At it’s most basic level a fat molecule (triglyceride) is made up of individual fatty acids with a number unique carbon chains. The carbon chain of individual fatty acids can range from 2 to 28 carbons.
Most sources group all known fatty acids into the following basic categories:
- Short chain (fewer then 6 carbons)
- Medium chain (6-12 carbons)
- Long chain (13 to 21 carbons)
- Very long chain (more then 21 carbons)
As strange as it may sound, the main component of vinegar (acetic acid) is technically considered a short chain fatty acid. And in fact, it is the fatty acid with the shortest carbon chain found in nature.
Fats and oils are actually triglycerides. A triglyceride, is combination of three fatty acids bonded together by a glycerol (more commonly known as glycerin).
On their own, short and medium-chained free fatty acids (not in their triglyceride form) can be quite odorous.
The best example of this are dairy products, such as butter or cheese, that give off a strong odor. In these cases, single short chain fatty acids (butyric acid) become liberated from their glycerol bond and the fats begin to give off strong odors.
Accordingly, caprylic acid (as a free fatty acid) can give off quite an strong odor. However, when the fatty acids are bonded together with glycerol (through esterfication) the resulting caprylic acid triglycerides do not produce any strong odors.
In summary, the level of odor that an oil produces appears to be directly proportional to the amount of free fatty acids present (source).
Powder forms of caprylic acid are actually most common in the form of fatty acid salts. For example, magnesium caprylate, calcium caprylate, or zinc caprylate are the forms of caprylic acid most commonly found in nutritional supplements.