Volatiles from the Maillard Reaction of L-Ascorbic Acid and L-Alanine at Different pHs

The volatiles formed from the reactions of L-ascorbic acid with L-alanine at 5 different pH (5, 6, 7, 8, or 9) and $140{\pm}2^{\circ}C$ for 2 hr was performed using solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) analysis were identified to be 25 different kinds. The reaction between L-ascorbic acid and L-alanine led mainly to the formation of pyrazines. Many of these were alkylpyrazines, such as 3-ethyl-2,5-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine, 3,5-diethyl-2-methylpyrazine, methylpyrazine, 2-ethyl-6-methylpyrazine, and 2,3-diethyl-5-methylpyrazine, other compounds identified were furans, phenols, benzoquinones, 2,4,6-trimethylpyridine, and 2-methylbenzoxazole. The studies showed that furans, such as furfural and benzofuran were formed mainly at acidic pH. In contrast, higher pH values could promote the production of pyrazines.