CTC Tea Research Articles

Analysis of mineral composition of some Assam and Darjeeling black teas

AbstractBlack teas manufactured in Darjeeling and Assam were analysed for various macrominerals such as P, K, Ca, Mg and microminerals such as Mn, Fe and Cu. A considerable amount of minerals, eg K (40‐46 mg), Mg (2.7‐3.0 mg), Ca (0.48‐0.66 mg) and traces of Mn (0.28‐0.40 mg), Fe (0.16‐0.20 mg), P (29‐41 μg) and Cu (12‐22 μg) were found in a cup of black tea brew. Black teas manufactured from the leaf coming from a pruned section and fine portion usually showed higher mineral content than tea manufactured from unpruned sections and coarse grade teas of Darjeeling. Assam CTC tea was found to be richer in mineral content compared to Darjeeling orthodox tea.

The temperature dependence of the rate of extraction of soluble constituents of black tea

The temperature eVect on the infusion of solubles from black tea leaf was examined by analysing the infusion characteristics of UV active solubles present in the tea leaf by spectrophotometric means. The results represent the Wrst set of kinetic data for extraction of solubles from an Australian CTC tea (Nerada). From the experiments conducted, the activation energy for the infusion of solubles was determined to be 41 kJ mol −1. This value is higher than previous ones in the literature. The results are discussed by comparing them with the temperature dependence for diVusion of species in aqueous solutions. The Wndings are consistent with the likely rate-determining step being the hindered diVusion of a soluble constituent through the leaf matrix.

Comparison of black tea aromas of orthodox and CTC tea and of black teas made from different varieties

AbstractVolatile compounds obtained from orthodox black tea and CTC tea were analysed by a g.c.‐m.s. method. A difference in the contents of cis‐3‐hexenol, linalool, linalool oxides, methylsalcylate and geraniol was found between the two types of tea. It was thought that the difference in the contents of volatile compounds might be produced by the individual manufacturing processes. A typical difference in the contents of linalool and geraniol was observed in volatile oils of black teas made from cultivars of v. assamica and hybrids of assamica and sinensis. The difference in the volatile compounds in black teas may be related to the genetic variation.