Changes in Levels of Amino Acids and Basic Components in Burley Tobacco Produced by Roasting

Three burley tobacco samples from three different areas in China and Brazil were roasted under three processing conditions. The amino acids and basic components of the burley tobacco samples were determined before and after roasting. Routine tobacco variables (reducing sugars, total water-soluble sugars, total nitrogen, total alkaloids, total volatile bases, and pH) were determined according to the Chinese National Standard Methods (CNSM). Free amino acids were determined by high performance liquid chromatography (HPLC). The basic compounds were isolated by use of simultaneous distillation and extraction (SDE) equipment. Their levels were determined qualitatively and quantitatively on a) a gas chromatograph (GC) equipped with a nitrogen-phosphorus detector (NPD) and b) by gas chromatography mass spectrometry (GC-MS). The results indicated that the chemical changes occurring during roasting have a significant impact on burley tobacco quality. Roasting decreased the tobacco pH value and the levels of total nitrogen, reducing sugars, free amino acids, and other nitrogenous substances, such as amines and alkaloids. The latter are usually related to the irritancy and sharp taste of burley tobacco smoke. In contrast, the levels of pyrazines, important contributors to the characteristic burley flavor, increased.