Free fatty acids
| Comparison of fats and oils (= triglycerides , above) with selected free fatty acids (below) |
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 A triglyceride with three different chemically bound (esterified) fatty acids |
 Free fatty acids (examples) |
| The fatty acid residues are marked in blue , green and red . |
In food chemistry , free fatty acids are fatty acids that are present in fatty foods in addition to the fatty acids bound as esters . Free fatty acids are undesirable components in fats and oils that are used as food (= carboxylic acids that are not chemically bound as esters of glycerine ) and have an adverse effect on their quality. So is z. For example, in the case of quality ratings such as “extra virgin ” or “ virgin ” for olive oil, the permissible content of free fatty acids is decisively limited. The so-called lampante oil is an olive oil obtained by cold pressing , but it is not approved for human consumption due to its high content of free fatty acids.
rating
The higher the free fatty acid content, the lower the quality of the food. The determined content of free fatty acids (e.g. oleic acid , linolenic acid ) provides information on quality-reducing, thermally stressful preparation, decomposition processes or pretreatment. Unrefined natural oils have an acid number <10, while refined (purified) oils have an acid number <0.2.
Analytical determination
The acid number (AN) is a chemical quantity used to characterize acidic components in fats or oils. It describes the mass of potassium hydroxide (in mg ) that is necessary to neutralize the free fatty acids contained in 1 g of fat . However are not as acylglycerols (= fatty acid ester) chemically bound acids detected using, as the saponification value .
Individual evidence
- ^ Siegfried Hauptmann : Organic Chemistry , 2nd revised edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig, 1985, p. 654, ISBN 3-342-00280-8 .
- ↑ Otto-Albrecht Neumüller (Ed.): Römpps Chemie-Lexikon. Volume 5: Pl-S. 8th revised and expanded edition. Franckh'sche Verlagshandlung, Stuttgart 1987, ISBN 3-440-04515-3 , p. 3648.