flavour of the milk remains unaffected at pasteurization temperature.
It is the process of heating milk to 63.7°C and holding it at that temperature for 30 minutes. This is known as the “Holder Process of Pasteurization”. Nowadays, the Flash Pasteurization is more commonly used. It is also called the HTST or High Temperature Short Time method, where the milk is heated to 71.6°C for only 15 seconds. Pasteurization makes milk safe for human consumption by destroying pathogenic germs (pathogens). It also helps to increase the shelf life. Flavour of the milk remains unaffected at pasteurization temperature.
5. Homogenization
At temperature of 60°C, milk is passed under high pressure through small opening of a machine called homogenizer. The main purpose is to subdivide the fat globules in milk and disperse them evenly in the entire mass. Fat has a low density and tends to rise to the surface during heating. Homogenization prevents this by first breaking up the fat into tiny particles and then dispersing them throughout the milk. This adds to the flavour and results in a better body.
At temperature of 60°C, milk is passed under high pressure through small opening of a machine called homogenizer. The main purpose is to subdivide the fat globules in milk and disperse them evenly in the entire mass. Fat has a low density and tends to rise to the surface during heating. Homogenization prevents this by first breaking up the fat into tiny particles and then dispersing them throughout the milk. This adds to the flavour and results in a better body.
6. Bottling
The bottles of selected and uniform size have to be sterilized by steam and hot water and then they are filled with milk, which are capped automatically. Nowadays milk is filled in plastic pouches and these are more economical, easily transported and save storage space. Plastic pouches are easily disposed and are safe to handle.
The bottles of selected and uniform size have to be sterilized by steam and hot water and then they are filled with milk, which are capped automatically. Nowadays milk is filled in plastic pouches and these are more economical, easily transported and save storage space. Plastic pouches are easily disposed and are safe to handle.
7. Sterilization
The sealed bottles are now heated for 30 to 40 minutes at temperatures ranging from 104-110°C in steam chambers calledautoclaves and then allowed to cool. Milk can also be sterilized before bottling. It is subjected to temperatures of 135-150°C for just 1 second. This is called the UHT or Ultra Heat Treatment. This process kills off all microorganisms and the very short holding temperature reduces the changes in colour and lined with aluminum foil. Milk is then distributed through various outlets.
The sealed bottles are now heated for 30 to 40 minutes at temperatures ranging from 104-110°C in steam chambers calledautoclaves and then allowed to cool. Milk can also be sterilized before bottling. It is subjected to temperatures of 135-150°C for just 1 second. This is called the UHT or Ultra Heat Treatment. This process kills off all microorganisms and the very short holding temperature reduces the changes in colour and lined with aluminum foil. Milk is then distributed through various outlets.
Effect of heat on
Milk
Digestibility is
slightly improved in the heated milk as it tends to form smaller, tenderer
curds in the stomach than are formed from raw milk. Heating to higher
temperatures than those used in pasteurization effects a greater variety of
changes in milk. The tendency of milk to curdle is diminished by the use of low
or moderate temperatures. Casein is not coagulated at the usual temperatures.
It coagulates when heated at too high temperatures or for long period of time
at boiling temperature.
The coagulation of
milk protein by heat is accelerated by an increase in acidity. Heating milk brings
about an increase in acidity. The addition of acid foods to milk may also
result in coagulation.
The browning
reaction, non-enzymatic browning or Millard reaction occurs when sugars and
proteins are heated together. The prolonged heating of condensed milk in the
can results in a product of brown colour, caramel flavour and thickened
consistency.
Minerals like
calcium phosphate is precipitated by heat and sometimes gets collected at the
bottom of the pan with coagulated albumin and some of it gets entangled in the
scum on the top surface of the milk.
Skin formation is
one of the most troublesome of reactions that occurs during the heating of
milk. It may be prevented by covering the pan, by diluting the milk, or by
presence of fat floating on the surface. As the temperature is increased, a
tough scum forms, which is insoluble and can be removed from the surface. The
scum is composed of coagulated albumin with some precipitated salts and fat
globules. Scum formation can be prevented by beating the
cooked milk with a beater. The formation of scum on boiled milk is the
principal reason for the behaviour of milk in boiling over. A certain amount of
pressure develops under the scum, which later forces the scum upward and the
milk flow over the sides of the pan i.e. spill.
