Structure-dependent pyrolysis mechanisms of tobacco carbohydrates: from monosaccharides to polysaccharides under programmed and fast pyrolysis conditions

Abstract

This study systematically investigates the pyrolysis mechanisms of typical carbohydrates in tobacco under both fast pyrolysis (500 °C) and temperature-programmed conditions (50–500 °C), with a focus on their structural influences on product distributions and reaction pathways. Comparing the fast and temperature-programmed pyrolysis experiments reveals the pyrolysis pathways and product distributions of different structural sugars. Using Py-GC/MS analysis, we demonstrate that small-molecule sugars exhibit distinct pyrolysis behaviors: glucose favors diversified products through 1,2-enolization, while fructose preferentially forms furans via 2,3-enolization due to its ketose configuration. Macromolecular sugars display structure-dependent mechanisms: cellulose yields anhydrosugars through β-1,4-glycosidic cleavage; amylose's α-1,4-linked helical structure enhances anhydrosugar production (62.21%); and xylan's pentose units promote furfural selectivity (46.6%). The Maillard reaction with proline significantly alters pyrolysis pathways, introducing nitrogenous heterocycles and suppressing anhydrosugars while enhancing the ester formation. These findings elucidate the structure–activity relationships governing tobacco carbohydrate pyrolysis, offering a theoretical foundation for optimizing pyrolysis processes and developing functional flavor compounds.