Thermax chillers are used in dairies across the country for cooling during the process of milk pasteurisation. Our chillers provide chilled water to rapidly cool milk in the vat (large tank) after processing or after milking. The chilled water is pumped out of the chiller and circulated through the water jacket of the pasteuriser and then returned to the chiller.
However, not every processing operation requires a chiller. Chillers are necessary if you are using the vat as a bulk tank and need to cool the milk to storage temperature (< 45 degrees) or if you are bottling milk. Milk must also be cooled to 45 degrees before being bottled and you will need some method of chilling the milk. However, it must be noted that not many cheese manufacturers and yogurt makers require chillers because they can just run tap water through the vat to cool the milk to culturing temperature (typically 110 degrees to 85 degrees).
Milk has to be pasteurised if you want to kill the harmful bacteria without changing the milk’s nutrient value. In the modern dairy, milk is pasteurised in one of two ways:
- by using the HTST (High Temperature Short Time) process, which heats the milk to at least 72°C for 16 seconds and then cools it to 4°C or,
- by using the UHT (Ultra High Temperature) process which heats the milk to at least 135°C for not less than 2 seconds and then quickly cools it down to 2°C.
Regardless of the method used, a chilling system is going to be required. To cool down the milk most dairies are starting to use some sort of central chilling system which is not only more energy efficient and more reliable, but more accurate.
Importance of Chilling of milk
In order to keep a check on the growth of micro-organisms, milk needs to undergo chilling (rapid cooling). Once exposed to the atmosphere, microorganisms gain entry into the milk and contaminate it.
As soon as microorganisms get into the milk, they start growing rapidly because milk contains all the nutrients required for their growth, and the conditions for their growth are favourable. If the growth of microorganisms is not checked then their growth will continue and this would result into several biochemical changes which makes it unfit for consumption.
Thus, the most effectively way to control the growth of microorganisms without affecting the physio-chemical properties and nutritive value of milk is to chill it.
Lower temperatures inhibit the growth of most of the microorganisms. It should be clearly understood that chilling process does neither kills microorganisms nor it renders milk safe for human consumption. It is only a means of checking the growth of microorganisms for some time.