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目的掌握不同生产年份普洱茶稀土残留状况,了解普洱茶稀土残留变化趋势。方法 2013—2015年在超市、批发市场、零售店、餐饮单位、茶博会、网购6类环节采集生产年份明确的264份普洱茶样品,使用Agilent 7700 Series电感耦合等离子体质谱仪,依据GB 5009.94—2012《食品安全国家标准植物性食品中稀土元素的测定》方法测定总稀土氧化物含量。结果 2010年以前生产的普洱茶稀土超标率均显著高于2010—2015年生产的普洱茶(χ~2=13.504,P<0.05);2010年以前生产的普洱茶中位数、平均值、P_(90)高于2010—2015年生产的普洱茶;2010年以前生产的普洱茶稀土残留量高于2010—2015年生产的普洱茶(Mann-Whitney U=5 758.000,Wilcoxon W=18 638.000,Z=4.226,P<0.05)。从分布范围看,普洱茶稀土残留量主要分布在1.0~3.0 mg/kg之间,2010年以前生产的普洱茶稀土残留分布区间较2010—2015年生产的普洱茶数值高。结论不同年份普洱茶稀土残留状况存在差异,2010-2015年份生产的普洱茶稀土残留问题较2010年之前有所好转。
Objective To understand the status of rare earth residues in Pu’er tea in different production years and understand the trend of rare earth residues in Pu’er tea. Methods A total of 264 Pu-Erh samples with clear production year were collected from 6 categories including supermarkets, wholesale markets, retail stores, catering units, tea expo and online shopping from 2013 to 2015 using an Agilent 7700 Series Inductively Coupled Plasma Mass Spectrometer. According to GB 5009.94 -2012 “National Food Safety Standard Determination of rare earth elements in plant foods” method for the determination of total rare earth oxide content. Results The over-standard rate of Pu-erh tea produced before 2010 was significantly higher than that of Pu-erh tea produced in 2010-2015 (χ ~ 2 = 13.504, P <0.05). The median Pu’er tea before 2010, (90) is higher than that of Pu’er tea produced in 2010-2015; the rare earth residues of Pu’er tea produced before 2010 are higher than that of Pu’er tea produced in 2010-2015 (Mann-Whitney U = 5 758.000, Wilcoxon W = 18 638.000, Z = 4.226, P <0.05). From the distribution range, rare earth residues in Pu’er tea are mainly distributed in the range of 1.0-3.0 mg / kg. The distribution of rare earth residues in Pu’er tea produced before 2010 is higher than that of Pu’er tea produced in 2010-2015. Conclusion There are differences in the residue of Pu-erh tea in different years. The problem of rare-earth residues in Pu-erh tea produced in 2010-2015 is better than before 2010.