The flavour of milk
that has been heated to boiling temperatures or above is described as Flat.
It is due to the loss of dissolved gases, carbon dioxide and oxygen. Some
change that occurs in the protein also influences the flavour of the cooked
milk.
The layer of fat
that may form on milk that is boiled is the result of the breaking of the films
of protein that surround the fat globules in unheated milk. The breaking of the
films of emulsifying agent permits the firm coalescence of fat globules.
The scorching of
milk placed over direct heat is due in part to the film of coagulated albumin
that collects on the bottom and sides of the pan. Stirring the milk while
heating lessens the thickness of the film, but may not prevent scorching,
particularly if large quantity of milk is heated. Millard reaction is
responsible for the brown colour of the scorched milk. Heating milk over hot
water will retard or completely prevent scorching.
Acid coagulation of
milk
Acid – either that
which is formed by bacterial action in milk, or by added acid – precipitates
casein as curd. The acid curdling the milk is a desired reaction in the making
of some cheese and curd, but is undesirable in food products such as curdling
of tomato soup, fruit cream and causes the casein to precipitate.
Rennin is an enzyme present in the stomach
of man and animals which helps to clot milk during digestion. Commercially the
enzyme is available in the form of rennet tablets or extract,
which are prepared from the inner lining of the stomach of calves and lambs.
The action of
vegetable enzyme – bromelin – from pineapple also clots milk,
but later digests the clot. Other enzymes in fruits are responsible for some of
the curdling action that occurs when milk or cream and certain fruits are combined.
All fruits and vegetables contain some organic acids but not always in
sufficient concentration to cause the curdling of milk. Destroying the enzymes
before combining the fruit with the milk will prevent curdling caused by enzyme
action. Curdling of milk may occur if tannin containing foods, such as potatoes
are cooked in milk. Tannins are also present in brown sugar and in cocoa
product.
Besides enzymes,
acids and tannins, salts present in the milk, in the food combined with the
milk, or added sodium chloride may also influence coagulation of the casein. Of
the meats commonly cooked in milk, ham usually causes more coagulation than
chicken, veal or pork. The high sodium content of ham may be responsible for
the excessive curdling that occurs when cooked with milk.
Type of Milk
A. Fluid Milk
1. Whole
milk
Milk that has none of its fat removed. It generally contains 3.25% fat. This fat is not homogenized so that the milk will have cream line.
Milk that has none of its fat removed. It generally contains 3.25% fat. This fat is not homogenized so that the milk will have cream line.
2. Skimmed
Milk
This type of milk became popular because of the emphasis on low-fat diet. Cream is separated by machine. Skimmed milk resembles fresh whole milk, except that the fat content is less than 0.5%, but rest of the nutrients remains the same, except for fat soluble vitamins. It is often fortified with vitamin D and minerals. Skimmed milk is usually pasteurized and may also be homogenized.
This type of milk became popular because of the emphasis on low-fat diet. Cream is separated by machine. Skimmed milk resembles fresh whole milk, except that the fat content is less than 0.5%, but rest of the nutrients remains the same, except for fat soluble vitamins. It is often fortified with vitamin D and minerals. Skimmed milk is usually pasteurized and may also be homogenized.
3. Homogenized
Milk
It has the same composition as the whole fluid milk, but the fat content is dispersed throughout the mass through the process of halogenations. There won’t be any cream line when the milk is heated.
It has the same composition as the whole fluid milk, but the fat content is dispersed throughout the mass through the process of halogenations. There won’t be any cream line when the milk is heated.
4. Toned
Milk
Toning is done to make buffalo milk resemble in appearance and flavour to cow’s milk. It is done by dilution and addition of skimmed milk powder. 40 % of skimmed milk is added to 60% of buffalo milk. The addition of skimmed milk powder makes up for the dilution of the nutrients, the fat content remains diluted and equal to that of cow’s milk.
