MILK FERMENTATION- PASTEURISATION AND STERILISATION

Milk represents one of the most common source of nutrients used widely in all countries and human cultures. There are many kinds of milk available depending on the type of animals used to produce the milk. However, dairy milk or cow milk represents the most popular type of milk used by man.
Milk is so nutritious that not only its ideal for human nutritional requirements but also for the calves for which nature intended it to be in the first place.
It is a sad and tragic fact that lactating cows are the ones used to produce milk which we need in volumous amounts. To do so, these cows are needed to be fertilized, and only after they give birth to calves would milk be produced. Since the cows are meant to be producing milk, I often wonder what happens to the young calves produced once the dairy cows start lactating. Will they be allowed to grow into maturity or will they be slaughtered young ending up as veals?
My apologies for the temporal distraction from the topic…. Just cannot help it!
BACTERIA LOVE MILK TOO!
Milk being nutritious will also proves to be irresistable to the bacteria. Milk is rich with proteins and various vitamins and growth factors is too good a deal to be rejected by the bacteria. Bacteria especially those that are nutritionally fastidious will grow well in milk.
This nutritional attraction for the bacteria will have serious implications for the humans that drink the milk. Not only will the humans have to compete for the milk with the bacteria but the bacteria will result in the spoilage of the milk itself by its biochemical activities. The bacteria itself will be a source of microbial pathogens and diseases.
CONSEQUENCE OF MILK MICROBIAL CONTAMINATION
One of the consequence of microbial contamination and spoilage of milk will be short shelf life of the milk.Attempts were made to solve the above problem not only due to health but economic consequences.
One of the most common ways to reduce microbial contamination of milk is either by killing or removing the microorganisms in the milk.
There are several methods to achieve this but each method will have its own advantages and limitations.
The use of heat or high temperature is commonly used in pasteurisation or sterilisation of milk.
PASTEURISATION
One of the earliest method used in industries to solve the problem is by the process of pasteuerisation. This process is named after the famous microbiologist Louis Pasteur.
In the pasteurisation process the milk is subjected to a high temperature for a period of time which will allow the killing of some of the microbes without really damaging the quality of the milk
In the Pasteurisation process the presence of microbes is reduced…. (REDUCED) and not completely sterilized! The effect of pasteurisation process will be making the milk safer and prolonged the shelf life of the milk. This is of important consequence to the milk industries as more milk can be distributed wider and more profit
It should be noted the concept of pasteurisation is relevant more in the past when refrigeration is not a common household item.
In pasteurisation we see the reduction of the microbes occurred as the consequence of heat being applied. The MAIN OBJECTIVE in pasteurisation is the reduction or destruction of the microbes in the milk.
Pasteurisation is never seen as what EFFECT the process has on the nature and composition of the milk itself and its nutritional value of the natural milk itself
Milk being dominantly protein and amino acids with vitamins and growth factors are affected by heat. Pateurisation will alter the values of the milk itself.
Heating to this temperature, but no higher, does not change the proteins in the milk or the yoghurt so the taste is not really affected.
MILK STERILISATION
The most popular alternative to milk pasteurisation now is using the ultra heat treatment. In UHT the milk is heated to at least 135°C for at least one second. UHT destroys all bacteria in the milk and makes it last much longer than ordinary pasteurised milk. How ever using UHT does cause changes to the taste of the treated milk due to the denaturing of some of the protein components in the milk.





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