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What is Lactoperoxidase system (LP-s)?
Why LP-s is important?
Is LP-s safe?

What is the Lactoperoxidase system (LP-s)?

Milk is consumed all over the world as a nutritious diet. (photo by Brian Dugdill)

Milk is highly nutritious food which is suitable for both children and adults as an excellent source of energy, protein, vitamins and minerals.

However, due to its rich nutritional composition, it is also ideal for microbial growth. Fresh raw milk is easily deteriorated to become unsuitable for processing and human consumption.

Scientific research has revealed that Lactoperoxidase, a naturally existing enzyme in raw milk, catalyses the chemical reaction of

thiocyanate, which is also naturally found in milk, in the presence of hydrogen peroxide. The resulting compound has a bacteriostatic effect on most bacteria and even a bactericidal effect on some bacteria e.g. Escherichia coli

This naturally occurring antibacterial system against external infectious agents catalysed by the lactoperoxidase is called Lactoperoxidase system (LP-s) and can be found in other body fluids such as tears, saliva and gastric juice. (See FAQ for details)


LP-s protects milk from microbial contamination under high ambient temperature

More than 30 years ago, a group of Swedish scientists began to investigate this natural antibacterial system and its role in raw milk preservation. 

There are three components required for the activation of the LP-s; the enzyme lactoperoxidase which is abundant in raw milk; thiocyanate and hydrogen peroxide which are naturally present only at low concentrations. By adding an appropriate amount of thiocyanate and hydrogen peroxide, the LP-s 


can be reactivated in raw milk to inhibit bacterial growth. The result is that raw milk can be kept for 7-8 hours under ambient temperature in tropical countries (30 degree Celsius) without spoiling/going sour.(See the procedure for LP-s activation)

Why is LP-s important?

In natural circumstances, milk is consumed mainly by suckling infants whose immune system is undeveloped and consequently are highly susceptible to infectious agents. in these situations, LP-s protects the stomach and intestine of suckling infants against bacterial infections.

LP-s increases opportunities to access the urban market. (photo by Brian Dugdill, Jurjen Draayer)

However, the LP-s loses its effect in raw milk within 2 hours after being drawn from the udder. Growth of microorganisms then begins. A safe and effective system of raw milk preservation is therefore required by the dairy sector. Preservation should not adversely affect the nutritional characteristics of raw milk. Refrigeration is currently recognised as the preferred milk preservation method.

However, as many developing countries often cannot afford to provide reliable refrigeration due to limited infrastructure, they cannot supply sufficient fresh milk for drinking and as raw material for dairy products.

The LP-s addresses this limitation. The application of LP-s for raw milk preservation basically requires no complicated  techniques, energy consuming facilities or heavy equipment.

All that is needed is pre-packed activators, namely, thiocyanate


and a source of hydrogen peroxide (sodium percarbonate is commonly used). The cost of activators is extremely low. (less than 1 US$ cent per litre of milk treated) The LP-s application is therefore ideal for developing countries and enables dairy producers in remote areas to transport their raw milk to urban markets and milk processing units. This will result in increased income for producers and at the same time, increased safety, quality and quantity of milk available for consumers. (See FAQ for more information)
Is LP-s safe?

Although the LP-s was discovered more than 30 years ago, the safety of the system has been carefully and rigorously examined. 

In 1991, following more than 15 years of thorough field experiments on toxicity carried out by experts, the Codex Alimentarius Commission, the international authority on food standards, approved the LP-s as a safe and effective method for raw milk preservation when used according to their Guideline (Refer to FAQ for more detailed information

The LP-s is therefore globally approved as safe for application in raw milk preservation.

LP-s is a safe and effective method for milk preservation. (photo by Jurjen Draayer)