Tea leaf extraction, esp. for instant tea prodn. - using aq. soln. contg. ammonium bicarbonate or ammonia to increase soluble solids yield

摘要

Solids are extd. from tea-leaves with an aq. soln. of NH4HCO3 oR NH3. In counter-current extn., yield may be increased by adding NH4HCO3 or NH3 in penultimate step of a multi-step process, before tea-leaves leave the system. Extn. temps. may be 50-200 (100) degrees C. Water : tea-leaf wt. ratio in extn. may be 5 : 1 to 25 : 1. Process can be used for extn. of (i) fresh-, (ii) fermented- or (iii) spent tea-leaves. Extract can be spray-dried to prepare an instant tea-powder. Addn. of NH4HCO3 or NH3 to the water increases soluble solids yield by >=30% and quantity of non-tea residue is negligible.