Tea Aroma Analysis Based on Solvent-Assisted Flavor Evaporation Enrichment

Presented here is a method for enriching and analyzing the volatile components of tea extracts using solvent-assisted flavor evaporation and solvent extraction followed by gas chromatography-mass spectrometry, which can be applied to all types of tea samples.

We explore the molecular basis of taste and aroma focusing on tea products derived from the Camellia sinensis plant. Our aim is to characterize the flavor molecules and investigate the biochemical processes affecting the sensory attributes of tea. Analyzing tea aroma requires the separation and enrichment of volatiles present in very low concentrations from the complex matrix of tea samples.

The sample preparation method often poses the most significant challenge and is critical for obtaining valid data leading to meaningful research conclusions. Through our systematic study on aroma formation, we successfully identified the methyl epijasmonate as the key compound responsible for the tea's aroma. We also categorized the aromas of four different white tea varieties.

The SAFE technique, unlike the commonly used methods for tea aroma preparation, provides a clear from a tea infusion free of non-violite compounds. Aroma compounds can be easily enriched through solvent extraction. Most importantly, the order profile of the orbitant aroma concentrate closely resembles that of the origin sample.

The proposed method can contribute to various research objectives, such as understanding the evolution of aroma from the tea plan to the tea cup, investigating the chemistry of specific molecules that impact sensory ecology, characterizing tea aroma to guide plant cultivation, process improvement, quality control, and the creation of new flavors. Begin by installing the solvent assisted flavor evaporation or SAFE glass assembly. Then connect the distillation bottle at the lower left connection site, and the collection bottle at the lower right connection site of the assembly.

Connect the circulating water tube to the rear portion of the assembly, ensuring the inlet enters the top and the outlet exits from the bottom. After installing the cold trap, connect the upper right opening of the trap to the vacuum pump with a tube. Set the temperature of the circulating water to 50 degrees Celsius and that of the water bath for the sample distillation flask to 40 degrees Celsius.

Then close the vacuum valve, switch on the vacuum pump to initiate the vacuum application. To prepare for sample distillation, first start the water circulation. Add liquid nitrogen into the cold trap, as well as surround the collecting bottle with liquid nitrogen.

Pour the tea infusion into the sample funnel at the top left and then cover it with a glass stopper. Next, gradually introduce the sample into the distillation flask drop-wise. Control the sample drop speed to maintain the vacuum within the proper range.

After the distillation completes, press the control button of the vacuum pump, and when stop flashes, press the enter key to confirm. When the speed of the vacuum pump decreases to zero, unplug the power cord. Remove the grinding plug above the sampling bottle, then unscrew the knob of the vacuum valve slowly to restore the system to atmospheric pressure.

Once atmospheric pressure is restored in the system, remove the liquid nitrogen surrounding the collection bottle. Slowly unscrew the collection bottle and carefully remove the bottle containing the sample. Finally, stop the water circulation.