Formation of styrene during the Maillard reaction is negligible

Abstract

The elucidation of chemical pathways and the identification of intermediates leading to vinylogous compounds such as acrylamide by the Maillard reaction have proven challenging. This study was conducted to assess the formation of styrene from L-phenylalanine, employing binary mixtures of the amino acid heated together with simple C(3)-sugar analogue (1-hydroxyacetone) or methylglyoxal. The formation of the corresponding vinylogous product, i.e. styrene, was measured under different moisture, pH, and temperature conditions. The formation of intermediates over time was monitored by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) together with the target compound styrene. Two intermediates, i.e. 1-phenethylaminopropan-2-one and 2-phenylethylamine, play a role in the formation of styrene, the latter of more importance in high-moisture systems, whilst the former favours the release of styrene in low-moisture systems. The model further showed that Strecker-type reactions are of less importance in the formation of styrene, as the yield from single immediate precursors was maximally 0.03 mol%. The low conversion rate of L-phenylalanine to the vinylogous product and existing data on the occurrence of free L-phenylalanine in food plants suggests that the amounts of styrene expected in foods subjected to thermal treatment are negligible.

Combined Urinary Biomarkers to Assess Coffee Intake Using Untargeted Metabolomics: Discovery in Three Pilot Human Intervention Studies and Validation in Cross-Sectional Studies

“…We also synthesized the 3,4-dihydroxy-styrene glucuronide, but it eluted earlier than M18. Nevertheless, the neutral loss of C 2 H 2 suggests that the deconjugated M18 is probably an isomer of dihydroxystyrene, most likely formed from the degradation of l -phenylalanine into styrene during the roasting procedure . Indeed, it has been shown that styrene can be aromatically hydroxylated by mouse liver microsomes .…”

“…Nevertheless, the neutral loss of C 2 H 2 suggests that the deconjugated M18 is probably an isomer of dihydroxystyrene, most likely formed from the degradation of L-phenylalanine into styrene during the roasting procedure. 38 Indeed, it has been shown that styrene can be aromatically hydroxylated by mouse liver microsomes. 39 The thermal degradation of Lphenylalanine to styrene, and its hydroxylation and further glucuronidation, can explain the presence of M18.…”

Carnitine, A New Precursor in the Formation of the Plant Growth Regulator Mepiquat

“…Researchers have demonstrated that the Maillard reaction under basically dry circumstances could result in release of the dangerous substances. Asparagine, glutamine, aspartic acid, and phenylalanine were developed for their potential to provide reactive intermediates, which have drawn special concern during the past few years. − Nikolov and Yaylayan showed that lysine could transform into pent-4-ene-1-amine through a decarboxylative and deamination reaction when heated at high temperature. Subsequent intramolecular cyclization of pent-4-ene-1-amine provided piperidine, which could react with methyl transfer reagent to form mepiquat. ,, In essence, mepiquat arises from a Maillard-type reaction that requires free lysine, a reducing sugar, and an alkylating agent, heated under typically dry conditions. , Recent studies show that pipecolic acid (PipAc) gives a major push to the constitution of mepiquat.…”

Role of choline and glycine betaine in the formation of N,N-dimethylpiperidinium (mepiquat) under Maillard reaction conditions

“…Research over the past years has shown that Maillard reaction-type mechanisms under essentially dry conditions can lead to the formation of vinylogous compounds amongst which acrylamide, derived from the amino acid asparagine, has raised particular attention in the past years (Stadler, Blank, Varga, et al 2002;Zyzak et al 2003;Goldmann et al 2009). …”

“…Other amino acids such as, for example, glutamine, aspartic acid and phenylalanine, have also been studied with regard to their potential to furnish reactive intermediates mostly under dry Maillard reaction conditions (Stadler et al 2003;Goldmann et al 2009). In a recent study, Nikolov and Yaylayan have shown that lysine, when subjected to high temperature, can be converted to pent-4-ene-1-amine in a decarboxylative deamination reaction analogous to that leading to acrylamide.…”