Abstract: The aroma compounds generated from a model reaction system of ascorbic acid (ASA) and cysteine (Cys) were identified by solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). The effects of pH and buffer concentration on the formation of aroma compounds were investigated. The major aroma compounds including furans, pyrazines, thiazoles, thiophenes, and alicyclic S compounds were generated in the model reaction system at various pH conditions. The types and amounts of these compounds could result in the formation of distinctive meat-like flavor. Furans were produced mainly under acidic pH conditions. In contrast, pyrazines were easy to generate in an alkaline environment. Thiazoles formation was not affected by pH, but high acidity could inhibit their generation. Neutral or slightly alkaline medium was conducive to the formation of thiophenes and alicyclic S compounds. Na2HPO4-NaH2PO4 buffer did not exhibit catalytic effect on the model reaction; on the other hand, its effect on aroma compound generation from model reaction system was exclusively concentrated on the ability to keep the pH stable. Therefore, 0.20 mol/L Na2HPO4-NaH2PO4 buffer is appropriate to maintain a relatively stable pH in the model reaction system.

Key words: Maillard reaction, ascorbic acid, aroma compound, solid-phase microextraction, pH, buffer