Selected Inorganic Nutrients in Black Tea from Three Tea Growing Agro-Ecological Areas in Kenya

Abstract

The tea plant absorbs dissolved nutrients from soils for its normal growth and development, though to different extents. Nutrients play vital roles in various metabolic processes, their deficiency or excess being deleterious to living organisms. A study was carried out to quantitatively assess the inorganic nutrient content (K, P, Ca, Mn, Fe, Zn and Cu) of twelve black tea samples sourced from Murang’a, Meru and Kisii tea growing agro-ecological areas in Kenya. K and P were quantified using a flame photometer and a UV-Vis spectrophotometer respectively whereas Ca, Mn, Fe, Zn and Cu were quantified using an Atomic Absorption Spectrophotometer (AAS). The general accumulation pattern of the inorganic nutrients in the tea samples was established to be; K (1.6% ± 0.05% - 2.1% ± 0.01%) > P (0.30% ± 0.01% - 0.37% ± 0.04%) > Ca (0.16% ± 0.01% - 0.62% ± 0.03%) > Mn (0.07% ± 0.009% - 0.13% ± 0.004%) > Fe (136 ± 8 - 320 ± 5 µg/g) > Zn (27 ± 1 - 39 ± 7 µg/g) > Cu (10 ± 3 - 16 ± 1 µg/g). Statistically significant differences (p < 0.05) were observed in the inorganic nutrient contents of the black tea from the different tea factories as well as agro-ecological areas. These data demonstrate the tea plant’s ability to accumulate the studied nutrients, further underlining tea consumption as a potential dietary source of the nutritionally essential inorganic nutrients.