1. What is Lactoperoxidase?
Lactoperoxidase is an enzyme, which is naturally present in fresh raw milk. Bovine milk contains about 30mg/l of Lactoperoxidase and the concentration is fairly constant throughout the lactation. Lactoperoxidase has no antibacterial effect on its own but has the ability to oxidise the thiocyanate ion (SCN-) in the presence of hydrogen peroxide (H2O2) (these components also exist naturally in tears, saliva, and gastric juices). The resulting chemical compound has an antibacterial effect in fresh raw milk. Against some species of normal gut flora such as streptococci and lactobacilli, the resulting compound has a bacteriostatic effect (inhibiting bacterial growth) while it has bactericidal effect (killing bacteria) against some gram-negative bacteria, i.e. Escherichia coli, pseudomonads.
2. What is the Lactoperoxidase system and how does it work?
The Lactoperoxidase system (LP-s) consists of the production of an antibacterial compound from the thiocyanate ion catalysed by Lactoperoxidase in the presence of hydrogen peroxide. This antibacterial system is naturally found in various body fluids including tears, saliva and gastric juice. The two essential components for the system, namely thiocyanate and hydrogen peroxide, are naturally present in milk in varying concentrations, depending on the feed given and on the species/breed of animal.
In drawn milk the antibacterial activity is quite weak and lasts for up to two hours because the milk contains only suboptimal levels of the thiocyanate ion and hydrogen peroxide.
The method of reactivation of the LP-s in milk is to add about 10 parts per million (PPM) of thiocyanate (preferably in liquid form) to the raw milk to increase the overall level to 15 PPM (circa 5 PPM naturally present). The solution is thoroughly mixed for 30 seconds and then an equimolar amount (8.5 PPM) of hydrogen peroxide is added (generally in the form of a granulated sodium carbonate peroxyhydrate).
This treatment reactivates the antibacterial effect of the LP-s in the raw milk and extends the shelf life of raw milk under tropical conditions for a further 7 to 8 hrs. This means that producers can transport their milk to the collection point where it is treated with LP-s and can then be transported by whatever means are available (e.g., handcarried, on bicycle, pack animal or motorised transport) for 7 to 8 hours, to a processing centre, thereby significantly increasing the income generated at farm and producer group level.
The LP-s treatment does not function as an end product treatment. It is a processing aid, which enhances the naturally occurring antibacterial system in raw milk. It is therefore essential that the quality of the raw milk is good and thus training on milk production hygiene is complementary to the effective application of the Lactoperoxidase system of milk preservation.
3. Is it safe for human and animal health?
15 years of field experiments in developed and developing countries were conducted and assessed by theFAO/WHO Joint Experts Committee on Food Additives (JECFA). Upon completion of these substantial and in-depth studies a guideline for the use of an alternative milk preservation method based on the activation of the natural enzymatic antibacterial complex in milk (Lactoperoxidase system) was approved by the FAO/WHO Expert Committee on Food Additives in 1989 and by the Codex Alimentarius Commission in 1991 as being safe for use.
The lactoperoxidase system is a natural component of saliva and gastric juice in humans and consequently non-toxic when used according to the Guidelines of the Codex Alimentarius Commission ( SeeGuidelines for the Preservation of Raw Milk by Use of the Lactoperoxidase System (CAC/GL 13-1991)).
Additional sources of information include the Thirty fifth Report of the Joint FAO/WHO Committee on Food Additives on "Evaluation of certain food additives and contaminants", Technical Report Series 789, WHO, 1990.
There is no effect on lactating animals as the treatment is carried out only after the milk has been drawn from the teat.
4. Why is FAO promoting the LP-s?
Milk represents one of the fastest income returns for small-scale livestock keepers. It is a key element for household food security. The generation of surplus milk brings income to the women and children who are usually in charge of taking care the milk-producing animals such as goats, sheep and cows. Milk can frequently generate the only regular income for rural families and is therefore essential for their survival. In remote areas small-scale milk producers face a major problem in accessing distant markets where there is a huge demand for fresh, good quality milk. Milk can usually be transported unrefrigerated for up to 20 km but after a certain period will begin to deteriorate. Souring sets in and the milk quickly becomes useless.
The Codex Guideline states that:
"this method should be utilised when refrigeration of the raw milk is not feasible" and should be used "when technical, economical and/or practical reasons do not allow the use of cooling facilities for maintaining the quality of raw milk. Use of the LP-s system in areas which lack an adequate infrastructure for collection of liquid milk, would ensure the production of milk as a safe and wholesome food, which would otherwise be virtually impossible".
