Relevance of Oxygen for the Formation of Strecker Aldehydes during Beer Production and Storage

Abstract

Off-flavor in beer is often associated with the appearance of staling aldehydes. In this study, the factors amino acid concentration, carbohydrate concentration, Fe concentration, and oxygen concentration were investigated in terms of their effect on the formation of carbonyl compounds during storage using response surface methodology. From all factors tested, only amino acid concentration and oxygen concentration promoted Strecker aldehyde formation during storage while all other carbonyls measured were unaffected. A mixture of glucose/xylose, representing carbohydrate sources, as well as Fe concentration were insignificant factors; though, carbohydrate additions exhibited a significant role for the formation of 2-furfural. De novo formation of phenylacetaldehyde from phenylalanine during beer storage was observed using labeling experiments and a linear relationship between Strecker aldehydes formed and total packaged oxygen was identified. Capping beers with oxygen barrier crown corks and addition of 10 mg/L EDTA to beers effectively diminished Strecker aldehyde formation. Oxygen was additionally shown to significantly promote Strecker aldehyde formation during sweet wort production. A pathway for the reactive oxygen species-induced degradation of amino acids yielding Strecker aldehydes was proposed and was further scrutinized in buffered model solutions. The insignificant role of Fe in the response surface experiments is discussed.

Technological influence on sensory stability and antioxidant activity of beers measured by ORAC and FRAP

“…However, the potential of amino acids as precursors for aged flavor compounds has to be taken into account when evaluating their potential as antioxidants . The oxidative degradation of amino acids to the respective Strecker aldehydes was described in a recent study . The Strecker degradation product benzaldehyde is formed from phenyl alanine and plays a role in the stale flavor of beer .…”

“…The stale beer flavor is characterized by the appearance of sweet, cardboard, and bread‐like flavor notes . The overall stale flavor of beer is caused by a number of different compounds, but the vital role of staling aldehydes was emphasized by a number of studies . Staling aldehydes arise from the oxidation of fatty acids, the Strecker degradation of amino acids, the release of bound aldehydes during beer storage, the Maillard reaction, melanoidin catalyzed oxidation of higher alcohols, and the degradation of bitter acids .…”

“…35 The overall stale flavor of beer is caused by a number of different compounds, but the vital role of staling aldehydes was emphasized by a number of studies. [35][36][37] Staling aldehydes arise from the oxidation of fatty acids, the Strecker degradation of amino acids, the release of bound aldehydes during beer storage, the Maillard reaction, melanoidin catalyzed oxidation of higher alcohols, and the degradation of bitter acids. 35 The degradation of bitter iso--acids was described as an important analytical marker for oxidative beer aging by a number of authors.…”

The synthesis of two long-chain N-hydroxy amino coumarin compounds and their applications in the analysis of aldehydes

“…Then under alkaline bromination condition via retro-Reformatsky fragmentation, 39 the tertiary alcohol was converted efficiently into a,a,u-tribromo-b-ketoester (4, 95.3% yield). Compound 4 was reduced using Cu-Zn alloy in saturated ammonium chloride methanol solution at [10][11][12][13][14][15] C to afford compound 5 (64.4% yield).…”

“…2,5,10,12 The existences and concentrations of these furfuraldehydes are relevant to food safety and avor, which makes the detection and analysis of them quite important. In this study, we focused on the analysis of them via derivatization reaction with 1a and 1b.…”