ICE CREAM MANUFACTURE
The basic steps in the manufacturing of ice cream are generally as follows:
blending of the mix ingredients
pasteurization
homogenization
aging the mix
freezing
packaging
hardening
BLENDING
The ingredients chosen, weighed and blended together to produce "ice cream mix".
Blending requires rapid agitation to incorporate powders, and often high speed blenders.
PASTEURIZATION OF MIX
Pasteurization is the biological control point in the system, designed for the destruction of
pathogenic bacteria. It also reduces the number of spoilage organisms such as psychrotrophs,
and helps to hydrate some of the components (proteins, stabilizers). Temp 69° C/30 min. 80°
C/25s
HOMOGENIZATION OF MIX
The mix is also homogenized, which forms the fat emulsion by breaking down or reducing
the size of the fat globules found in milk or cream to less than 1 µ m. Two stage
homogenization is usually preferred for ice cream mix. Clumping or clustering of the fat is
reduced thereby producing a thinner, more rapidly whipped mix. Melt-down is also improved.
Homogenization provides the following functions in ice cream manufacture:
Reduces size of fat globules
Increases surface area
Forms membrane
makes possible the use of butter, frozen cream, etc.
makes a smoother ice cream
gives a greater apparent richness and palatability
better air stability
increases resistance to melting
Compiled by- MAMTA BIST,
IHM PUSA
AGEING OF MIX
The mix is then aged for at least four hours and usually overnight. This allows time for the
fat to cool down and crystallize. It improves whipping qualities of mix and body and texture
of ice cream. Aging is performed in insulated or refrigerated storage tanks, silos, etc, at or
below 5 C.
providing time for fat crystallization, so the fat can partially coalesce;
allowing time for full protein and stabilizer hydration and a resulting slight viscosity
increase;
allowing time for membrane rearrangement and protein/emulsifier interaction, as
emulsifiers displace proteins from the fat globule surface, which allows for a reduction in
stabilization of the fat globules and enhanced partial coalescence.
FREEZING/WHIPPING OF ICE CREAM
Following mix processing, the mix is drawn into a flavour tank where any liquid flavours,
fruit purees, or colours are added. The mix then enters the dynamic freezing process which
both freezes a portion of the water and whips air into the frozen mix.
Ice cream contains a considerable quantity of air, up to half of its volume. This gives the
product its characteristic lightness. Without air, ice cream would be similar to a frozen ice
cube. The air content is termed its overrun, .As the ice cream is drawn with about half of its
water frozen, particulate matter such as fruits, nuts, candy, cookies, or whatever you like, is
added to the semi-frozen slurry which has a consistency similar tosoft-serve ice cream.
HARDENING
After the particulates have been added, the ice cream is packaged and is placed into a blast
freezer at -30° to -40° C where most of the remainder of the water is recrystallization process.
Hardening invloves static (still, quiescent) freezing of the packaged products in blast freezers.
ICE CREAM MANUFACTURE - STABILIZERS AND EMULSIFIERS
-Emulsifiers are a group of compounds in ice cream that aid in developing the appropriate fat
structure and air distribution necessary for the smooth eating and good meltdown characteristics
desired in ice cream.
Compiled by- MAMTA BIST,
IHM PUSA
-Stabilizers are a group of compounds, usually polysaccharide food gums, that are responsible
for adding viscosity to the mix and the unfrozen phase of the ice cream. This extends the shelf
life by limiting ice recrystallization during storage. Without the stabilizers, the ice cream would
become coarse and icy very quickly due to the migration of free water and the growth of existing
ice crystals.
-Stabilizers and Emulsifiers make up only a small proportion of an ice cream mix (no more than 1%) but
contribute a number of properties to the product:
• Freeze-thaw stability (prevents large ice crystals from forming during freezing)
• The thickening or gelling effect also contributes to “body” and texture (or “mouthfeel”).
• In low fat products, stabilizers act as gelling and bulking agents, replacing the body and texture normally
provided by the fat content.
• Emulsifiers are added to ensure the fat content of an ice cream mix is finely dispersed to prevent the
product taking on a “buttery” texture.
Stabilizers:
• Protein type: Gelatin, Egg white
• Gums: Guar gum, locust bean gum, xanthan gum
• Seaweed extracts: Sodium alginate, propylene glycol alginate (PGA) Carrageenan
• Cellulose Based: CMC, microcrystalline cellulose (MCC)
Emulsifiers:
• Mono-diglycerides
• Polyglycerol esters
• Sorbitan esters
LIST OF STABILIZERS
Locust Bean Gum:
soluble fibre of plant material derived from the endosperm of beans of exotic trees grown
mostly in Africa (Note: locust bean gum is a synonym for carob bean gum, the beans of
which were used centuries ago for weighing precious metals, a system still in use today,
the word carob and Karat having similar derivation)
Guar Gum:
from the endosperm of the bean of the guar bush, a member of the legume family grown
in India for centuries and now grown to a limited extent in Texas
Carboxymethyl cellulose (CMC):
Compiled by- MAMTA BIST,
IHM PUSA
derived from the bulky components, or pulp cellulose, of plant material, and chemically
derivatized to make it water soluble
Xanthan gum:
produced in culture broth media by the microorganism Xanthaomonas campestris as an
exopolysaccharide, used to a lesser extent
Sodium alginate:
an extract of seaweed, brown kelp, also used to a lesser extent
Carrageenan:
an extract of Irish Moss or other red algae, originally harvested from the coast of Ireland,
near the village of Carragheen but now most frequently obtained from Chile and the
Phillipines
Compiled by- MAMTA BIST,
IHM PUSA