Toning is done to make buffalo milk resemble in appearance and flavour to cow’s milk. It is done by dilution and addition of skimmed milk powder. 40 % of skimmed milk is added to 60% of buffalo milk. The addition of skimmed milk powder makes up for the dilution of the nutrients, the fat content remains diluted and equal to that of cow’s milk.
5. Fortified
Milk
Additional nutrients such as Vitamin D may be added to milk to improve the quality.
Additional nutrients such as Vitamin D may be added to milk to improve the quality.
6. Flavoured
Milk
Addition of flavouring agents such as essences like vanilla, strawberry and masalas to improve the flavour, appearance and to add more variety.
Addition of flavouring agents such as essences like vanilla, strawberry and masalas to improve the flavour, appearance and to add more variety.
B. Concentrated Milk
1. Evaporated
Milk
This is unsweetened concentrated milk. After pasteurization. The milk is evaporated under reduced pressure in steam heated vacuum pans, till the volume has been reduced to 60%. It is then homogenized, cooled and canned.
This is unsweetened concentrated milk. After pasteurization. The milk is evaporated under reduced pressure in steam heated vacuum pans, till the volume has been reduced to 60%. It is then homogenized, cooled and canned.
2. Condensed
Milk
The term usually implies whole milk, which has been partially evaporated and to which sugar has been added. This is sweetened concentrated milk. 27% moisture remains out of 80%. It has a 62% sugar concentration. The milk is cooled very carefully, so that the crystallization of the lactose is in very fine crystals before being canned.
The term usually implies whole milk, which has been partially evaporated and to which sugar has been added. This is sweetened concentrated milk. 27% moisture remains out of 80%. It has a 62% sugar concentration. The milk is cooled very carefully, so that the crystallization of the lactose is in very fine crystals before being canned.
3. Dried
Milk or Milk Powder
In this case, the water content is removed completely and thereby the bulk is reduced. It requires no special storage facilities and is an outlet for the skimmed milk from cream and butter production. There are two processes for drying milk:
In this case, the water content is removed completely and thereby the bulk is reduced. It requires no special storage facilities and is an outlet for the skimmed milk from cream and butter production. There are two processes for drying milk:
a. Roller
Drying
The milk is usually concentrated in an evaporator until it has 97% total solids as against 11.5% in normal fluid milk. The milk is then fed into the very smooth surface of single or twin heated drums, operating at temperatures of 150°C (303°F). The water content of the milk evaporates very quickly, leaving behind a thin film of dried milk, which is then scraped off by a blade that is attached to the drums. This is then cooled before being ground into a very fine powder. It is then sieved and packed into airtight containers. Milk powder is hydroscopic and will quickly absorb moisture from the air and the powder will deteriorate, becoming stale in flavour and less soluble in reconstitution. Although roller drying is cheaper and produces a product that is practically free from bacteria owing to the severe heat treatment it receives, it does develop a cooked flavour and will not reconstitute easily. The structure of the fat globules in milk is destroyed, causing an oily layer on the surface when reconstituted in warm water.
The milk is usually concentrated in an evaporator until it has 97% total solids as against 11.5% in normal fluid milk. The milk is then fed into the very smooth surface of single or twin heated drums, operating at temperatures of 150°C (303°F). The water content of the milk evaporates very quickly, leaving behind a thin film of dried milk, which is then scraped off by a blade that is attached to the drums. This is then cooled before being ground into a very fine powder. It is then sieved and packed into airtight containers. Milk powder is hydroscopic and will quickly absorb moisture from the air and the powder will deteriorate, becoming stale in flavour and less soluble in reconstitution. Although roller drying is cheaper and produces a product that is practically free from bacteria owing to the severe heat treatment it receives, it does develop a cooked flavour and will not reconstitute easily. The structure of the fat globules in milk is destroyed, causing an oily layer on the surface when reconstituted in warm water.
b. Spray
Drying
The milk is pre-heated to 80-90°C for 10 seconds. It is homogenized and concentrated at 43°C to about 40% total solids. The milk is then atomized to a fine mist in a drying chamber containing hot air at 165°C (330°F). The very minute milk particles give off their moisture content almost instantaneously and drop to the bottom of the drying chamber as tiny grains of dried milk. The powder is removed to cool as quickly as possible, before being packed into airtight containers. This method is more expensive than Roller drying, but has 98% solubility with less pronounced flavour changes than Roller dried milk.
