Preparation method of high-nicotine tobacco extract

The invention discloses a preparation method of a high-nicotine tobacco extract. The preparation method of the high-nicotine tobacco extract belongs to the field of tobacco additives, and mainly comprises three steps of raw material pretreatment, subcritical extraction and molecular distillation. A baking process is adopted for pretreating tobacco leaves, so that reducing sugar of tobacco and a nitrogen-containing compound are promoted to generate maillard reaction, substances such as pyrone and furanone are produced, the baking aroma is improved, the reducing sugar content is reduced, the suction offensive odor is reduced, meanwhile, combined-state nicotine in the tobacco leaves is converted into a free state, and the content of the free-state nicotine is improved. A weak polar solvent is adopted for subcritical extraction, so that the extraction rate of tobacco feature aroma substances and the free-state nicotine can be improved; and low-temperature molecular distillation is combined, so that low-boiling-point aroma substances and the nicotine can be effectively enriched, the damage on thermosensitive substances due to high temperature is avoided, and meanwhile, the content of macromolecular substances such as pectin and protein in an extract is reduced. The method is simple in preparation process, simple and convenient to operate, and suitable for industrial production and application.