| Tea is a traditional drink in China, and is also one of the three major natural drinks in the world, consumed by two thirds of the world’s population. Tea trees have strong abilities to absorb minerals, because of which the tea not only contains major elements such as K, Ca, Mg but also trace elements like Zn, Sr, Fe, Cu. Mineral elements are indispensable component of the tea, and so the study of them are one of the most important aspect in tea studies. Over the decades, people have done a lot of research on tea garden soil, tea leaves and mineral elements to learn more about the tea tree nutrition, health functions of tea and tea safety. Variations of most of the mineral content in tea garden soil are not large, which show the tea growing area and mineral content are relatively stable. There is significant regular geographical difference in the levels of certain elements, and the existing form of the mineral elements in the soil affect the tea tree absorption significantly. Mineral substances in tea come in a wide variaty, the content of them differ greatly and also vary substantiallly, the variation impact factors are numerous. Mineral substance content in tea and its extraction rate are not only related to the geographical environment and climate conditions, but also the varieties of tea, the process of picking and manufacturing. Differences in the combination state of various mineral elements in tea make their extraction rate different.Under specific soil and climate conditions, the processing of different types of tea leaves in different ways make the content of minerals different in the tea. Thus correlations between minerals can be found through statistical analysis of the mineral substances, and based on the characteristic differences, we can identify tea producing areas and also its varieties. This study collected53soil samples from27sampling points in Guizhou Daozhenzhizhi county, with12steamed green tea samples and16Roasted samples. respectively, using Wet digestion and microwave digestion are applied to the sample processing, mineral elements in the samples are measured by ICP-OES, and data analysis was done using SPSS software. Through testing of14kinds of minerals in the soil samples, we found the soil in Daozhen tea garden contains Mn that was quite dispersed and differed greatly in its content. Substances such as Ca, Mg, Co, Cu, Sr, Zn, Mn were enriched in lower layers while those of Al, Mg, As, Cr, Ni were more enriched on the surface. There was no significant difference for Fe and V. The content Al, Mg, Co, Cu, Zn in Daozhen County tea garden soil were similar to values nationwide, but compared with Guizhou soil, it has higher Al content, and lower in Co, Cu, Zn. Elements such aas Fe, As, Ni, Cr, V, Mn were above the national average level. Fe, V and Mn content was lower than that of Guizhou, while Ni and V was lower than it. The average of Ca, Ba and Sr3were lower than that of Guizhou Province and also China soil in general. The detected Ca content is moderate in our studied tea garden, making it suitable for high-quality tea growing. As and Cr content met the tea plantations organic standards.There were significant correlations between the tea minerals, for instance, there were significant positive correlations between Al and Fe, Co, Cu, Ni, Zn, V. Guizhou Daozhenzizhi county have high concentrations of Ca, Mg, Mn, Al, Zn, Sr in steamed green tea, and moderate content in the rest of elements. Most of the roasted tea samples have moderate content of each element. The test results show the Michizane Gelao and Miao Autonomous County of Guizhou produced tea samples rich in minerals like Fe, Mn, Zn and Sr. The Tea elements extraction rate is associated with the number of brewing, tea and water ratio, water temperature, infuse time, time interval between two infuse and tea remains. By use of multivariate linear regression analysis, we obtained the importance rank of various factors, that is, tea and water ratio> tea and water ratio in the tea remains> number of brewing> temperature> brewing time> brewing time interval.The correlation analysis of the mineral elements reflects the synergy between them, which is important to guide tea garden fertilizing, increase fertilizing efficiency and improve qualities of the tea. Different tea varieties, growth conditions and different processing methods affect significantly the mineral contents. Principal component analysis showed that the minerals significantly different in their content can be used to distinguish production regions and tea varieties. |
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