The milk is pre-heated to 80-90°C for 10 seconds. It is homogenized and concentrated at 43°C to about 40% total solids. The milk is then atomized to a fine mist in a drying chamber containing hot air at 165°C (330°F). The very minute milk particles give off their moisture content almost instantaneously and drop to the bottom of the drying chamber as tiny grains of dried milk. The powder is removed to cool as quickly as possible, before being packed into airtight containers. This method is more expensive than Roller drying, but has 98% solubility with less pronounced flavour changes than Roller dried milk.
c. Instant
Milk Powder
This type of powder will dissolve easily and completely when added to water, tea or coffee. The process is a modified spray-drying method in which the dried milk powder is moistened with steam to give a lumpy porous structure; the lumps of powder are being dried, cooled and then reduced to a more standard size. When added to a liquid, they quickly absorb it and dissolve completely. The cost of this type of milk powder is high and it is mainly used in hot beverages
This type of powder will dissolve easily and completely when added to water, tea or coffee. The process is a modified spray-drying method in which the dried milk powder is moistened with steam to give a lumpy porous structure; the lumps of powder are being dried, cooled and then reduced to a more standard size. When added to a liquid, they quickly absorb it and dissolve completely. The cost of this type of milk powder is high and it is mainly used in hot beverages
The concentration
of milk serves three main purposes:
1. It reduces
bulk by the reduction of the water content.
2. The heat
treatment and high sugar content in condensed milk gives the product a good
shelf life.
3. It is
convenient outlet for skimmed milk from the production of butter and cream.
Substitute milk
powder
It doesn’t contain
any milk constituent at all, but are especially processed from products such as
dried glucose, syrup and vegetable fat.
Imitation milk
Also known as Substitute
milk, it is a recent development. The products don’t contain any milk
constituent, but contain glucose syrup and vegetable fat. It has a very low
calorific value. Another substitute being promoted as a healthier alternative
to milk is Soya milk. Soya milk is much cheaper, but leaves an
unpleasant after-taste and flavour. Imitation and substitute milk are ideal for
those who are lactose intolerant i.e. allergic to milk.
C. Cultured
Milk
The process
consists of deliberately souring the milk by adding specific harmless bacteria,
which will then produce an acid and so control the growth of possible harmful
bacteria. The process originated by man’s attempts to prevent milk from being
totally unusable and develops into a variety of products, which are nutritious
and easily digestible. Cultured milk can be classified into three groups, as
listed:
1. Butter
Culture
These include butter-milk and cultured cream.
Butter-milk is a byproduct from the manufacture of butter. It is made from pasteurized skimmed milk, which is incubated with an acid producing butter culture.
Cultured cream is prepared from pasteurized single cream, which is incubated with an acid producing butter culture. It is often marketed as “fresh soured cream” to distinguish it clearly from cream, which has soured by accident or carelessness. It may be used in recipes instead of sour cream.
These include butter-milk and cultured cream.
Butter-milk is a byproduct from the manufacture of butter. It is made from pasteurized skimmed milk, which is incubated with an acid producing butter culture.
Cultured cream is prepared from pasteurized single cream, which is incubated with an acid producing butter culture. It is often marketed as “fresh soured cream” to distinguish it clearly from cream, which has soured by accident or carelessness. It may be used in recipes instead of sour cream.
2. Yogurt
Culture
These include yogurt (in many forms and flavours), curdled milk and soured milk drinks. Yogurt can be made from whole, skimmed, evaporated or dried milk or a mixture of these. Various types of yogurt are available – natural yogurt made from milk products, natural yogurt sweetened with sugar, fruit yogurt, which may be flavoured with pieces of fruits or just fruit juice or a flavouring essence.
