[关键词]
[摘要]
为研究黔产市售绿茶中重金属的浸出规律,以五个生产加工地的黔产市售绿茶为研究对象,分析其9种重金属(Pb、Cr、Cd、Hg、Cu、Zn、Mn、Ni和As)含量,考察浸泡温度、浸泡时间、浸泡次数对茶叶重金属浸出率的影响。结果如下:茶叶中Cr、Mn、Ni、Cu、Zn、As、Cd、Hg和Pb含量分别为3.98~4.63、320.04~526.74、17.43~25.74、15.00~23.15、27.68~42.23、1.12~1.34、0.72~1.06、0.11~0.13和1.20~1.45 mg/kg,其中Cr、Cd、Pb、Hg和As含量均低于国家限量标准。绿茶中重金属的浸出率与浸泡时间和浸泡温度均呈正相关(p<0.05),而与浸泡次数呈负相关(p>0.05),黔产市售绿茶经三次浸泡后,浸出率Zn、Mn最高,分别为78.73%~87.04%、74.87%~81.27%;Hg次之,为32.25%~45.84%;Ni最低,为7.78%~11.58%。重金属的浸出率表现为Zn>Mn>Hg>As>Cd>Pb>Cr> Cu>Ni。浸泡温度为80 ℃、浸泡时间为40 min时,绿茶中重金属的浸出率最大;超过80 ℃、40 min后,重金属的浸出率增长趋于平缓。
[Key word]
[Abstract]
In order to investigate the distribution characteristics of heavy metals in tea, the green tea samples of five production and processing areas commercially available from urban markets in Guizhou Province were collected for monitoring the contents of heavy metals such as Pb, Cr, Cd, Hg, Cu, Zn, Mn, Ni and As. The effects of brewing temperature, brewing time and brewing times on heavy metal leaching rate of tea were investigated. The results were as follows: the content of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb were 3.98~4.63, 320.04~526.74, 17.43~25.74, 15.00~23.15, 27.68~42.23, 1.12~1.34, 0.72~1.06, 0.11~0.13 and 1.20~1.45 mg/kg, respectively. The contents of Cr, Cd, Pb, Hg and As in green teas of five areas were all lower than national standard. The diffusion rate of heavy metals in green tea was positively correlated with the brewing time and brewing temperature (p<0.05), and negatively correlated with the brewing times (p>0.05). Zn and Mn were shown to have the highest diffusion rate in tea infusion after three times of brewing, which were 78.73%~87.04% and 74.87%~81.27%, respectively; followed by Hg (32.25%~45.84%); and Ni was the lowest (7.78%~11.58%). The diffusion rate in tea infusion was ordered as: Zn>Mn>Hg>As>Cd>Pb>Cr>Cu>Ni. When the brewing temperature was 80 ℃ and the brewing time was 40 min, the diffusion rate of heavy metals in green tea was the largest. After 80 ℃ and 40 min, the diffusion rate of heavy metals increased gradually.
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[基金项目]
贵阳市高层次创新型青年卫生人才培养计划项目([2018]筑卫计科技合同字第023号);贵州省疾病预防控制中心科学(青年)技术基金项目(2017-E1-2青)