| In this paper,white teas were used as test materials,and investigated on the dissolution of their contents in brews infused in 3 series respectively,the correlation between the dissolved contents and the qualities of the related brews based on determination of chemical composition and sensory evaluation.The results were as follows:(1)The contents of water extract,polyphenol and soluble sugar in the tested white tea were higher,accounting for 46.18%～47.70%、16.59%～17.46%、7.89%～8.07%on a basis of dry weight respectively.Among catechin and aminoacid components,EGCG、ECG、The、Asn、Gln and Ser were higher in content,accounting for 65.33%～67.54%、17.09%～21.08%of total catechins,and 40.15%～47.09%、6.55%～11.73%、5.75%～9.98%、3.90%～4.81%of total amino acids,respectively.The above components were contributions to the white tea quality and flavor.(2)The total dissolution rate ordered from high to low in three times of brewing ranked as caffeine、flavone、theabrownin、thearubigin、water extract、polyphenol、soluble sugar、amino acid and theaflavin,accounting for 78.94%、69.47%、63.98%、61.96%、57.62%、55.77%、53.26%、50.42%、31.34%of the mean total dissolution rate,respectively(3)When compared between 3 series of brews,the other components decreased in order of dissolution rate from the 1 st to the 3rd brew except for thearubigin。The followings were listed as dissolution rates of components tested in 1st brew、in 2nd brew、in 3rd brew respectively:water extract 25.93%～28.50%、17.59%～19.15%、11.19%～13.43%;polyphenol 21.36%～26.18%、17.47%～19.35%、11.74%～14.53%;soluble sugar 7.60%～18.00%、17.60%～18.00%、17.60%～17.87%;aminoacid16.82%～19.72%、16.24%～17.66%、14.86%～16.06%;caffeine 32.18%～40.69%、26.06%～30.40%、12.50%～14.95%;flavone 20.75%～38.12%、16.87%～26.67%、13.85%～20.51%;thearubigin 13.59%～14.08%、16.02%～16.95%、30.60%～32.40%;theaflavin 10.55%～17.18%、10.03%～10.71%、8.04%～9.41%;theabrownin 22.39%～23.04%、23.08%～23.53%、17.60%～17.87%。One of the components was different in its dissolution rates between 1st brew、2nd brew、3rd brew,and may be classed as significant difference、big difference or little difference,of the significant difference was theabrownin with an average dissolution rate difference of 20.32%between 1st and 2nd brew,and 90.90%between 2nd and 3rd brew;of the big difference were caffeine、flavone、water extract、theaflavin and polyphenol with an average dissolution rate difference of 10%～55%;of the little difference were soluble sugar and amino acid with an average dissolution rate difference of less than 10%(4)The contents GC,C and CG were not detected in 3 series of brews,while EGCG was on an average dissolution rate of 16.84%in 1st brew、15.13%in 2nd brew、11.33%in 3rd brew with a total rate of 43.31%;ECG so ranked was14.83%、14.45%、11.28%with a total rate of40.56%When compared between 3 series of brews,Glu、Asp、Tyr、Ser were higher on total dissolution rates of 67.57%～99.64%、68.22%～84.69%、69.62%～85.07%and 72.33%～78.42%respectively,and Glu was quite different in its dissolution rates between the 3 brewings with an average dissolution rate difference of 65.85%between 1st and 2nd brew、68.87%between 2nd and 3rd brew;The、Gln and Phe showed less difference in dissolution rates between 1st and 2nd brew with an average dissolution rates of 4.33%、11.37%、16.09%respectively,but more difference between 2nd and 3rd brew with an average dissolution rates of37.95%、41.73%、36.99%respectively.His and Pro so compared were quite different in some instances depending on series of brewing.It was revealed that differences of components in their dissolved amounts with different dissolution rates in 1st～3rd brews indicated their different contributions to the brews infused initially or longer(5)Dissolution rates of components showed a quite range of difference as far as the cultivars and tea grades were concerned,especially concerning some catechins or amino acids(6)Sensory evaluation showed that all the brews so infused with the 4 tea varieties,scored in the decreasing order of 1st brew>2nd brew>3rd brew except for 3 brewsWhen compared between the same grade、infusing water and infusing times,teas processed from Fuding big white were generally better than those processed from Fuding big white in respect of the thick、brisk、refreshing and mellow taste(7)Statistical analysis revealed that the main chemical components related to white tea thick、brisk taste were flavonoid(0.848**)、caffeine(0.795**)、amino acid(0.736**)、water extract(0.677*)、polyphenol(0.622*)、thearubigin(-0.588*)and The(0.919**)、GCG(0.855**),and that the main chemical components related to white tea refreshing、mellow taste were flavonoid(0.899**)、caffeine(0.843**)、amino acid(0.805**)、water extract(0.711**)、polyphenol(0.673*)、thearubigin(-0.633*)、and Asn(0.923**)、The(0.923**)、GCG(0.846**)and EGCG(0.628*) when quantitative analysis was applied,the evaluation models for"thick、brisk"and "refreshing、mellow" factors were established as follows F 1=0.97X1+0.87X2-0.511X3+0.906X4+0.956X5+0.867X6 F 2=0.058X1-0.324X2+0.825X3+0.386X4-0.114X5+0.469X6、F=74.07F 1+19.524F2(X1-6 refers to the contents of caffeine、flavonoid、thearubigin、water extract、amino acid、polyphenol;F refers to the comprehensive evaluation index of "thick、brisk" and"refreshing、mellow"factors).Further more the evaluation model for "thick、brisk" factors was as follows:F=0.970X1+0.967X2+0.964X3(F refers to the main components for "thick、brisk" taste;X1-3 refers to the contents of caffeine、flavonoid、amino acid),and the cumulative variance contribution rate of of the first principal factor reached 93.55%.F=195.506X+59.516(F refers to "thick、brisk";X refers to GCG),R2=0.704.F=30.861+10.262X(F refers to "thick、brisk";X refers to The),R side=0.845.The evaluation model for "refreshing、mellow" factors was as follows:F=0.982X1+0.950X2+0.926X3+0.946X4(F refers to the main components for "refreshing、mellow" taste;X1-4 refers to the contents of caffeine、flavonoid、water extract、amino acid).The cumulative variance contribution rate of the first principal factor reached 90.507%F=20.199X1+174.641X2+29.815(F refers to "refreshing、mellow ";X1 refers to EGCG;X2 refers to GCG),R2=0.788 F=29.044+5.917X1+10.179X2(X1 refers to The;X2 refers to Asn),R2=0.907. |
PDF Full Text Request