Mechanisms of Alkylpyrazine Formation in a Potato Model System Containing Added Glycine

Abstract

The use of glycine to limit acrylamide formation during the heating of a potato model system was also found to alter the relative proportions of alkylpyrazines. The addition of glycine increased the quantities of several alkylpyrazines, and labeling studies using [2-13C]glycine showed that those alkylpyrazines which increased in the presence of glycine had at least one 13C-labeled methyl substituent derived from glycine. The distribution of 13C within the pyrazines suggested two pathways by which glycine, and other amino acids, participate in alkylpyrazine formation, and showed the relative contribution of each pathway. Alkylpyrazines that involve glycine in both formation pathways displayed the largest relative increases with glycine addition. The study provided an insight into the sensitivity of alkylpyrazine formation to the amino acid composition in a heated food and demonstrated the importance of those amino acids that are able to contribute an alkyl substituent. This may aid in estimating the impact of amino acid addition on pyrazine formation, when amino acids are added to foods for acrylamide mitigation.

Characteristic chemical components of the essential oil from white kwao krua (Pueraria mirifica)

“…In addition, aldehydes and alcohols of the same carbon chain and pyrazine-type, such as methylpyrazine, 3-ethyl-2,5-dimethylpyrazine, and tetramethylpyrazine, were detected in P. mirifica oil. Pyrazine compounds are considered to be products of the Maillard reaction 15 .…”

Thermal generation or aroma

“…However, these mechanisms have not been identified in food matrices. In two model food systems (Low et al, 2007;Parker et al, 2010), mass spectra of the fragments confirmed that the ring carbons were derived exclusively from glucose. Furthermore, serine has also been shown to be a precursor of pyrazines .…”

“…This is the non-oxidative route that could equally provide one of the methyl groups via formaldehyde condensation. Evidence of these different mechanisms has been found in potato cakes where addition of [2-13 C] glycine confirmed that some of the methyl-substituents were derived from glycine (Low et al, 2007). Likewise, use of [ 13 C 6 ] glucose in a meat-based pet food system showed that some of the substituents were not glucose-derived .…”

“…This poses a challenge for the food industry because many strategies to reduce acrylamide, also reduce flavour formation. Such are the complexities of the Maillard reaction that several authors have turned to mathematical kinetic modelling based on the underlying chemistry to determine the control points in the reaction (Low et al, 2007;Parker et al, 2012) and develop strategies to minimise acrylamide whilst maintaining flavour.…”

Effects of sulphur nutrition during potato cultivation on the formation of acrylamide and aroma compounds during cooking

“…Two amino acids important in aroma formation, alanine and glycine, increased in relative, as well as absolute terms, in Maris Piper and King Edward, whereas they showed no relative increase in Prairie. In fact, alanine decreased slightly in Prairie in relative terms and may be the reason why some pyrazines are actually lower in SÀ Prairie than in S+ Prairie, e.g., ethylpyrazine, 2-ethyl-5-methylpyrazine and 2-ethyl-6-methylpyrazine (compounds where acetaldehyde from alanine breakdown may provide the ethyl side-chain (Low, Parker, & Mottram, 2007)). Threonine also showed no relative increase in SÀ Prairie potatoes and the relative increase in serine was small compared with that observed in Maris Piper and King Edward.…”