Preparation of an exogenous additive from Psoralea corylifolia fruit and its flavor-modifying effects on cigar tobacco leaves.

Psoralea corylifolia fruit (PCF) is a well-known traditional Chinese medicine and food, but its potential applications as a flavor-modifying exogenous additive (EA) for cigar fermentation has rarely been reported. In this study, a new type of PCF-derived EA was developed by enzymatic hydrolysis using a combination of single-factor and response surface experiments. The flavor compounds were analyzed by gas chromatography‒mass spectrometry (GC‒MS), and the flavor-modifying effects on cigar tobacco leaves were validated. Single-factor experiments indicated that the optimized conditions were an enzyme addition amount of 1.0% (w/w), a reaction temperature of 35 °C, and a reaction time of 24 h. The response surface model revealed that three investigated factors influenced the sensory evaluation scores in the following order: reaction time > reaction temperature > enzyme addition amount. GC‒MS analysis revealed a remarkable 9.6-fold increase in total volatile compounds of PCF-derived EA (21464.01 µg/mL) compared with P. corylifolia fruit homogenate (FH, 2239.60 µg/mL). The key flavor compounds with significantly increased contents included (S)-bakuchiol, isopsoralen, ficusin, β-caryophyllene, and β-caryophyllene oxide, which collectively contribute to bean, milky, floral, and sweetness aromas. After fermentation with EA, Chuxue 14 cigar tobacco leaves (CTLs) exhibited significant increases in bean and honey sweet aromas, which could be positively associated with the increased contents of flavor compounds such as (S)-bakuchiol, 3,4-dihydro-4,4-dimethyl-coumarin-6-ol, benzoic acid, and phenylacetic acid. This is the first report that PCF can be developed as a flavor-modifying EA for CTL fermentation.