This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
Olives and olive oil constitute a very digestible form of fatty food, and may sometimes be eaten by consumptives in lieu of cod-liver oil. French olives gathered while young and tender are very wholesome.
Olive oil is made by crushing the fruit with stones, after which the pulp is pressed in bags. The first oil thus obtained is the best. A second oil is got by adding boiling water to the pulp residue, and pressing it again. This oil is more likely to become rancid than the first (Clark). The best oil generally obtainable is from France and Italy, but an excellent quality is manufactured in Southern California. The paler variety is preferable, but, unfortunately, it is constantly adulterated or imitated. (See also Olives.) Olive oil is eaten with salads, and is also useful for frying.
Cotton-seed oil, and to some extent poppy-seed oil, are now frequently substituted for olive oil in the preparation of various foods, and the sardines which were formerly preserved in pure olive oil are, for the most part, immersed in cotton-seed oil. This oil is not rancid, but its flavour and odour, which resemble linseed oil, are not ■ agreeable when it is eaten raw with salads or fish, and, unless extremely pure, it leaves an unpleasant after-taste in the mouth. It is composed principally of palmitin and olein. It is a harmless food.
Linseed oil is sometimes substituted for olive oil, but it is not very digestible.
Cacao butter, oil of theobroma, is a firm oil obtained from cacao seeds during the manufacture of chocolate. It easily melts at the body temperature. It is used for inunctions and for making suppositories, and sometimes as an ingredient of infant foods, such as Lacto-preparata.
Nuts, especially English walnuts, cocoanuts, hickory, pecan, and Brazil nuts, all contain a good deal of vegetable oil. (See Nuts, P- 193)
The oil of nuts which have been too long kept sometimes becomes rancid and unwholesome.
Cocoanut oil is principally used in Oriental countries.
Peanut oil is used to some extent in this country, like cotton-seed oil, mainly to adulterate or imitate olive oil, which is much more expensive.
Java almond oil may also be used for cooking.