Raspberry Ketone as a Contributor to the Sweet, Fruity Flavor of Heated Tobacco ( Nicotiana tabacum L.) Leaves and Insights into Its Occurrence Form

Raspberry ketone was identified as a contributor to the sweet, fruity flavor of heated Taoerxing Pushan Yezi (TPY) tobacco (Nicotiana tabacum L.) leaves through comparisons with an authentic standard, exploratory gas chromatography-olfactometry (GC-O), and descriptive sensory evaluation of spiked samples. Adding 2.0 mg/kg to a Japanese cultivar lacking berry-like aroma elicited qualitative comments on body (flavor richness and fullness), mellowness, softness, and reduced irritation. TDU-GC-MS/MS, which heats leaf samples in the inlet unit, detected 2–9 ppm in TPY leaves. Most importantly, amylase and protease treatments increased free raspberry ketone. LC-MS/MS, without sample heating during measurement, quantified 0.6 mg/kg in the control, versus 2.8, 5.4, and 9.0 mg/kg after amylase, protease, and β-glucosidase treatments, respectively. These results suggest that free raspberry ketone may be retained within a matrix containing starch, proteins, and polyphenolic glycosides, or that raspberry ketone occurs as glycosides, and that it is released upon heating during smoking.