Milk Processing: Steps Milk Goes Through Before Being Packed (Term Paper Sample)

MILK PROCESSING
The processing of raw milk takes place in milk processing plants where it is subjected to various processes to significantly extend its shelf-life thus making it marketable. The end products of milk processing include; fresh milk, UHT milk, ESL milk, sterilized milk, low fat milk, skimmed milk and condensed milk. Raw milk undergoes several processing stages and they are; pasteurization, separation, mixing, homogenization and packaging.
Heat treatment and pasteurization
Pasteurization is defined as the process of controlled treating of milk to high temperatures and then cooling it without allowing recontamination. Pasteurization is done so as to increase milk safety for the end users through the destruction of disease causing microorganisms that may be present in the milk. Pasteurization is also done to enable milk to retain its natural quality by destroying spoilage microorganisms and enzymes that causes reduced quality and shelf of milk. There are several types of pasteurization methods, depending on the amount of heat applied and the holding time. These methods include: batch (vat), continuous high temperature short time (HTST), continuous higher heat shorter time (HHST), continuous ultra-pasteurization, aseptic, ultra high temperature (UHT) and sterilization pasteurization.
Batch pasteurization is mainly applied in the production of milk, viscous products (products with more than 10% fat or added sweetener), eggnog and frozen desserts. Milk is subjected to high temperatures of 145 degrees Felsius (62.80 Celsius) for holding time of 30 minutes.
HTST (high temperature/short time) pasteurization is also used in the production of milk, viscous products, eggnog and frozen dessert mixes. Milk is subjected to high temperatures ranging between 1610-1800 Felsius for a very short period of time, 15 seconds. This process maintains milk qualities better than other aggressive processes such as UHT or aseptic processing.
Continuous higher heat shorter time (HHST), milk is subjected to high temperatures ranging between 1910F – 2120 F for a very short time of 0.01 seconds to 1 second. This method is used in the production of fresh milk only.
Continuous ultra-pasteurization is used to produce milk and cream products which are to be refrigerated for extended storage. The required temperature is 2800 F for holding time of 2 seconds.
Ultra High Temperature (UHT) pasteurization consists of sterilization process whereby the raw milk is treated to very high temperatures and then chilled continuously. The temperature ranges between 275 – 3020 F and is applied for a period of 4- 15 seconds. This process is used in the production of milk products with prolonged shelf-life that can be stored at room temperature.
Sterilization, is mainly used for the production of canned milk products which are to be stored at room temperature. The pasteurization temperature is 2400 F applied for 20 minutes.
Milk standardization (cream separation).
At this stage pasteurized milk is separated into skimmed milk and cream by the help of cream separation machines. Part of the cream is then remixed in known exact proportions in order to define fat content of the milk thus standardize it. The remaining cream is processed into dairy products such as cream, condensed milk and butter by applying appropriate technologies such as evaporation, mixing and drying.
Mixing.
At this stage milk is enriched by mixing with vitamins and mineral supplements such as calcium iron. The mixing is done and blended in batch or continuous processes in the mixing unit.
Homogenization.
Homogenization, just as the name suggest, is done so as to prevent cream from disintegrating from the rest of the milk once the milk is stored. This process is done with the help of machines known as homogenizers. The process involves pushing the milk through the machine to form tiny particles as a result fat is dispersed throughout the milk evenly.
Milk filling and packaging.
The manufacturing process is complete; milk is feed into the filling and packaging machines. Milk is then packed into different kinds of packages such as; carton, glass, PET bottles, pouches with the shelf-life printed on top. For sterilized milk aseptic technology is used i.e. packages are sterilized first before being used. After which milk is ready to be delivered to consumers.