Relationship Between Sensory Character And Chemical Components Of Congou’s Flavor

Black tea originated from Fujian province and was called "dark tea" at that time. It contains various kinds of chemical components which have many health care functions. With its unique flavor, Congou, which endemic to China is becoming increasingly popular among Chinese people and its physical and chemical qualities, aroma especially, are valued more than ever. This paper took 30 kinds of Congou as samples to study the components, especially volatile compounds, which form their typical characters and evaluated the characters with modern sensory evaluation system from which this paper acquired the following conclusions.1. Analysis on non-volatile compounds of CongouThe results of detection on the content of typical characters in 30 kinds of Congou showed that the content of TP in the majority was about 10% and 7% in the minority; The content of free amino acid, higher in H1, H21, H18, H15, varied from 1.05%-2.92%; Caffeine content was 26.63 mg/g on average. The ratio of TR/TF was about 10 and the content of TB was about 8%. The author adopt clustering analysis to divide 30 samples into 4 groups. Group 1 was consisted of samples with high content of TR, TP and intermediate content of caffeine; Group 2 included samples which had less TF, TB and intermediate content of TR; Group 3 included samples with high content of TP, TB and intermediate content of TF; Group 4 included samples with high content of TF and TR.2. Analysis on volatile compounds of CongouThere were 103 volatile compounds detected in 30 samples by GC-MS including 25 kinds of alcohol,25 aldehydes,15 easters,13 olefins,11 ketones,8 pyrazines,3 acids,2 hydrocarbons and 1 kind of sulfide. The aroma characters are very rich and each producer or producing area processes with different styles which make the characters differ from one to another. But there were 23 kinds of compounds all detected in 30 samples and marked the basic aroma of Congou. These compounds were linalool and its oxides, limonene, (E)-β-basil, methyl salicylate, phenylacetaldehyde, benzaldehyde, β-ionone, nerol, geraniol, phenethyl alcohol, geranial, nerolidol, ocimene, 2-methylbutyraldehyde, cis-3-hexen-l-ol. The author used PCA to find out the most contributory conponents in 30 samples which were nerol, (E)-β-basil, linalool and its oxides, myrcene, nerolidol, geraniol, geraniol, geranylacetone, trans-2-Nonenal, 1-Octen-3-ol, phenethyl alcohol,methyl salicylate,a-terpineol,β-Cyclocitral, isobutyraldehyde.3. Analysis on sensory character of CongouThis paper analyzed the sensory character of Congou by the method of qualitative description. It chose 19 sensory terms such as bitterness, astringency, sourness, umami, sweetness, aftertaste sweetness, strength, roasted flavor, camerlsed and so on to describe. The PCA results showed that it was feasible to evaluate the sensory character of 30 samples by this method because it could describe 75.74% of the sensory variation though samples resembled each other while possessing their own unique characters.Samples with plus-point on first principal component rated high on bitterness and astringency, relatively high on aftertaste and strength, low on fermented flavor but high on flowery flavor. Samples with plus-point on second principal component also rated high on bitterness, astringency and flowery flavor. Associating typical chemical components with sensory characters, Samples of group 1 in clustering analysis showed weak bitterness, astringency and relatively plain overall taste but strong sweetness, roasted flavor and heylike flavor; Samples in group 2 showed the strongest bitterness, astringency, aftertaste sweetness, lasting taste and relatively strong flowery flavor, fruity flavor and sweet aroma; Samples in group 3 showed quite ordinary character expect for strong herbal flavor and fermented flavor; Samples in group 4 showed relatively strong sourness and significantly strong camerlsed and roasted flavor among other three groups.