The Roles of Amino Acids and Sugars in the Production of Volatile Materials in Microwave Heated Tobacco Dust Suspensions

Abstract

Abstract For the first time, the role(s) of selected amino acids and sugars in the production of volatile compounds in microwave prepared heat treated tobacco suspensions (HTTS) has been unambiguously defined. The role can be expressed in two major reaction pathways: 1) Strecker degradation of amino acids and 2) amino acid/sugar Maillard-type reactions. The mechanism of the Strecker degradation was confirmed by the addition of selected 13C- labelled amino acids to the reaction suspension. The addition of the amino acid resulted in a dramatic increase in the concentration of the specific, appropriate, low molecular weight Strecker aldehyde in the headspace above the reaction suspension. The mechanism of the amino acid/sugar Maillard-type reactions was substantiated by: 1) adding a wide array of amino acids to the suspension; 2) by employing 15N-labelled amino acids; and 3) employing 13C-labelled sugars. Addition of amino acids to the suspension followed by heat treatment resulted in significant increases (2 ×) in the concentration of volatile pyrazines relative to the control. Most amino acids significantly increased the concentration of headspace pyrazines. Reactivity differences, as a function of sugars, was also demonstrated. Analysis of the headspace above suspensions incorporating 15N-labelled amino acids and 13C-labelled sugars revealed the 15N and 13C atoms to have been distributed throughout a wide array of volatile pyrazines. The distribution of the 15N atoms within the pyrazines was unique to the amino acid and the distribution of the 13C atoms was linked to the type of sugar employed. These results have documented for the first time in a heat treated tobacco formulation the mechanisms of amino acids and sugars in the production of volatile compounds which have documented intense sensory characteristics.