In order to promote the quality of brick tea and reduce its fluoride content, the fluoride contents in leaves of 25 tea varieties at the .stage of one bud and five leaves were determined by the method of fluodde-ion s...In order to promote the quality of brick tea and reduce its fluoride content, the fluoride contents in leaves of 25 tea varieties at the .stage of one bud and five leaves were determined by the method of fluodde-ion selective electrode method. The results showed that the fluodde contents in the 25 varieties were in the range of 181.92-345.06 mg/kg, end the fluoride content in ＇Zhongcha 302＇ was the lowest. Based on traditional production process of brick tea, 3 new low-fluoride brick tea production processes with ＇Zhongcha 302＇ as the raw material at the stage of one bud and five leaves were constructed. The fluoride content, physicochemical in- dex, sensory end main chemical contents in the brick tea samples were determined. The best processing process of Iow-fluodde brick tea was process 3, which included aldng, fixing, rolling, second fixing, second roiling, sun-drying, pile-fermentation, steaming, pile-fermentation, drying and shaping into brick by vapor treating. The re- sults showed that the fluoride content and physicochemical index of the brick tea sample of the third low-fluoride brick tea production process accorded with National Standard GB/T 9833.4-2013. The sensory evaluation of the brick tea sample was better than that of brick tea manufacture by the traditional process. The water extract, tea polyphenols, amino acids, caffeine and water-soluble sugar in the brick tea sample increased by 9.41%, 36.39%, 26.94%, 27.23% and 15.29%, respectively. Low-fluodds bdck tea could be produced by selecting low fluoride tea varieties, controlling the tondemess of fresh leaves, and optimizing the processing technique.展开更多
The distribution of Al and F contents and the relationship between Al and F in tea plants and soils of 12 tea gardens in Central and Southwest China were investigated from October 31 to November 14, 2006. The results ...The distribution of Al and F contents and the relationship between Al and F in tea plants and soils of 12 tea gardens in Central and Southwest China were investigated from October 31 to November 14, 2006. The results show that there were differences in pH, CEC, the contents of organic matter （OM）, Al and F in the different soils of the tea gardens. The Al content ranged from 1196 to 7976mg/kg for old leaf, 370 to 2681mg/kg for young leaf and 285 to 525mg/kg for stem, whereas the content of F ranged from 221 to 1504mg/kg for old leaf, 49 to 602mg/kg for young leaf and 13.5 to 77.5mg/kg for stem. The concentrations of labile Al varied obviously in the different soils, but the distribution law of labile Al content for the same garden was Alexchangeable≈AlFe.Mn oxide〉Alorganic〉mlwater.soluble. The contents of different labile F fractions varied slightly in the different soils and the different soil layers, though the exchangeable F content was lowest among the labile F in the soils. The concentrations of Al and F in tea plants increased with increasing amount of water-soluble Al or F, especially the amount of water-soluble fractions in the soil layer of 0-20cm. The correlation between Al content and F content in the tea leaf was more significant than that in the tea stem. Furthermore, the correlation between Al content and F content in whole tea plant was strongly significant （r=0.8763, p〈0.01, n=36）. There were evident tendency that Al concentration increased with the increase of F concentration in different soil layers. The correlation of water-soluble Al with water-soluble F in all soils was also strongly significant （r=0.7029, p〈0.01, n=34）. The results may provide a proof that Al and F are jointly taken up by tea plants to some extent in natural tea gardens.展开更多
文摘In order to promote the quality of brick tea and reduce its fluoride content, the fluoride contents in leaves of 25 tea varieties at the .stage of one bud and five leaves were determined by the method of fluodde-ion selective electrode method. The results showed that the fluodde contents in the 25 varieties were in the range of 181.92-345.06 mg/kg, end the fluoride content in ＇Zhongcha 302＇ was the lowest. Based on traditional production process of brick tea, 3 new low-fluoride brick tea production processes with ＇Zhongcha 302＇ as the raw material at the stage of one bud and five leaves were constructed. The fluoride content, physicochemical in- dex, sensory end main chemical contents in the brick tea samples were determined. The best processing process of Iow-fluodde brick tea was process 3, which included aldng, fixing, rolling, second fixing, second roiling, sun-drying, pile-fermentation, steaming, pile-fermentation, drying and shaping into brick by vapor treating. The re- sults showed that the fluoride content and physicochemical index of the brick tea sample of the third low-fluoride brick tea production process accorded with National Standard GB/T 9833.4-2013. The sensory evaluation of the brick tea sample was better than that of brick tea manufacture by the traditional process. The water extract, tea polyphenols, amino acids, caffeine and water-soluble sugar in the brick tea sample increased by 9.41%, 36.39%, 26.94%, 27.23% and 15.29%, respectively. Low-fluodds bdck tea could be produced by selecting low fluoride tea varieties, controlling the tondemess of fresh leaves, and optimizing the processing technique.
基金Under the auspices of National Natural Science Foundation of China (No. 40573052)
文摘The distribution of Al and F contents and the relationship between Al and F in tea plants and soils of 12 tea gardens in Central and Southwest China were investigated from October 31 to November 14, 2006. The results show that there were differences in pH, CEC, the contents of organic matter （OM）, Al and F in the different soils of the tea gardens. The Al content ranged from 1196 to 7976mg/kg for old leaf, 370 to 2681mg/kg for young leaf and 285 to 525mg/kg for stem, whereas the content of F ranged from 221 to 1504mg/kg for old leaf, 49 to 602mg/kg for young leaf and 13.5 to 77.5mg/kg for stem. The concentrations of labile Al varied obviously in the different soils, but the distribution law of labile Al content for the same garden was Alexchangeable≈AlFe.Mn oxide〉Alorganic〉mlwater.soluble. The contents of different labile F fractions varied slightly in the different soils and the different soil layers, though the exchangeable F content was lowest among the labile F in the soils. The concentrations of Al and F in tea plants increased with increasing amount of water-soluble Al or F, especially the amount of water-soluble fractions in the soil layer of 0-20cm. The correlation between Al content and F content in the tea leaf was more significant than that in the tea stem. Furthermore, the correlation between Al content and F content in whole tea plant was strongly significant （r=0.8763, p〈0.01, n=36）. There were evident tendency that Al concentration increased with the increase of F concentration in different soil layers. The correlation of water-soluble Al with water-soluble F in all soils was also strongly significant （r=0.7029, p〈0.01, n=34）. The results may provide a proof that Al and F are jointly taken up by tea plants to some extent in natural tea gardens.
