2.7.4. Quantification of SCFA
For the quantification of short-chain fatty acids (SCFA), fecal samples were divided in two aliquots, one for the lyophilization, and the second for a direct measure of the molecules of interest in order to obtain the dry weight-normalized absolute concentration. SCFA (acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, isobutyric acid, isovaleric acid, and isocaproic acid) were measured on the second aliquot of test material via a gas chromatography–flame ionization detector (GC-FID) method as described by De Weirdt et al. [