Analysis of Characteristics and Flavor Components of Alpinia officinarum Hance from Different Years

Alpinia officinarum Hance (galangal) was a perennial herb. In order to study the correlation between characteristics and flavor components of galangal in different years, samples from five different years (1 to 5 years, Y1~Y5) were collected to analyze the changes such as thickness, size, hardness and powder amount during growth. The flavor components were determined by gas chromatography mass spectrometry (GC-MS) and liquid chromatography time-of-flight mass spectrometry (LC-TOF MS) and analyzed statistically. The results showed that the volume of galangal in Y4 was significantly (P<0.05) larger than that in other years, and the hardness and powder amount increased with the growth cycle. The extraction rate of galangal oil (2.58±0.07 mL/100 g) and extraction amount (1.32±0.04 mL) of Y4 were significantly (P<0.05) higher than those of other years. A total of 46 volatile compounds including monoterpenes, oxygen-containing monoterpenes, sesquiterpenes, oxygen-containing sesquiterpenes and ketone esters were identified by GC-MS. The content of eucalyptol (15.52%~22.85%) was the highest. Oxygen-containing monoterpenes were mainly compounds in volatile oil of Y1~Y4 galangal, and sesquiterpenes were mainly compounds in volatile oil of Y5 galangal. There were significant differences in the relative content of volatile oil components in different years. Galangal in Y4, Y5 and Y1~Y3 could be clustered into two groups by principal component and cluster heat map analysis. The highest contribution to PC1 included phenethyl isobutyrate, camphene hydrate, camphene and β-selinene. The higher contribution to PC2 included cubenol, germacrene B, epoxycaryophyllene and nerolidol. The data detected by LC-TOF-MS were showed that the content of the bitter component galangin in Y3 and Y4 (10.58±0.25 mg/g, 10.45±0.12 mg/g) was significantly (P<0.05) higher than that in other years, and the content of spicy component diphenylheptane A (DHPA) in Y2 (3.74±0.10 mg/g) was significantly (P<0.05) higher than that in other years. According to the correlation analysis, there was a positive correlation between the characters and the flavor components in different years. The characters were closely correlated with the year (P<0.05), and the characteristic aroma was significantly correlated with the characters (P<0.01). The flavor galangin and DHPA were only significantly correlated with each other (P<0.05). The above results are helpful to guide the accurate harvest and high quality application of galangal.