Lucille Benedict PhD
Meg Hausman PhD
brewing, beer, flavor, chemistry
Unexpected tastes can negatively impact consumer experience in the beer industry. One such taste, a ‘mousy’ off-flavor, is diminishing the quality of sour and wild beers throughout the brewing community. The unpleasant flavor is a result of the combined presence of three organic compounds: 6-acetyl-1,2,3,4-tetrahydropyridine (ATHP), 2-acetyl-1-pyrroline, and 2-ethyl-3,4,5,6-tetrahydropyridine. Because of its unpredictable nature, brewers must wait for the compound to disappear before distribution, costing them valuable time and revenue. The factors responsible for formation, reasons for persistence, and degradation timelines of the compounds were unknown. A method for quantification was therefore necessary to determine those characteristics, and such quantification depended upon the availability of a pure standard. In response, synthesis protocols, a GC-MS method for qualification, and a method for extraction from beer were developed for ATHP. ATHP was synthesized via a mechanism by which dihydroxyacetone reacts with proline in the presence of sodium bisulfite. The product was synthesized in low yields, so different routes of synthesis were attempted. ATHP product was highly impure as evidenced by GC-MS, so various purification techniques were employed. Extraction protocols were developed on basic profile beers that were spiked with product and progressed to naturally ‘mousy’, complex beers. The ATHP component of the uncontrolled ‘mousy’ off-flavor in was synthesized, identified, and purified.
4-19-2019 10:30 AM
Krout, Liesel, "Synthesis and Analysis of 6-acetyl-1,2,3,4-tetrahydropyridine, a Major Contributor to ‘Mousy’ Off-Flavor in Sour and Wild Beers" (2019). Thinking Matters Symposium Archive. 178.