Application of Enzymes in the Production of RTD Black Tea Beverages: A Review

Ready-to-drink (RTD) tea is a popular beverage in many countries. Instability due to development of haze and formation
of tea cream is the common problem faced in the production of RTD black tea beverages. Thus decreaming is an important
step in the process to meet the cold stability requirements of the product. Enzymatic decreaming approaches overcome
some of the disadvantages associated with other conventional decreaming methods such as cold water extraction, chill
decreaming, chemical stabilization, and chemical solubilization. Enzyme treatments have been attempted at three stages of
black tea processing, namely, enzymatic treatment to green tea and conversion to black tea, enzymatic treatment to black tea
followed by extraction, and enzymatic clarification of extract. Tannase is the most commonly employed enzyme (tannin acyl
hydrolase EC 3.1.1.20) aiming at improving cold water extractability/solubility and decreasing tea cream formation as well
as improving the clarity. The major enzymatic methods proposed for processing black tea having a direct or indirect bearing
on RTD tea production, have been discussed along with their relative advantages and limitations.