Pectin manufacture comprises three to four essential steps:

1. Extraction from the plant material.

2. Purification of the liquid extract.

3. Isolation of pectin from the solution, and - if low ester (LM) pectin is the end product desired:

4. De-esterification of the high ester (HM) pectin.

The extraction of pectin is made with hot acidified water. Quantity and quality of pectin from the specific raw material to a great extent depend on proper selection and control of extraction conditions. The extract is clarified by centrifugation and a number of filtrations, the last step being a polishing filtration to ensure complete transparency in application.

Precipitation of pectin from solution may either be done with alcohol from a concentrated (2-4%) pectin solution or with an aluminum salt from a diluted (0.3-0.5%) pectin solution. When pectin is isolated as aluminum pectinate, precipitation must be followed by washing with acidified alcohol to convert the aluminum pectinate to the acid form and subsequent neutralization with slightly alkaline alcohol.

The pectin obtained by these processes is high ester pectin. This type of pectin only forms gels above a soluble solids of approx. 55%.

Low ester pectin - which forms gels in the presence of calcium ions irrespective of soluble solids - is obtained by a controlled de-esterification of high ester pectin at either acidic or alkaline conditions. If ammonia is used to de-esterify the pectin, some amide groups are introduced into the molecule and a so-called amidated pectin is obtained.

The manufacturing processes are in principle simple unit operations, but much know-how is accumulated in the practical execution of the processes. The flow sheet below gives a general description of the process used by CP Kelco ApS.