MadSci Network: Agricultural Sciences

Re: How are corn and olive oil made?

Date: Mon Sep 28 16:35:51 1998
Posted By: R. Ted Jeo, Bio Sci Tech, St. Paul, MN
Area of science: Agricultural Sciences
ID: 906139477.Ag

How are corn and olive oil made? Well, to tell you the truth, I did not know until I did a little reserach into the subject myself and found the following.

Corn oil comes from only one part of the corn kernel, namely the germ. This is the only "living" part of the kernel, the other parts are used for food storage and life support of the emerging corn embryo. The germ contains the genetic materials for a corn plant to grow, some of which are proteins and organic substances. About 25% of the germ is oil. See the parts of a corn kernel at here.

To get oil from corn, first the corn is separated from the cob, sorted and cleaned. The corn is then soaked in warm water that softens up the kernel so it can be easily broken apart. The strachy part of the kernel is separated from the germ. The germ goes on for some spinning down and rinsing which is designed to remove excess starch. From there, the oil is extracted and refined by mechanical (press/centrifugation) and chemical (solvent) extractions. See more info about corn oil processing here or here.

It takes 1 bushel (56 lbs or 25.5 kg) of corn to make 1.6 lbs (720 g) of oil..

Olive oil, on the other hand, is very unique. It is the only oil made from a fresh fruit and the only oil that is consumable without refining. Spain is the world's largest maker of olive oil. Olive oil is obtained by cleaning the olives and then pressing them. That's it. What about those grades of olive oil that you see? Well, it has to do with the process used to make the oil as well as the acidity and the aroma/flavor.

  • Extra Virgin olive oil is oil that is pressed by purely mechanical means, once, with no other processing other than washing, centrifugation and filtering. It has an acidity of <1% (of oleic acid) and has exceptional aroma and flavor.
  • Virgin olive oil is oil that is pressed as extra virgin is, but has an acidity of 1-3 % and has good aroma and flavor.
  • Olive oil, or pure olive oil, can be the 'leftovers', that is, it can be oil that is extracted from the dregs of other pressings, and extracted with other means. It is usually blended with other grades of olive oil.

    Learn more about olive, corn and other vegetable oils used in foods here.
    Take a look at this site to learn about extractions of other oil sources.
    Hope this answers your question.

    (Any commercial reference given, whether by name, in text or by subsequent web links is NOT an endorsement of any kind by myself, my employer or the Mad Scientist Network.)

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