ice cream

1. Name: Madhu Gundagani
Roll No: 1008-20-804-011
Subject: Technology of Milk and Milk Products
Topic: Freezing and Hardening of Ice Cream

2. What is
Ice-Cream?
Ice cream is a frozen dairy
product made by suitable
blending and processing of
cream and other milk products,
together with sugar and flavour,
with or without stabilizer or
colour, and with the
incorporation of air during the
freezing process.

3. Manufacturing
Process
RECIEVING RAW MATERIALS
PREPARATION
AND MIXING OF INGREDIENTS
HOMOGENIZATION
PASTEURIZATION AGING
FREEZING
PACKAGING & LABELLING
HARDENING

4. What is Freezing of Ice-Cream?
The freezing of ice cream refers to the process in which the
liquid ice cream mixture is transformed into a solid state by
reducing its temperature below the freezing point. Freezing
determines the texture, consistency, and overall quality of the
final product.
Changes occur during Freezing
of Ice-Cream:
Crystal Formation: As the ice cream mixture cools, water
molecules within it start to form ice crystals. The size and
distribution of these crystals affect the smoothness and
creaminess of the ice cream
Incorporation of Air: Ice cream contains air, known as
overrun, which contributes to its light and fluffy texture.
During the freezing process, air is incorporated into the
mixture through agitation.
Solidification of Fats and Other Components
1.
2.
3.

5. The batch freezer consists of a cylindrical
freezing chamber with a dasher, which is a
rotating blade or paddle.
The mixture is agitated by the dasher while
being cooled, which helps incorporate air and
prevent the formation of large ice crystals.
The freezer's refrigeration system rapidly cools
the mixture, usually using a refrigerant like
ammonia or Freon, to a temperature below
freezing.
The mixture is continuously agitated until it
reaches the desired consistency, typically a
semi-solid state.
Once the desired texture is achieved, the batch
freezer stops, and the frozen ice cream is ready
for extraction.
Batch freezing is a traditional method of freezing
ice cream. It involves freezing a limited quantity of
ice cream mixture at a time. It is done at -4°C to
-3°C for 7 minutes.
1.
2.
3.
4.
5.
The ice cream mixture is pumped into a
continuous freezer, which is a long cylindrical
chamber.
Inside the freezer, the mixture encounters a
series of rotating blades or tubes that
continuously scrape or agitate the mixture.
The refrigeration system of the continuous
freezer rapidly cools the mixture, similar to the
batch freezer, to a temperature below freezing.
As the mixture moves along the freezer, it
gradually solidifies and gains a semi-solid
consistency.
The frozen ice cream is then extruded from the
continuous freezer in a continuous stream or in
desired shapes (such as bars or pints).
Continuous freezing is an automated and
continuous process used by large-scale ice cream
manufacturers. It involves freezing ice cream in a
continuous flow. It is done at -6°C to -5°C for 24
seconds.
1.
2.
3.
4.
5.
BATCH FREEZING: CONTINUOUS FREEZING:

6. WHAT IS HARDENING OF ICE-CREAM?
Hardening is a continuation of freezing process. Only part of water in ice cream mix is converted
into small ice crystals in the ice cream freezer. When ice cream is removed from freezer and put in
the packaging materials it has a semi fluid consistency not stiff enough to hold its shape. Therefore
freezing process is continued without agitation in a very low temperature room until the
temperature of ice cream reaches –18 °C or below, preferably –30°C.
HARDENING METHODS:
Hardening room: This is a low temperature cold store maintained at – 30 °C or lower with large
storing space. Also a good air circulation is maintained throughout the room for uniform cooling
effect.
Hardening tunnel: This is a hardening room constructed in the form of an insulated tunnel through
which large volume of air is discharged. The air circulated in the tunnel may be at –35 to – 40 °C and
this helps in fast hardening of ice cream. Small blast tunnel hardeners may also be located in
hardening room for faster hardening. Manufacturers of large volume of
ice cream prefer to have this type of system.
Hardening cabinet: This is a small, refrigerated cabinet maintained at –25 °C or below. It may have
two or more compartments separated from each other. Ice cream cups are tightly packed and stored
in these compartments. This unit serves as hardening and storing cabinet. This type of unit is useful
where volume of operation is low.

7. Thank You