THE EFFECT OF PH ON THE FORMATION OF VOLATILE COMPOUNDS PRODUCED BY HEATING A MODEL SYSTEM CONTAINING 5'-IMP AND CYSTEINE

The identification of volatile compounds formed from the reactions of Inosine-5'-Monophosphate (5'-IMP) with Cysteine at three different pH (3.0; 4.5; 6.0) and 140 degrees C were performed using dynamic headspa ce analysis. The results gave over 90 volatile compounds, mainly heter ocyclic compounds, including sulphur containing furans, thiophenes, th iazoles, furans, alkyl sulphides, bicyclic compounds and cyclic sulphi des. The studies showed that sulphur-substituted furans, mercaptoketon es and alkylfurans were formed mainly at acidic pH, while pyrazines we re completely inhibited at high pH. These findings support an earlier observation that pH has a great influence on volatile compounds formed in Maillard type reactions.