What are MCPD esters?

3-MCPD (3-monochloropropanediol) esters are chemical food contaminants that are suspected to be carcinogenic. Europe and the US have defined limit values [OS1] (Total dosage intake: 2 µg/kg body weight for EU and US) for consumers that is why food producers demand lowest possible concentration in refined oils which means < 2ppm.

Why palm oil?

Because the 3MCPD content in palm oil is comparably high. The esters can also be found in e.g. soy, rapeseed and sunflower oil but there the content is much lower. On top, palm oil is by far the most consumed vegetable oil. Due to its many positive properties it is part of numerous processed food products. 

Diagram total production of edible oils

Do those contaminants occur naturally in palm oil?

No, they are formed during the refining process, mainly during deodorization and are not present in the crude oil.

How are they formed?

Usually, 3-MCPD esters are the result of a chemical reaction in the deodorization stage. Under the very high temperatures at this process step chloride can react with the glycerol backbone of lipids to produce 3-MCPD.

3-MCPD is formed in the refinery. Why does it affect my recovery process in the mill?

Main precursor for 3MCPD formation is chloride and it is in the plantation and the mill where the chloride gets into the CPO. If we can mitigate the chloride here, we will ultimately avoid the formation in the refinery.

What can I do to mitigate chloride in my plantation?

Minimize the use of chloride containing substances in your plantation. Sources of chloride are water, fertilizers, pesticides but also your soil. Avoid saline soils if possible.

What can I do in the oil mill to mitigate 3-MCPD?

Use chloride-free steam for sterilization, minimize the use of dilution water and process time and most importantly: wash your CPO. 

How do I wash my CPO properly?

As inorganic chloride is water soluble you can wash it out. Make sure to use chloride-free water, though and mix it with you CPO. The chloride ions now migrate from the oil into the water. Now separate water and oil again with a high-speed disc stack centrifuge. Thus, you will get rid of most of the chloride.

Crude palm oil washing

Do these measures affect my yield?

Oil losses are insignificant. However, oil quality is much better.

What can I do in the refinery to avoid the formation of 3-MCPDs?

A washing process analogue to the process in the mill can be installed prior to the physical refining. This will help to reduce the chloride content. Due to an additional degumming effect the oil quality is higher which leads to savings in bleaching earth consumption. This can be done with a simple acid degumming process.

Simple Acid Degumming

However, the most reliable option, even for the worst oil qualities, is chemical instead of physical refining.

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