What Is Milk Pasteurization? Raw Milk, Boiling and Packet Milk Explained

Quick answer: Milk pasteurization heats milk to a specified temperature for a specified time, then cools it promptly. The process substantially reduces harmful microorganisms; it does not make ordinary pasteurized milk sterile. Properly handled pasteurized milk still needs refrigeration. Raw or unpasteurized milk needs appropriate heat treatment before drinking. If your question is whether to boil a sealed packet of milk again, the answer depends on what the label says and how the milk has been stored.

How does milk pasteurization work?

A dairy heats every part of the milk for a defined time, then cools it quickly. Two common approaches are:

These are examples of established industrial processes, not instructions to pasteurize milk by guessing the temperature on a kitchen stove. The exact applicable standard and validated equipment matter. The aim is to reduce disease-causing microorganisms while limiting changes to the milk. Some microorganisms can survive or enter milk later through poor handling, which is why refrigeration and clean packaging still matter.

Why is milk pasteurized?

Raw milk can carry harmful microorganisms even when the dairy farm looks clean and the cows appear healthy. Good animal care, clean containers and prompt chilling help reduce contamination, but cannot prove that a particular serving of raw milk is free from pathogens. Pasteurization adds a controlled safety step before milk is sold or consumed.

Pasteurization also reduces many organisms that cause spoilage. It does not make a damaged, opened or badly stored packet safe indefinitely. Use the storage instructions and date on the particular pack rather than a universal number of days.

Raw, pasteurized, boiled and UHT milk: what is the difference?

Homogenized describes a different process: breaking up fat globules so cream separates less readily. It does not mean the milk has been pasteurized. Read the label for both terms.

Do you need to boil pasteurized packet milk?

A properly sealed, correctly refrigerated packet labelled “pasteurized” has already received a validated heat treatment. Boiling is not what makes it pasteurized. Read the brand's instructions, check the use-by date and keep the cold chain intact. You can heat the milk for tea, a recipe or personal preference, but repeated prolonged boiling is not a substitute for correct storage.

There is a practical qualification in India: you may not know whether a packet stayed cold during transport or after purchase. If the packet is leaking, swollen, smells off, has been left warm for an unknown period or is past its date, do not rely on boiling to rescue it; discard it. If the label gives specific preparation instructions, follow them.

For raw or unpasteurized milk, FSSAI's household guidance says to boil it before use. Do not copy the 72°C-for-15-seconds industrial figure as a casual home method without a suitable thermometer, agitation, immediate cooling and clean handling.

Does pasteurization remove all bacteria?

No. Pasteurization is designed to greatly reduce relevant pathogens under specified conditions; it is not sterilization. Ordinary pasteurized milk can spoil, particularly when temperature control fails or contamination occurs after opening. This is why a sealed pasteurized pouch belongs in the refrigerator and why opened milk should be handled with clean utensils.

UHT milk follows a different high-temperature process and aseptic packaging. Its unopened storage instructions can therefore differ from those of ordinary refrigerated pasteurized milk. Once opened, follow the pack's refrigeration and use instructions.

Does pasteurization destroy milk's nutrition or change lactose?

The broad claim that pasteurization “removes all nutrients” is false. Milk remains a source of its major nutrients after pasteurization. Heating may affect some heat-sensitive components, but that does not establish a meaningful health advantage for drinking raw milk. Public health authorities find the safety risks of raw milk clear and do not support claims that raw milk is generally healthier.

Pasteurization does not remove lactose or make ordinary milk lactose-free. People who avoid milk because of lactose intolerance or milk-protein allergy should not assume raw milk solves either problem.

Can pasteurized milk be used to make curd or ghee?

Yes, appropriately handled milk can be used to set curd. Milk is heated or prepared according to the method, cooled to a suitable culture temperature and inoculated with starter. The curd can then be churned into butter and the butter cooked into ghee. Pasteurization is a milk safety process; Bilona describes the curd-to-butter churning route. They answer different questions.

At Gaurya Farms, our Gir cow Bilona process runs milk → curd → churned makkhan → slow-cooked ghee. Fresh milk is boiled and cooled, then set into curd using a little homemade curd from the previous batch. This is traditional boiling as part of curd-setting, not commercial pasteurization. To see the full method, read our Bilona ghee guide.

Four claims worth checking before you share advice about milk

The practical takeaway

If you buy packet milk, read whether it is pasteurized or UHT, follow the label and protect its storage conditions. If you obtain unpasteurized milk, heat it appropriately before use. Pasteurization lowers microbial risk; it does not replace clean handling. For ghee buyers, the relevant next question is how the dairy handles milk and documents each stage before curd, butter and ghee are made.

Sources

• National Dairy Development Board, Milk processing and pasteurization overview
• Bureau of Indian Standards, Packaged Pasteurized Milk
• US Centers for Disease Control and Prevention, Raw Milk
• FSSAI, Food Safety at Home
• US Food and Drug Administration, Raw Milk Questions & Answers and Raw Milk Misconceptions