Foodelphi.com Science of Food Engineering
Pasteurization
Definition
Objectives
Methods
LTLT
HTST
UHT
MILK PASTEURIZATION
Definition
Process of heating each and every particle of milk to 63 o C for 30 minutes or 72 o C for 15 sec (or to any other time temperature combination which is equally efficient in approved and properly operated equipment and cooling the milk to 4 o C
Pasteurization
Heat Preservation Method
Purpose (Objective)
Destruction of bacteria harmful to health (pathogenic micro organisms)
Make milk and milk products safe for human consumption
Improve the keeping quality of milk and milk products
Standards for pasteurization
A. Bacterial destruction
Most heat resistant – Mycobacterium tuberculosis
Coxiella burnetti
B.Cream line reduction
Cream line (Quality) reduces with increase in time temp combinations
C.Phosphatase inactivation
Complete destruction of phosphatase enzyme
METHODS OF PASTEURIZATION
Batch method
LT LT Method
Process vats
Holder method
Continuous method
HTST- Plate Heat Exchangers
UHT
-Steam Injection type
-Steam Infusion type
Low Temperature Long Time (LTLT) Method/Batch method
Low Temperature Long Time;
Milk heated to 63 o C for 30 minutes
Heating is indirect
Heat moves through a metal wall
Water jacketed Vat/Process vat
Double walled pressure vessel
Steam or hot water circulates for heating
Water for cooling
Outer wall is insulated to reduce heat loss
Heat exchange through the inner wall to milk
Difference between temp of heating medium and milk ΔT is kept minimum
Milk is agitated by slowly moving paddles/propellers
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