Processing of Cream

The processing of cream depends on the purpose for which it is required. In general following processes are involved for different types of cream.

 

i. Standardization

The fat content of cream is adjusted to the desired level either by the addition of calculated quantity of water or skimmed milk. This step is referred to as standardization. The use of water or skim milk depends on the purpose for which the cream is required. If the buttermilk is to be used for drying or standardization of milk for products making or for beverage preparation the standardization is done with skim milk. The purpose for which cream is to be used and the suggestion for use of skim milk or water are indicated below in Table

Standardizing agents for cream

The cream after standardization is subjected to homogenization and appropriate thermal processing prior to packaging for retailing.

 

ii. Homogenization

Cream is an oil-in water emulsion. Therefore the cream standardized to various fat levels with skim milk must be homogenized to reduce the fat globule size and increase the stability i.e., prevent fat separation. Homogenization is a process whereby cream is forced through a narrow orifice under considerable pressure.This breaks up the fat globules to smaller size and ensures they are evenly distributed throughout the cream. By homogenization various grades of viscosity in cream products can be obtained. Usually lower pressures are used for cream than that used for milk products. Whipping cream is rarely homogenized as this process greatly reduces the whipping ability of cream. Stabilizers such as mono-glycerides are added to improve whipping ability. On the other hand, homogenization of high fat cream is utilized in the production of spoon-able whipped cream products, which are used as dessert toppings. Homogenization is employed for UHT pasteurized whipping cream in order to prevent fat separation, which increases with UHT pasteurization.

 

iii. Thermal Processing

The thermal processing of cream involves either pasteurization or sterilization. The cream could be pasteurized by either batch or continuous method. The sterilization could also be done by either of the two methods, i.e., by batch method using counter pressure autoclaves referred to as retorts or by continuous method followed by aseptic packaging. The time-temperature combination for cream is higher in comparison to milk processing. This is simply because it contains more total solids than milk. The possible time-temperature combinations are indicated below.

Batch Pasteurization - 74°C/30 minutes
Continuous Pasteurization - 85°C/25 seconds
Batch Sterilization - 115-120°C/15 minutes
UHT Processing - 135°C/1-3 seconds

As soon as the heat processing of cream is completed it is cooled to less than 10°C to avoid the growth of heat resistant micro-organisms during storage. In practice it is cooled to 4-5°C.

 

 iv. Packaging and storage

The cream after processing is packaged in suitable containers and stored at low temperature (below 5 °C). If the cream is sterilized or UHT cream it can be stored at ambient temperature.