These include yogurt (in many forms and flavours), curdled milk and soured milk drinks. Yogurt can be made from whole, skimmed, evaporated or dried milk or a mixture of these. Various types of yogurt are available – natural yogurt made from milk products, natural yogurt sweetened with sugar, fruit yogurt, which may be flavoured with pieces of fruits or just fruit juice or a flavouring essence.
3. Weak
alcoholic beverages
This group differs from the previous groups in that yeast cultures, which produce alcohol, are added, in addition to bacterial cultures. This group includes:
This group differs from the previous groups in that yeast cultures, which produce alcohol, are added, in addition to bacterial cultures. This group includes:
a. Kefir
(Poland)
It is made from whole or skimmed cow’s milk to which the kefir grain is added. The milk is incubated for three days, during which the alcohol and acid percentage increases. The finished product resembles single cream in appearance and has a lactic acid flavour.
It is made from whole or skimmed cow’s milk to which the kefir grain is added. The milk is incubated for three days, during which the alcohol and acid percentage increases. The finished product resembles single cream in appearance and has a lactic acid flavour.
b. Koumiss/Kumis
(Russia)
It was originally made from mare’s milk and is now produced from cow’s milk. Two cultures are added to milk and is incubated at 37°C for about 4-6 hours and cooled to 30°C and yeast added and incubated for 4 hours at 25°C. Matured for 3 days during which the alcoholic and acid percentage increases. The product resembles single cream in appearance, but is slightly grey in colour and has smell gas bubbles throughout, sour in taste and has a faint alcoholic smell.
It was originally made from mare’s milk and is now produced from cow’s milk. Two cultures are added to milk and is incubated at 37°C for about 4-6 hours and cooled to 30°C and yeast added and incubated for 4 hours at 25°C. Matured for 3 days during which the alcoholic and acid percentage increases. The product resembles single cream in appearance, but is slightly grey in colour and has smell gas bubbles throughout, sour in taste and has a faint alcoholic smell.
c. Whey Champagne (Poland)
This is made from clarified way with the addition of yeast and caramel. The product is of a clear, light amber colour with a slight sparkle to it and a faint caramel flavour.
This is made from clarified way with the addition of yeast and caramel. The product is of a clear, light amber colour with a slight sparkle to it and a faint caramel flavour.
d. Feliwsoka
(Poland)
It is made from buttermilk, which is fermented at 15-18°C for 8-10 hours, until the required acidity is reached. The liquid that has separated to the top is removed and sugar and yeast are added. The buttermilk is then bottled, sealed and kept at 18-20°C for 4 hours, cooled below 8°C and stored. The final product appears foamy due to carbon dioxide production and has a sweet, yeasty and refreshing taste.
It is made from buttermilk, which is fermented at 15-18°C for 8-10 hours, until the required acidity is reached. The liquid that has separated to the top is removed and sugar and yeast are added. The buttermilk is then bottled, sealed and kept at 18-20°C for 4 hours, cooled below 8°C and stored. The final product appears foamy due to carbon dioxide production and has a sweet, yeasty and refreshing taste.
Uses of Milk
1. Served as a
refreshing drink – both hot and cold.
2. Served as a
beverage with tea and coffee.
3. The main
ingredient in some sauces like Béchamel.
4. Used to
enrich dishes like soups and to give a smooth texture.
5. The main
ingredient in several desserts like ice-cream, puddings and custards.
6. The first
food for new born infants.
7. Acts as a
cooking medium for Indian sweets like Kheer or Payasams.
Storage of Milk
The rich
nutritional composition of milk makes it readily infected with micro-organisms,
which may be derived from the animal, the equipment or the people handling the
milk. Fresh milk should be purchased daily. Old and new milk should never be
mixed. Leftover milk can be easily converted into curds. Fresh milk should be
stored at refrigerated temperatures of 2°C after boiling and cooling. Milk
should never be stored near strong smelling foods such as cut onions and peeled
garlic as milk readily absorbs flavours and odour. Milk must never be exposed
to direct sunlight as riboflavin is very easily lost. UTH and
canned (evaporated and condensed) milk must be stored at slightly lower
than room temperatures. When opened, they must be refrigerated immediately and
used within two days. Dried milk must be stored in airtight containers in a
cool and dry area of the storeroom.
CHEESE