In countries with an advanced dairy industry, cooling safeguards the bacterial quality of the raw milk and prevents spoilage. However cooling is rarely an applicable preservation technique for small-scale producers from milk production areas of developing countries due to the absence of reliable electrical supply or economic constraints.
The application of the LP-s is cheap, easy, effective and safe to use and readily applicable in developing countries with a minimum of training requirements. It can and will expand current and potential milk collection areas, which are today limited by lack of dairy infrastructure e.g., access roads and electricity.
A greatly increased marketing opportunity now exists for the women smallholders who generally have the responsibility for marketing of surplus milk due to the following reasons:
- many developing countries are privatising their national dairy industry and trying to reduce the importation of powder milk and butter oil for recombined milk.
- many small milk processing industries have emerged and are trying to develop their milk collection system
- the demand for fresh milk by the urban population is growing very fast.
The only limiting factor is the availability of a safe, cheap and easy-to-use system of milk preservation. With a cheap method of preservation of milk from farm to the dairy, many families can substantially increase their household income increase in a short period of time.
5. Can it be used on all types of milk?
Although the Codex Guideline refers to "raw milk (bovine and buffalo)", the LP-s has also been shown to be effective in the preservation of other types of milk including camelids. Additional research across a broader number of lactating species is ongoing and we expect that other species will be included in the guideline in the coming years.
6. Does it affect the further processing of milk?
One of the key advantages to the system is the self-limiting nature of the time-temperature effect of Lactoperoxidase. As described in the Codex Alimentarius Commission (CAC) guideline, the effect is limited to 7-8 hrs at an ambient temperature of 30C. As always, milk to be consumed fresh should be pasteurised. ( Refer toThe WHO Golden Rules for Safe Food Preparation)
Raw milk which has been treated with LP-s can be used for further processing. It is however important to bear in mind the time- temperature relationship of the activity of the enzyme Lactoperoxidase as outlined in the guideline. Recent field trials carried out in Ghana indicated that the product quality was higher in LP-s treated milk.
7. Does it improve low hygienic quality milk?
The overall effect of the LP-s is bacteriostatic in fresh raw milk. It is important that the system is applied/reactivated within two hours of milking to have full effect before there is a bloom of bacterial activity in the raw milk. Recent scientific research also indicates that the LP-s also has a slight destructive effect on Escherichia Coli. The system cannot improve the bacterial quality of milk but maintains the bacterial quality of milk to that of the application.
8. Who manufactures or distributes the activators?
At the second annual Meeting of the Global Lactoperoxidase Group of Experts in 1999, a list of known manufacturers and distributors was prepared as an annex to the proceedings and is reproduced below with known manufacturers listed in alphabetical order.
DeLaval Export AB
Producer for DeLaval: Solip Biotech AB
9. Can anyone use the system?
As with any chemical substances these chemicals should be used by trained personnel only. Normal precautions, such as keeping the activators out of the reach of children and storing in a secure location, should also be taken. The personnel at the milk collection or bulking point should be responsible for the correct and effective treatment of the milk. The milk plant or processor should be responsible for controlling the use of the activators and ensuring that the system is used as intended.
FAO recommends the licensing of the system by a recognised responsible body in the country who are then responsible for the safe and correct utilisation of the activators as outlined in the CAC guideline.
10. What is the cost of LP-s treatment per litre of milk?
The cost of LP-s treatment of raw milk is ca. 1US cent per litre of milk. The benefit will be market access due to safe and effective milk preservation. With the uptake of the system household level income from dairying can rise by an estimated 40% due to reduced postharvest losses and increased production.
11. Who are the main beneficiaries of the application of the system?
The main beneficiaries will be rural small-scale women farmers who generally manage the dairy animals. They will have an increased opportunity to market their surplus milk to the urban centres and also to reduce milk losses. This will result in a substantial increase in cash income for the household.
Secondary beneficiaries will include the processors who will have to cope with a minimum estimated increase of 40% in production of milk available for processing. The penultimate beneficiaries will be the consumers who will have improved access to safe, quality milk.
12. What do national governments need to do to facilitate the uptake or adoption of the system?
The main limitation in the uptake and adoption of the LP-s is the lack of knowledge on the existence and application of the system. Dairy industry concerns that are aware of the system tend safeguard the spread of the knowledge on the system to themselves for commercial reasons. The groups who have the greatest need of the system are small-scale dairy groups and organisations who have difficulty in collecting available milk due to lack of infrastructure.
National governments therefore need to provide full information on the system and its application. Legislative reform or adoption of the Codex guideline may be required to legalise the utilisation of the system in some countries.