THE PRODUCTION OF CREAM

THE PRODUCTION OF CREAM

Traditionally, the milk is left to stand for about 24 hours, the cream rises and is then skimmed from the surface. The modern commercial method is much more efficient and extremely rapid. The cream is separated by centrifugal force in a mechanical separator, under very strict hygienic conditions.

The separator consists of spaced conical plates and works much like a spin-drier. As the bowl spins round at high speed, the cream, which is lighter than the milk is diverted towards the outside. The cream is then cooled to 4.5°c.

The skimmed milk is heated to a temperature of between 72°c and 80°c, to destroy any harmful bacteria. It is then cooled to less than 5°c and used to produce other milk products, for example, cottage cheese.

HEAT TREATMENT OF CREAM

Cream which has been pasteurised, sterilised, ultra-heat treated or is untreated must be described as such on the label. This is a legal requirement of the Cream Regulations 1970. Regulations also came into operation in November 1983, which include statutory specifications for heat treatment.

Pasteurisation

Pasteurisation destroys any harmful microorganisms which may be present in cream and improves keeping quality, without affecting the nutritional value or flavour of the cream. The heat-treatment is carried out by:

a)     Heating cream to at least 63°c for not less than 30 minutes; or

b)    Heating cream to at least 72°c for not less than 15 seconds; or

c)     Heating cream to any other time and temperature combination which has an equivalent effect to (a) and (b).

It is then cooled to 4.5 °c and pumped into tanks ready for packaging in bottles or cartons and sealed with metal 

foil caps.

Homogenisation

In this process the cream is forced through a tiny orifice under considerable pressure. This breaks the butter-fat globules into a smaller, uniform size and ensures an even distribution through the cream. Homogenisation thickens the cream and increases its viscosity.

Sterilisation

Sterilisation destroys any viable microorganisms and their spores. Cream to be sterilised is first homogenised, filled into the containers in which it is to be sold, hermetically sealed and sterilised by:

a)     Heating to 108°c for not less than 45 minutes; or

b)    Heating to any other time and temperature combination which has an equivalent effect to (a).

Ultra Heat Treatment

This heat treatment destroys any pathogenic or non pathogenic bacteria, but due to the short duration of the heating process, the cream retains a flavour similar to pasteurised cream. The cream is first homogenised, then heating to 132°c for one second and cooled immediately. It is then packaging in foil-lined containers.

TYPES OF FRESH CREAM

Half cream may be called ‘top of the milk’ or ‘coffee cream’. It is ideal for pouring over fruit or cereal, or used in coffee

Single cream is another pouring cream which does not have sufficient fat to whip. Its uses are as for half cream.

Whipping cream is ideal for whipping. It should whip to more than twice its original volume. It can be used for topping.

Double cream is slightly homogenised. It has a very rich texture. It will whip, but unless used for piping on gateaux/ cakes etc. The whipping texture can be improved by adding a little milk.

Double cream extra thick is heavily homogenised and so will not whip successfully. It is served with puddings, sweets and on fruit.

Double cream ‘extended life’ is usually stored in glass bottles or jars. It may be described as ‘long keeping’ or ‘extended life’ cream. This cream is heated to 82°c for 15 seconds, and then cooled. It is homogenised, filled into  bottles which are vacuum sealed and then heated in the bottle to 115°c for 12 minutes, in a similar way to pasteurisation, but the cream has a longer life, and will keep for two to three weeks in the refrigerator.

Clotted cream is a thick cream with a nutty flavour and is golden yellow in colour.

MINIMUM LEGAL FAT CONTENT (BY WEIGHT)

Clotted Cream	55%
Double Cream	48%
Whipping Cream	35%
Whipped Cream	35%
Sterilised Cream	23%
Sterilised Half Cream	12%
Single Cream	18%
Half Cream	12%

FACTORS AFFECTING THE WHIPPING OF CREAM

      I.        The fat content of cream

    II.        Availability of free protein

   III.        Temperature at which the cream is whipped

   IV.        Viscosity of the cream

    V.        The type of whisk used (a balloon whisk is recommended)

   VI.        The addition of sugar

 VII.        The size of the fat globules

It is important that all equipment used, and the room in which the cream is to be whipped, should be cool -8°c

Once the cream has been treated, attempts should be made to whip it when it is 24 hours old. This increases the viscosity of the cream and improves its whipping properties. This is known as ‘ageing the cream’.