Researches On Growth Environment Of Laoshan Green Tea And Its Characteristics

In recent years, Qingdao Laoshan district has become a new green tea planting basein China. Although there are some theses or reports mentioning about research ofdifferent kinds of tea, barely has an academic thesis on Laoshan green tea been formallyreferred. Therefore it is deniable that the research of Laoshan green tea is of certainsignificance to the environment and economy of Laoshan district, as well as to the wholesociety.The main issues to be solved in this research are listed as follows:●geographical and geological environment of Laoshan green tea planting area●analysis and test techniqt, es on quality of Laoshan green tea●assessment on taoshan green teaDetermination of inorganic anions, aroma components and heavy rnetals in Laoshangreen tea are the main experimental work, which can objectively reflect the quality ofLaoshan green tea. In this research, several kinds of Laoshan green tea are analyzed.1 Detection of Radiation in Laoshan Green Tea Planting Area by Nuclear RadiationDetectorSand soil, formed in the process of granite weathering, is the main kind of soil forgrowth of Laoshan green tea. Radiation in granite area has caused the attention ofresearchers on environmental geochemistry, also it is important for the research ofenvironment and green food, which is just the field this project lies in.As is all well known, radiation is powerful enough to alter cellular chemicals anddisrupt normal cell functioning, which is harmful to human health. A Geiger-Muller tubewas used for this task. Several representative spots were selected in Laoshan green teagardens and radiation intensities ofγrays were monitored respectively.2 Determination of Inorganic Anions by Ion ChromatographyIon Chromatography(IC) is a very effective method for the analysis of inorganiccomponents in tea aqueous solution. In this research, the determination of 6 commoninorganic anions in seven varieties of Laoshan green teas and two others are presented. Itoffers objective experimental results for the quality research of Laoshan green tea. Sample pretreatment for impurity removal of complex matrix in tea solution is oneof the most important process before ion chromatograph (IC) analysis. For this purpose,high quality bentonite was used as adsorbent to take most of impurities away, and a ODScolumn was connected on the top of syringe for the elimination of organic impuritiesduring slow loading course. Fand other five inorganic anions in the extracting solutionof Laoshan green tea were determined quantitatively by conductivity detector mounted inion chromatograph PIC-8. The concentration of NO₂^- in each tea sample is below0.001mg/g, and for F^-, the representative anion, the concentrations are 0.994 to 2.087mg/g. Ranges of relative standard deviation (n=3) are 1.5%～2.7% and ranges ofaccuracy (shown as recovery) are 95.7%～104.0% for analytical results.3 Determination of Aroma by Gas Chromatograph-Mass Spectrometer (GC-MS)Aromatic materials were distilled and collected from Laoshan green tea in a methodof water-vapor distillation. The malerials in cool distilled liquid were extracted by ether.After dehydration by Na₂SO₄ and ether's controlling volatilization at 1 atm pressure and25℃room temperature, only 1.5mL organic liquid was left. The liquid was analyzed byGC-MS (GS3800, MS Saturn 2000, Varian, USA). 44 varieties of aroma components wereidentified and matched well with NIST spectrum library. It has been proved that Laoshangreen tea is rich in aroma.4 Determination of Heavy MetalsThe concentrations of such four metal ions as Zn2+, Cd²⁺, Pb²⁺ and Cu²⁺ inaqueous solution were determined by electrochemical stripping voltammetry withmercury-film electrode.