PROCESS FOR MANUFACTURING A LEAF TEA PRODUCT
The present invention relates to a process for manufacturing a black leaf tea product, the process comprising the steps of: providing black leaf tea having a moisture content of less than 5 wt. %; and then subjecting this black leaf tea starting material to a heat treatment step by contacting it with a heated surface at a temperature of 100° C. to 170° C. for a duration of 2 to 25 minutes. The present invention also relates to a black leaf tea product obtainable by this process.
1 . A process for manufacturing a black leaf tea product, the process comprising:
subjecting a black leaf tea starting material, having a moisture content of less than 5 wt. %, to a heat treatment step by passing it through a heated tube and contacting it with a heated surface inside the tube at a temperature of 100° C. to 150° C. for a duration of 3 to 15 minutes,
wherein the heat treatment step is also carried out in the presence of steam, and the steam is provided at a flow rate of about 5 kg per hour to about 10 kg per hour.
2 . The process of claim 1 , wherein the heated surface is at a temperature of 100° C. to 120° C.
3 . The process of claim 1 , wherein the steam is provided at a flow rate of about 5 kg per hour.
4 . The process of claim 1 , wherein the heat treatment step is carried out using a continuous roaster.
5 . The process of claim 4 , wherein the continuous roaster combines vibrational transport and heating via an electrically heated and vibrating spiral tube.
6 . The process of claim 1 , wherein the heat treatment step is carried out in a confined atmosphere.
7 . The process of claim 1 , wherein the black leaf tea starting material is a tea blend.
8 . The process of claim 1 , wherein:
the black leaf tea starting material has an L* value of L* initial ,
the black leaf tea product has an L* value of L* final ,
ΔL*=(L* initial )−(L* final ), and
ΔL* is at least 1.0.
9 . The process of claim 8 , wherein ΔL* is less than 3.5.
10 . The process of claim 1 , wherein:
the black leaf tea starting material has a Normalised Infusion Colour of NIC initial ,
the black leaf tea product has a Normalised Infusion Colour of NIC final ,
wherein Normalised Infusion Colour is expressed in terms of a* value per mg/ml of infusion solids as determined for an infusion liquor obtained by contacting 2 g of the black leaf tea starting material (for NIC initial ) or the black leaf tea product (for NIC final ) with 200 ml freshly boiled water for 2 minutes, and wherein
ΔNIC=(NIC final )−(NIC initial ), and
ΔNIC is 0.3 to 1.7.
11 . The process of claim 10 , wherein ΔNIC is 0.32 to 1.65.
12 . The process of claim 1 , wherein the process comprises the subsequent step of packaging the black leaf tea product.
13 . The process of claim 12 , wherein the black leaf tea product is packaged in an amount of 1 g to 5 g.