Quantitative model studies on the formation of aroma-active aldehydes and acids by Strecker-type reactions

Citation
T. Hofmann et al., Quantitative model studies on the formation of aroma-active aldehydes and acids by Strecker-type reactions, J AGR FOOD, 48(2), 2000, pp. 434-440
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Agricultural Chemistry","Chemistry & Analysis
Journal title
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
ISSN journal
0021-8561 → ACNP
Volume
48
Issue
2
Year of publication
2000
Pages
434 - 440
Database
ISI
SICI code
0021-8561(200002)48:2<434:QMSOTF>2.0.ZU;2-W
Abstract
Application of aroma extract dilution analysis on the volatiles formed by r eacting glucose and L-phenylalanine (30 min, 100 degrees C) revealed the St recker aldehyde, phenylacetaldehyde (PA), and, in addition, phenylacetic ac id (PAA) as the two key odorants among the volatiles formed. Quantitative m easurements on alpha-dicarbonyl formation revealed that the 3-deoxyosone an d glyoxal were formed as the first prominent sugar degradation products, wh ereas 2-oxopropanal became predominant after similar to 4 h at 100 degrees C. Among the four alpha-dicarbonyls analyzed, 2-oxopropanal proved to be th e most effective in generating PA as well as PAA from phenylalanine, but th e reaction parameters significantly influenced the ratio of both odorants; for example, at pH 3.0 the ratio of PA to PAA was 3:1, whereas at pH 9.0 th e ratio was 1:5. Furthermore, in the presence of oxygen and copper ions the formation of the acid was further increased. 3-Deoxyosone and glucosone we re found to be effective precursors of phenylacetaldehyde, but neither was very effective in acid generation. On the basis of the results, a new oxyge n-dependent formation pathway of the Strecker reaction is proposed.