New Insights into the Formation of Aroma-Active Strecker Aldehydes from 3-Oxazolines as Transient Intermediates
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- 作者：Michael Granvogl ; Ersan Beksan ; Peter Schieberle
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2012
- 出版时间：June 27, 2012
- 年：2012
- 卷：60
- 期：25
- 页码：6312-6322
- 全文大小：461K
- 年卷期：v.60,no.25(June 27, 2012)
- ISSN：1520-5118
文摘
2-Substituted-5-methyl-3-oxazolines, a novel class of aroma precursors that are able to release the respective Strecker aldehydes by hydrolysis, were identified. Hydrolysis can take place after the addition of water or with human saliva during mastication, respectively. 2-Isobutyl-, 2-sec-isobutyl-, 2-isopropyl, and 2-benzyl-5-methyl-3-oxazolines were synthesized and structurally identified by means of gas chromatography鈥搈ass spectrometry (GC-MS) in the electron impact mode and in the chemical ionization mode as well as by one- and two-dimensional NMR experiments. With these compounds at hand, a variety of stability experiments were performed using headspace-GC-MS or proton transfer reaction鈥揗S techniques on the basis of stable isotope dilution assays, proving the ability to release the respective Strecker aldehydes was dependent on the pH value as well as on the hydrolysis time. After the addition of water at 37 掳C, for example, >70 mol % of 3-methylbutanal or >40 mol % of phenylacetaldehyde was liberated from a solution of 2-isobutyl-5-methyl-3-oxazoline or 2-benzyl-5-methyl-3-oxazoline, respectively, after 5 min. Furthermore, the presence of 2-isobutyl-5-methyl-3-oxazoline in dark chocolate containing 70% cocoa was proven by GC-MS.