Comparative analysis of asparagus tea processing and flavor component analysis

Blanching plays important roles in shaping the volatile profile of asparagus tea. In this study, the flavor of blanched and unblanched asparagus teas were studied in detail by electronic nose (E-nose), electronic tongue (Etongue) and gas chromatography-mass spectrometry (GC-MS) coupled with chemometrics methods. Sensory evaluation showed that in blanched asparagus tea, sweet aroma was significant improved, whereas grassy and harsh smell were declined. Linear discriminant analysis (LDA) of the E-nose data showed a clear discrimination between the blanched and unblanched samples. Volatile metabolites analysis showed that blanching treatment generally resulted in a decrease in aldehydes, pyrroles, pyrazines and an increase in ketones and hydrocarbons. Furthermore, styrene, nerylacetone, pentanal, and heptanal were identified as key compounds causing sweet aroma in blanched asparagus teas. While benzothiazole, 2-pentylfuran, naphthalene and several additional compounds are responsible for the green odor in unblanched asparagus teas. The E-tongue and antioxidant activity showed that blanched improved the quality of asparagus tea. These results provided a new insight and scientific basis to improve the processing techniques and quality control for asparagus tea.