Assessment of heavy metals in black tea produced in different agro-ecological regions of sri lanka

Abstract

Ceylon tea is famous throughout the world for its unique taste. Over 95 % tea produced in Sri Lankais exported. In recent times many tea importing countries have either changed or in the process of changing their food safety laws, generally resulting in lower limits for heavy metals.Tea is generally regarded as safe (GRAS) and was not included in random monitoring programmesat the point of entries to those countries in the past. However, recently in many countriesGRAS food items are also subjected to the random monitoring process. Thus, it is I importantthat base line levels of heavy metals for different types of Sri Lankan black teas are fe-establishedand precautionary measures are taken to ensure that Sri Lankan tea complywith thesenew regulations. Heavy metals in black tea could change due to various factors and one of the main factors is the Agro-ecological region they grow. There are eleven main Agroecologicalregions and the quality of the made tea produced is different trom region to region. In thisstudy, an attempt was made to understand the natural level of heavy metals in black tea producedin different Agro-ecological regions and their variation among regions. Further, metalswere analysedto establishbase line values. Thirtyfive factories were selected from different Agro-ecological regions of Sri Lanka. Black tea (BOPgrade) was analysed for the heavy metals namely, copper, nickel, cadmium and iron. Atomicabsorption spectrophotometry was used as the analytical technique to analyse the metal content in black tea. AOAC Official Methods of Analysis were followed as the analyzingprocedure. Further, compliance of the sample with ISO 3720, specifications for blacktea was also verified. Copper content in black tea was well below the Sri Lankan Limit of 100 ppm in all regions. It wasfound tha t copper content was below 40 ppm. Nickel content in black tea was below 8 ppmin all regions. Cadmium content was below 0.2 ppm. The current Sri Lankan Standard is also0.2 ppm. Iron content in black tea was well below the Sri Lankan Limit of 500 ppm. It wasfoundthat iron content was below 300 ppm. Copper, nickel and cadmium content in black tea did not significantlychanged with Agro-ecological region. However, iron content in black teahas a significantvariation within Agro-ecologicalregions.