How to Process Oil Seeds
A step by step guide to processing oils of seeds, nuts, and kernels from the time of harvest to storage.

Step 1

Determine which oil-containing seed you would like to process and harvest.   This link provides a list of  seeds, nuts and kernels containing oil for extraction.  There is also a number of links to websites for particular seed types at the bottom of this page.

 

Step 2

If storage is necessary, dry material must be stored so that it remains dry.  Do not store in a moist or humid environment.

 

Step 3             

Materials must be cleaned removing stones, sand, dirt, and spoiled seeds. This can be done by screening and washing.  The previous link is to a website which explains the importance of cleaning the seeds  in preparation for oil extraction.  The seeds are sometimes cleaned before storage, and in this case they must be dried after cleaning in order to  prevent molding during storage.

 

Step 4

Remove husk or seed coat and separate seeds from chaff.  If removal cannot be done by hand, grinding the seed is an option. This links to a website describing the various methods used for seed coat removal depending on the seed being extracted for oil.

 

Step 5

Heating the seed is an option, but not necessary, although it increases efficiency of extraction and protein availability.  The previous link is to a website which explains the benefits of heating the seeds before extraction.

 

Step 6

Extract oil mechanically with an oil press, expeller, or a wooden mortar and pestle. There are many different types of extractors.  This links to a website with examples of extractors and includes contacts for companies that manufacture them. There are also different types of presses.  This links to a website showing different examples of presses depending on the yield of oil desired and the seed type.

      

    press                                       Expeller   

To the left is an example of a press and to the right is an example of an expeller.



Simplest method: Fill a cloth bag with ground seed pulp and hang the bag to drain. The free run oil will flow out and the rest must be pressed out mechanically. While this is only applicable for certain seeds, most can only be extracted mechanically. This can be done by any of the following methods: 

1.)    Place heavy rocks on the materials.

2.)    Place bags of oil seed pulp, one above another, in a box or cylinder and apply great pressure.

3.)    Create a press with any available materials, such as wood or metal, placing the seed material in the press in layers, separating each layer, by a press cloth. Slowly apply pressure, gradually increasing pressure as oil is expelled.

4.)    Create an expeller or continuous Screw Press by means of a rotating auger inside a closed barrel with one hole for oil drainage.

Methods 1 and 2:

Advantages

Disadvantages

Less labor intensive

Low oil extraction

Less materials needed

 

Cheap

 

Method 3:

Advantages

Disadvantages

Materials locally available

Labor intensive

Easy to repair

Success rate varies

Low cost

 

Easy to operate

 




   
                                   

Method 4:

Advantages

Disadvantages

Less labor than presses

Equipment cost

Higher seed extraction rate

Equipment availability

Higher proportion of oil extracted

Maintenance

 

Higher impurities


*It is important to continually clean the presses and extractors after each use in order to prevent mold from establishing. Some seeds may contain harmful components that can affect the quality and safety of the oil if bacteria is allowed to form.  Cleaning materials will depend on the type of extractor or press being used.  Make sure to use supplies that are safe and that will not be harmful to the machine. This website will explain different reasons for careful and clean processing of seeds, especially if the oil is being used for consumption, and information on possible outcomes due to cross-contamination of seeds, pest control  and  heating and storage requirements.  http://www.agindustries.org.uk/assurance/ufas/gn12.pdf.

Step 7

Allow extracted oil to stand for a few days and then remove upper layer, clarifying the oil of contaminants. Further clarification can be done using a filter cloth or by boiling the oil.

 

Step 8

Store oil in sealed, clean, dry containers. The shelf life ranges anywhere from 6 to 12 months and is increased by using colored containers in a dark box away from heat and sunlight.  This link includes the importance of proper oil storage as well as other useful information about the exraction process.


A problem that people may face when trying to extract oil from a seed is that every type of seed must be cleaned, extracted or pressed, and stored differently in order for the highest efficiency, and therefore it may be diffficult to decide which method to use.  This is why the creators of this website encourage you to experiment with these various methods and if possible provide us with feedback on the results so that we can share them with others. Some examples of specific methods for processing various seeds are shown through the links below.  Happy processing!

Other websites on this topic can be found at the following addresses:

http://journeytoforever.org/biofuel_library/oilpress.html.  A website with a step by step process for constructing extractors and presses in sunflower seed processing.

http://www.green-trust.org/2000/biofuel/sunfloweroil.htm.  Another website explaining the processes for building seed extractors and presses for sunflower seeds.  These steps can be followed for other seed types taking into consideration necessary alterations in order to account for different size and strenghts of seed husks.

http://www.webpal.org/webpal/brecovery/2farmrecovery/ftpfiles/oilseed.pdf.  A paper including information on the extraction of oils from seeds and machinery involved in the process.

http://www.kvic.org.in/v4/products_10B_vill_oil_seedcomposition.asp. A website about the oil industry methods used in Ghani.

http://www.folkecenter.dk/plant-oil/publications/efdcpos_html/!Rape_Seed_Oil_Web_3.html.  A website with examples of complete oil mills.

http://attra.ncat.org/attra-pub/oilseed.html. A website including the steps mentioned above and alternate, low cost, low labor methods for cleaning and heating the seeds.

http://www.itdg.org/docs/technical_information_service/oil_extraction.pdf.  A paper including three methods for oil extraction from seeds including the traditional methods and the importance of proper cleaning, drying, and storing of the seeds.

http://www.tinytechindia.com/oil.htm.  A website including various seed types and their oil contents with additional information on extractors, etc.

http://www.hormel.com/templates/knowledge/knowledge.asp?catitemid=42&id=569. Interesting facts about the uses of various oils from seeds.

http://www.fao.org/documents/show_cdr.asp?url_file=/DOCREP/005/Y4355E/y4355e03.htm. Palm oil extraction via the fruit and the seed.

http://www.napoleon-co.com/consumers/oo_process.htm. Olive oil seed processing methods. http://www.oliveoilsource.com/mill_and_press_facts.htm.



Web Page created by Tasha Hernandez and Dan Leep on March  2, 2005.

Last updated on March 15, 2005.

Contact Info:  tlhernan@mtu.edu.