Effect of batch extraction conditions on yield of soluble solids from rooibos tea

Summary Extraction of soluble solids from rooibos tea (Aspalathus linearis) was investigated by single stage batch extraction. The effect of extraction temperature, extract: tea mass ratio and flow rate of water on extract concentration and yield of soluble solids was determined. Extract concentration and yield increased linearly with increase in temperature from 23 to 90°C. Increasing the mass ratio from 5:1 to 10:1 decreased extract concentration, but increased yield. Both extract concentration and yield decreased with an increase in flow rate from 0.1 to 0.2 m3/hr. The water‐soluble solid content of rooibos tea leaf was 21.74%, 75.1% of which was extracted at 90°C, mass ratio 10:1 and flow rate 0.1 m3/hr.