Essential and Non-Essential Elements Analysis in Black Teas and their Extraction Efficiency using Neutron Activation Analysis

This study aims to evaluate the concentrations of essential (Na, K, Mg, Fe, Zn, Co, Mn, Cr) and non-essential (Al, Ba, Rb, Br, La, Sc, Sm) elements in black tea leaves and their infusions. Additionally, it investigates the extraction efficiency of these elements to assess their dietary contributions, particularly for populations of Iran with high tea consumption. Neutron activation analysis (NAA) was employed to determine elemental concentrations in five popular black teas commonly consumed in Iran. The analysis quantified the transfer of elements from dry tea leaves to tea infusions, calculating extraction efficiencies to assess their potential dietary relevance. Elements with high extraction efficiency (>55%) included Rb (79.3%), K (78.7%), Br (65.9%) and Cr (61.3%). Moderate extraction efficiencies (20-55%) were observed for Co (32.4%) and La (20.6%), while poor extraction efficiencies (<20%) were noted for Mg, Ba, Zn, Sm, Na, Al and Sc. Black tea was identified as a dietary source of trace elements such as Cr, Rb and Co, highlighting its potential nutritional value for high-consumption populations. This study provides novel insights into the elemental composition and extraction efficiency of black tea, emphasizing its role as a dietary source of essential and trace elements. The findings have significant implications for understanding the nutritional contributions of tea in regions with high consumption, particularly in Iran, where tea is a staple beverage.