Milk Pasteurisers Explained: HTST, Batch, and What Dairies Should Know
A milk pasteuriser heats milk to destroy harmful bacteria while protecting flavour and nutrition. This guide compares HTST and batch pasteurisers, explains how each one works, covers the controls and records dairies need, and shows what to check when buying a new or used milk pasteurizer.
Josh Bray
Nov 8, 2026
Quick Answer
A milk pasteuriser heats milk to a set temperature for a set time to destroy harmful bacteria, then cools it quickly. HTST (high temperature, short time) systems pasteurise milk in a continuous flow, and batch pasteurisers heat milk in a vat. Choose by daily volume, product range and budget, and confirm that controls, flow diversion and temperature recording meet your regulator's needs.
What Does a Milk Pasteuriser Do?
Raw milk can carry bacteria that cause illness. Pasteurisation heats the milk enough to destroy those organisms, and it keeps the milk's flavour, colour and nutritional value largely intact. The process also extends shelf life by reducing the organisms that cause spoilage.
A pasteuriser does three jobs in sequence. It heats the milk to the target temperature, it holds the milk at that temperature for the required time, and it cools the milk quickly to a safe storage temperature. Every part of the milk must receive the full treatment, so the design and control of the machine matter.
Dairies, creameries, farm processors and cheese makers all use pasteurisers. The right machine depends on how much milk you handle and what you make from it.
HTST Pasteurisers
An HTST system works in a continuous flow. Cold milk enters a plate heat exchanger, where it picks up heat from milk that has already been pasteurised. A heater brings the milk to the pasteurising temperature, and a holding tube keeps it there for the required time. A flow diversion valve checks the temperature and sends any under-heated milk back for reprocessing, and a cooling section brings the milk down to storage temperature.
The common HTST standard is 72 degrees Celsius for 15 seconds. Heat recovery between the hot and cold milk makes the process energy efficient, and the continuous flow suits large volumes.
HTST systems suit dairies that process steady volumes of milk every day, including milk for bottling, cream, yoghurt and cheese. They cost more than a small batch unit and need space for the plate heat exchanger, holding tube, balance tank and controls. Our guide to plate heat exchangers explains the heart of the system in more detail.
Batch Pasteurisers
A batch pasteuriser heats a fixed volume of milk in a jacketed vat. Hot water or steam flows through the jacket, an agitator keeps the milk moving and the operator holds the milk at temperature for the set time before cooling it down.
The traditional batch standard is 63 degrees Celsius for 30 minutes. It takes longer than HTST, but it suits small producers, farm dairies and makers of artisan cheese, who value flexibility and a lower cost of entry.
Batch units also handle small and varied runs easily. A producer can pasteurise one batch of milk for cheese in the morning and another for yoghurt in the afternoon, and the vat often doubles as the vessel for the next stage of production. The trade-off is lower throughput and more manual handling.
HTST or Batch: How to Choose
Start with volume. A small dairy that processes a few hundred litres a day often does well with a batch vat. A dairy that processes thousands of litres a day, or runs for long shifts, benefits from the efficiency and flow of an HTST line.
Product range matters as well. Cheese makers often prefer the gentle, flexible heating of a batch vat, while bottlers and large processors prefer the continuous output of HTST. Consider your growth plans too, because moving from a batch unit to an HTST line later means a bigger investment and a new layout.
| Factor | HTST pasteuriser | Batch pasteuriser |
|---|---|---|
| Typical process | 72 °C for 15 seconds | 63 °C for 30 minutes |
| Flow | Continuous | One vat at a time |
| Best for | Medium and large dairies | Farm dairies and small makers |
| Energy use | Lower, thanks to heat recovery | Higher per litre |
| Flexibility | Less, set up for steady runs | High, easy to change products |
Controls, Records and Compliance
Pasteurisation only protects consumers when it runs correctly, so controls and records matter. A good system includes accurate temperature sensors, a recorder or digital log, alarms and, for HTST, an automatic flow diversion valve. Operators check the temperature and the holding time against the requirement, and they keep the records for inspection.
Dairies must also follow food hygiene law and work to a HACCP-based food safety system. Many sites test pasteurised milk to confirm the process has worked. Talk to your local authority or the relevant food regulator early, because they can advise on approval, records and testing for your site.
Cleaning and Maintenance
Milk leaves proteins and minerals on hot surfaces, and those deposits build up quickly. A pasteuriser needs a regular cleaning routine, usually with a cleaning-in-place system that circulates detergent and sanitiser through the pipework, plates and tank. Our guide to CIP systems explains how to automate it.
Maintenance matters as well. Inspect plate gaskets and seals, check pumps and valves, and calibrate temperature sensors on a schedule. Replace worn parts before they fail, because a leak between the raw and pasteurised sides defeats the purpose of the machine.
Buying a Used Milk Pasteuriser
A used milk pasteuriser can bring pasteurisation within reach of a new or growing dairy. Inspect it with care, because hygiene and control are non-negotiable.
Check the plates, tubes and vat for pitting, cracks and repairs, and look at gaskets for wear. Test the temperature sensors, the recorder and the flow diversion valve, and confirm that the controls work and that you can calibrate them. For a batch unit, check the agitator, the jacket and the outlet valve. Ask for maintenance records and any past inspection reports, and confirm that spare parts remain available. If you plan to add homogenisation, our guide to dairy homogenisers shows how the machine fits into a line.
How Machinery Masters Can Help
Machinery Masters is a UK-based marketplace for new and used industrial equipment, with verified sellers and financing available for qualified buyers. Browse the Dairy Equipment collection to compare pasteurisers, homogenisers, separators, cheese-making equipment and more.
Tell us what you need through Start Buying and machine matches land in your inbox within minutes. If you want to spread the cost, see our financing options. Replacing a machine? Create an advert for it and generate your listing in minutes.
Frequently Asked Questions
What is the difference between HTST and batch pasteurisation?
HTST heats milk in a continuous flow at a higher temperature for a short time, while batch pasteurisation heats a vat of milk at a lower temperature for longer.
Which is better for a small dairy?
A batch pasteuriser often suits a small dairy, because it costs less and handles varied, small runs easily. Larger volumes favour an HTST system.
Do pasteurisers need temperature records?
Yes. Dairies keep temperature and time records to prove that every batch received the correct treatment, and regulators can ask to see them.
How often should I clean a milk pasteuriser?
Clean it after every production run, using a cleaning-in-place routine where possible, and inspect plates and seals on a regular schedule.
What should I check on a used milk pasteuriser?
Check the plates or vat, gaskets, temperature sensors, recorder and flow diversion valve, and ask for maintenance and inspection records.
Sources and Further Reading
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