Pasteurization and Sterilization of Milk

The pasteurization process refers to heating the product at a fixed temperature and keeping it till almost all offensive microorganisms, those that might have existed, are eliminated. The timing and temperatures help to destroy Mycobacterium tuberculosis and other spoilage, higher temperature-resistant, disease-causing, non-spore-forming pathogenic organisms are present in milk. For instance, advanced commercial processes of pasteurization involve HPP (high-pressure processing), MVH (microwave volumetric heating), and PEF (pulsed electric field) pasteurization. 

Categories of long hold pasteurizers 

1. Type of spray
2. Type of flooded
3. Type of high-velocity flooding

The essential aspect of Pasteurized milk

The main purpose of milk pasteurization is to eliminate TB germ (Mycobacterium tuberculosis). Through heating and the time process pasteurization is done with other elements for instance phosphate deactivation, cream level reduction, taste, etc. 

• The main purpose of pasteurized milk production is to eliminate pathogenic organisms that cause people health concerns. Through removing such microorganisms, the consumption of the food becomes safe.   
• Pasteurization destroys destructive organisms that make the product spoilage. This extends the lifespan of the milk.

Process of Pasteurization

There are mainly two processes that could be used in pasteurization, such as 

1. Slow pasteurization and 
2. Rapid pasteurization 

Slow pasteurization applies the pasteurization heating process for various minutes at a typical temperature of 63°C-65°C for 30 minutes timing or a temperature of 75°C for 8 – 10 minutes duration. Another process is rapid pasteurization which comprises 85°C-90°C and holds for a smaller period. 

HTST Pasteurization

This pasteurization process is done at a high temperature and for a short time. Such pasteurizers generally have a continuous flow process applying heat exchangers. Commonly, plate heat exchangers with heating, recreational heating, and cooling methods are applied.

• This pasteurization is also called flash pasteurization. 
• Here, flash pasteurization includes heating milk at a temperature of 71.7°Cover 15 seconds for destroying Coxiella burnetii, the most heat-resistant bacteria.
•  In this method, the required temperature is given to the milk uniformly. 
• This treatment is most appropriate in the constant pasteurization process.
• This pasteurized milk will store for 16 days to 21 days. 
• As it is impossible to maintain the milk at a certain temperature, it is effective to maintain a scale of temperature. For safety, the milk can be heated at a temperature of 72°C – 74°C for 15-20 seconds.

HTST pasteurization advantages  

• Constant treatment.
• Overheating is restricted and Temperature is conducted at close limitation 
• Economical compared to Vat systems because of regenerative heating.

HTST pasteurization disadvantages  

• The process is difficult.
• Non-portable system. 
• The expense of Installation is high.  

LTLT (Low-Temperature Long Time) pasteurization

• In this method, the temperatures are decreased to 63°Cover 30 minutes for pasteurization. 
• The prolonged obtaining duration changes the milk protein formation and they become suitable for preparing yogurt.
• This pasteurization is suitable for long-hold pasteurization whereas the milk is covered for better pasteurization. There are many designs of batch pasteurizers in the market that are suitable for both domestic and commercial use.

UHT Pasteurization (ULTRA HIGH TEMPERATURE) 

UHT pasteurization system involves the milk heating process at 88°C temperature for three seconds. The tools are almost similar to HTST parts along with the controlling process. However, the functioning temperature is high. The holder is smaller for short pasteurizing time. 

Advantages of UHT

• Effective milk texture due to smaller holding duration 
• Greater bacterial elimination is possible. 

Uperization (Ultra-pasteurization)

This process is also called ultra-pasteurization.  Uperization involves milk heating under a higher pressure force at a temperature of 180 to 197°C. The heating of milk conducts at 150°C for lower than one sec to hold the expected pasteurization effect.

Conclusion

Therefore, it can be concluded pasteurization is an effective treatment for human consumption. Also, pasteurization has less order of thermal treatment than sterilization, usually below water-boiling temperature. The common objective of the pasteurization process is to increase the shelf-life of the product through inactivation of all spoilage pathogenic bacteria along with vegetative displeasing microorganisms mostly. Also inhibiting and preventing the activity of microbial or enzymes. Pasteurization is integrated with various types of preservation for example concentration, chemical inhibition to become more effective.