Journal of Agricultural and Food Chemistry
Article
was performed by means of SPME instead of SBSE. Therefore,
the results obtained at 130 °C in this experiment are not exactly
the same as those presented in Table 4. At 100 °C, no flavor
compounds were detected. At 130 °C, it was confirmed that
pyrazines were produced more in the case of diglycine as
compared to glycine. However, increasing the reaction
temperature indeed changed the flavor profiles. At 150 °C,
pyrazine production from the reaction with glycine was already
higher than from the reaction with diglycine. As was reported
by Oh et al.10 and Lu et al.,11 the production of furans and
furfurals became more important when diglycine was reacted at
this temperature. The difference between pyrazine production,
on the one hand, and furan and furfural production, on the
other hand, became even more pronounced at 180 °C. These
experiments clearly explain the origin of the differences
between literature data and our results and illustrate the
importance of choosing an appropriate reaction temperature.
With regard to the tripeptides tested, it was already
mentioned before that the production of pyrazines was lower
than from dipeptides. In addition, no clear trend could be
found for the differences in pyrazine production from
tripeptides and glucose, on the one hand, and from free
amino acids and glucose, on the other hand. However, with
methylglyoxal, all tripeptides produced higher amounts of
pyrazines than the corresponding free amino acids. As in the
case of LeuGly, ValGly, and ValLys, this suggests that especially
the early phase of the Maillard reaction is slower for tripeptide
LysGlyGly.
compounds from peptides should be taken into account. In
addition, hydrolysis of the peptide bond of both di- and
tripeptides was minimal during thermal treatment of 2 h at 130
°C.
AUTHOR INFORMATION
■
Corresponding Author
51. Fax: 00 32 9 264 62 43.
Funding
We are indebted to the Research Foundation Flanders (FWO-
Vlaanderen) for an Aspirant fellowship to F.V.L. and for a
postdoctoral fellowship to A.A.
Notes
The authors declare no competing financial interest.
REFERENCES
■
(1) Nursten, H. The Maillard Reaction. Chemistry, Biochemistry and
Implications; The Royal Society of Chemistry: Cambridge, U.K., 2005;
p 214.
(2) Belitz, H.-D.; Grosch, W.; Schieberle, P. Food Chemistry, 4th ed.;
Springer-Verlag: Heidelberg, Germany, 2009; p 1070.
(3) Hartmann, R.; Meisel, H. Food-derived peptides with biological
activity: from research to food applications. Curr. Opin. Biotechnol.
2007, 18, 163−169.
(4) Minkiewicz, P.; Dziuba, J.; Darewicz, M.; Iwaniak, A.; Dziuba, M.;
Nalecz, D. Food peptidomics. Food Technol. Biotechnol. 2008, 46, 1−
10.
For all reactions with dipeptides or tripeptides, the
production of amino acid specific pyrazines was low. The
mechanism that leads to the production of the amino acid
specific pyrazines involves the reaction between the inter-
mediate dihydropyrazine, which is formed by the condensation
reaction of two α-aminocarbonyl compounds, and the Strecker
aldehyde of the specific amino acid.17 However, in the case of
peptides, typical Strecker degradation involving decarboxylation
followed by hydrolysis of the imine is not possible due to the
absence of the free carboxyl group. Hydrolysis of the peptide
bond, resulting in the liberation of the free amino acids, should
occur to produce the Strecker aldehyde. Therefore, the limited
amounts of amino acid specific pyrazines in the case of the
dipeptides and tripeptides studied suggest only minimal
hydrolysis of the peptide bond during these model reactions.
In conclusion, the formation of pyrazines from Maillard
model systems containing di- and tripeptides was studied.
Pyrazines are known to contribute significantly to the unique
roasted aroma of many heated food products. It was shown that
most dipeptides produced very high amounts of pyrazines,
especially 2,5(6)-dimethylpyrazine and trimethylpyrazine. This
pyrazine production was higher than in the case of reactions of
glucose with free amino acids or tripeptides. Probably, catalysis
of the Amadori rearrangement in the dipeptide/sugar adduct
causes this observation. However, peptides with valine, leucine,
or proline at the N-terminus behaved differently. Therefore, it
seems that the structure of the N-terminal amino acid is
determinative for the overall pyrazine production. In contrast to
the production of substituted pyrazines, unsubstituted pyrazine
was always produced more in the case of free amino acids. No
satisfying explanation could be found for this observation, but it
is clear that different mechanisms must be responsible for the
formation of unsubstituted pyrazine, on the one hand, and
substituted pyrazines, on the other hand. These results indicate
that for heat-treated food, also the production of flavor
(5) Van Lancker, F.; Adams, A.; De Kimpe, N. Chemical
modifications of peptides and their impact on food properties.
Chem. Rev. 2011, DOI: 10.1021/cr200032j.
(6) Zhang, Y. G.; Chien, M. J.; Ho, C.-T. Comparison of the volatile
compounds obtained from thermal degradation of cysteine and
glutathione in water. J. Agric. Food Chem. 1988, 36, 992−996.
(7) Zhang, Y. G.; Ho, C.-T. Volatile compounds formed from
thermal interaction of 2,4-decadienal with cysteine and glutathione. J.
Agric. Food Chem. 1989, 37, 1016−1020.
(8) Zhang, Y. G.; Ho, C.-T. Comparison of the volatile compounds
formed from the thermal reaction of glucose with cysteine and
glutathione. J. Agric. Food Chem. 1991, 39, 760−763.
(9) Zhang, Y. G.; Ho, C. T. Formation of meatlike aroma compounds
from thermal reaction of inosine 5′-monophosphate with cysteine and
glutathione. J. Agric. Food Chem. 1991, 39, 1145−1148.
(10) Oh, Y.-C.; Shu, C.-K.; Ho, C.-T. Some volatile compounds
formed from thermal interaction of glucose with glycine, diglycine,
triglycine, and tetraglycine. J. Agric. Food Chem. 1991, 39, 1553−1554.
(11) Lu, C. Y.; Hao, Z. G.; Payne, R.; Ho, C.-T. Effects of water
content on volatile generation and peptide degradation in the Maillard
reaction of glycine, diglycine, and triglycine. J. Agric. Food Chem. 2005,
53, 6443−6447.
(12) Van Lancker, F.; Adams, A.; De Kimpe, N. Formation of
pyrazines in Maillard model systems of lysine-containing dipeptides. J.
Agric. Food Chem. 2010, 58, 2470−2478.
(13) Rizzi, G. P. Role of phosphate and carboxylate ions in Maillard
browning. J. Agric. Food Chem. 2004, 52, 953−957.
(14) de Kok, P. M. T.; Rosing, E. A. E. Reactivity of peptides in the
Maillard reaction. ACS Symp. Ser. 1994, No. 543, 158−179.
(15) Hwang, H. I.; Hartman, T. G.; Rosen, R. T.; Lech, J.; Ho, C.-T.
Formation of pyrazines from the Maillard reaction of glucose and
lysine-α-amine-N-15. J. Agric. Food Chem. 1994, 42, 1000−1004.
(16) Negroni, M.; D’Agostina, A.; Arnoldi, A. Effects of olive, canola,
and sunflower oils on the formation of volatiles from the Maillard
reaction of lysine with xylose and glucose. J. Agric. Food Chem. 2001,
49, 439−445.
(17) Adams, A.; Polizzi, V.; van Boekel, M.; De Kimpe, N. Formation
of pyrazines and a novel pyrrole in Maillard model systems of 1,3-
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Van Lancker, Fien
