Roast effects on coffee amino acid enantiomers

Abstract The effects of roast on the amino acid enantiomers ( d - and l -) of two green coffee samples ( arabica and robusta ) were determined, by gas chromatography, on a Chirasil l -Val column. The free amino acids were present in low amounts in both green samples and destroyed to a very high degree with roast. After hydrolysis, the amino acids behaved according to their thermal stabilities: some amino acids remained unchanged whilst the more thermally sensitive were slightly reduced. Generally, the mean free amino acid racemisation value was higher than that calculated after hydrolysis, and was also higher for the robusta sample. In both cases, an increase in the racemisation value with temperature was observed, with aspartic acid being the most sensitive amino acid. The results suggested that the robusta coffee matrix is more affected by roast than the arabica . The amount of d -amino acids ingested per coffee cup does not seem to constitute a serious food safety problem.

[1]  J. Zagon,et al.  D-amino acids in organisms and food , 1994 .

[2]  Y. Tan,et al.  Detection and characterization of cellular EGR-1 binding to its recognition site. , 1993, The Journal of biological chemistry.

[3]  H. Brückner,et al.  Gas chromatographic detection of D-amino acids as common constituents of fermented foods , 1989 .

[4]  H. G. Maier,et al.  Indirect determination of the degree of roast in coffee , 1992 .

[5]  L. Trugo,et al.  A study of the effect of roasting on the chlorogenic acid composition of coffee using HPLC , 1984 .

[6]  G. Marko‐Varga,et al.  Racemization of amino acids during classical and microwave oven hydrolysis — application to aspartame and a Maillard reaction system , 2001 .

[7]  S. Casal,et al.  Development of an HPLC/Diode-Array Detector Method for Simultaneous Determination of Trigonelline, Nicotinic Acid, and Caffeine in Coffee , 1998 .

[8]  S. Casal,et al.  HPLC/diode-array applied to the thermal degradation of trigonelline, nicotinic acid and caffeine in coffee , 2000 .

[9]  H. Brückner,et al.  Chromatographic determination of L- and D-amino acids in plants , 2003, Amino Acids.

[10]  H. G. Maier,et al.  Trigonelline in coffee , 1994, Zeitschrift fur Lebensmittel-Untersuchung und -Forschung.

[11]  M. Fountoulakis,et al.  Effect of the hydrolysis method on the determination of the amino acid composition of proteins. , 1998, Journal of chromatography. A.

[12]  R. Clarke.  Roasting and Grinding , 1987 .

[13]  M. Friedman,et al.  Chemistry, nutrition, and microbiology of D-amino acids. , 1999, Journal of agricultural and food chemistry.

[14]  R. Marchelli,et al.  Occurrence of D-amino acids in food: detection by capillary gas chromatography and by reversed-phase high-performance liquid chromatography with L-phenylalaninamides as chiral selectors , 1989 .

[15]  M. Clifford.  Chemical and Physical Aspects of Green Coffee and Coffee Products , 1985 .

[16]  M. Fountoulakis,et al.  Hydrolysis and amino acid composition analysis of proteins , 1998 .

[17]  Reinhard Kuehn,et al.  Analysis of free amino acids in green coffee beans , 1994, Zeitschrift fur Lebensmittel-Untersuchung und -Forschung.

[18]  Rinantonio Viani,et al.  Espresso coffee : the chemistry of quality , 1995 .

[19]  S. Casal,et al.  Gas chromatographic quantification of amino acid enantiomers in food matrices by their N(O,S)-ethoxycarbonyl heptafluorobutyl ester derivatives. , 2000, Journal of chromatography. A.