The manufacturing process for most of these products is similar. Preparing the mix involves moving the ingredients from the storage areas to the mix preparation area, weighing, measuring, or metering them, and mixing or blending them.
Blending is the initial step for operation of the ice-cream manufacturing process. In this step, all the ingredients are added to milk at different temperatures as per the process. Good mixing is essential to the mouth feel and taste of finished ice cream. Large fat globules increase the viscosity of the mix beyond what is desirable.
Ice cream mix is pasteurized at 155°F (68.3°C) for 30 minutes or 175°F (79.4C) for 25 sec. An ice cream mix may contain various types of microorganisms, especially pathogens. Hence, it is important to pasteurize the ice-cream mix.
Ice cream mix is homogenized (2500 to 3000 psi) to decrease the milk fat globule size to form a better emulsion and contribute to a smoother, creamier ice cream.
After heating/pasteurizing, the mix is sent to the cooling section. In this section, temperature is reduced from 82° C/84° C to 6 °C. This is done to facilitate the process of ageing the icecream mix. Ageing refers to the process of holding the mix at a low temperature for a definite time before freezing.
The prepared ice cream mixture is agitated to incorporate void or air spaces and cooled down rapidly below the freezing point of water to prepare ice cream of desired characteristics. The increase in volume of ice cream due to the incorporation of air is known as the ‘% overrun’, and in commercially produced ice creams this varies from 60-100% or more.
It is followed by whipping and freezing this mix dynamically under high shear to soft, semi-frozen slurry. As a result, produced ice cream would have smooth, semi-solid foam which is solid at low temperature. It becomes softer again as the temperature increases.
The flavoring ingredients are then incorporated in this partially frozen mix. There are a large number of potential product variations, including a wide range of flavours (e.g. vanilla, chocolate or fruit flavours) and corresponding colours, and different textures that depend on the addition of additives or differences in the method of production. Only ingredients that are liquid can be added before the freezing, to make sure the mix flows properly through the freezing equipment.
It is then placed in molds for desired shaping and packaging the product. It is further subject to freezing (hardening) under static, quiescent conditions. Swept-surface freezers are used for the first freezing step, while forced convection freezers, such as air blast tunnels or rooms, or platetype conduction freezers are used for the second freezing step.
Production of ice cream
