2-Aminoacetophenone Is the Main Volatile Phase I Skatole Metabolite in Pietrain × Baden-Württemberg Hybrid Type Boars

Abstract

Skatole metabolites have been considered as putative contributors to boar taint. Recently, 2-aminoacetophenone, a volatile phase I skatole metabolite, was identified in back fat samples from boars of Pietrain × Baden-Württemberg hybrid type. This paper addresses the question of the physiological origin of the observed 2-aminoacetophenone in these pigs. Microsomal fractions from nine boars were isolated, and formation of skatole metabolites was subsequently analyzed by stable-isotope dilution analysis (SIDA) using headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS). Significant breed-related differences in phase I skatole metabolism were observed, explaining the high levels of 2-aminoacetophenone in Pietrain × Baden-Württemberg hybrid type boars.

Comparative Aroma Extract Dilution Analysis (cAEDA) of Fat from Tainted Boars, Castrated Male Pigs, and Female Pigs

“…As expected, androstenone, skatole, and indole share high OAVs in boar fat. Additionally, an important contribution to the overall aroma of boar fat is assigned to 2-aminoacetophenone in our experiments, resulting in an OAV of 30, which is consistent with our previous assumptions about the possible contribution of this compound to boar taint. , …”

“…2-Aminoacetophenone was reported to be one of seven major porcine hepatic phase I metabolites of skatole . This compound was already shown to be the perpetrator of an off-flavor in white wines, which led us to the idea that it could be involved in the origin of boar taint, too. − In this context we determined high formation rates for 2-aminoacetophenone in boars of Pietrain × Baden-Württemberg hybrid type in in vitro experiments with liver microsomes . These formation rates could serve as an explanation for back fat levels of 2-aminoacetophenone above a determined sensory threshold of 150 ng/g fat that were found recently .…”

“…Additionally, an important contribution to the overall aroma of boar fat is assigned to 2aminoacetophenone in our experiments, resulting in an OAV of 30, which is consistent with our previous assumptions about the possible contribution of this compound to boar taint. 19,20 Comparison of Three Different Fats. The results of our experiments reveal that differences in the aroma of fat of the investigated fat types are more quantitative than qualitative in origin.…”

“…Albeit androstenone and skatole have been shown to play a major role in the occurrence of boar taint, other substances are suggested as contributors to the overall aroma, because occasionally samples with low concentrations of both substances are judged as tainted by sensory panels. , The aromatic amine indole and the reduced forms of the ketone androstenone, 3-α-androstenol and 3-β-androstenol, were demonstrated to have a minor impact on the perception of boar taint . In addition, some authors propose products of lipid oxidation, for example, aldehydes, ketones, and short-chain fatty acids, and products of intestinal digestion, for example, p -cresol, as further boar taint compounds. ,, Lately, we have focused on hepatic phase I metabolites as possible contributors to boar taint, in particular, the contribution of 2-aminoacetophenone. , …”

“…7,9,10 Lately, we have focused on hepatic phase I metabolites as possible contributors to boar taint, in particular, the contribution of 2-aminoacetophenone. 19,20 Wagenberg et al searched for boar taint compounds besides androstenone and skatole by means of gas chromatography− olfactometry (GC-O). 11 Within this preliminary study several volatiles, which were extracted from fried meat of tainted and untainted boars using dynamic headspace sampling, were postulated to be associated with boar taint.…”