An Improved Method of and Means for the Drying of the Leaves of Tea and other Plants.
Year: 1892

page_text: Date of Application, 1st Nov., 1892-Accepted, 3rd Dec., 1892
COMPLETE SPECIFICATION.
An Improved Method of and Means for the Drying of the Leaves of
Tea and other Plants.
I, LIONEL MAYNARD TORIN of 98 Sloane Street, in the County of London,
and of Aldourie Estate, Agrapatna, Ceylon, Tea Grower, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
My invention relates to an improved method of and means for the drying of
the leaves of tea and other plants.
The object of my invention is to effect the said drying in a more expeditious,
cheaper, and more effectual manner than has been done hitherto, also to reduce
the risk of spoiling the leaves by carelessness or inattention of the attendant, so that
the resulting product has a much stronger and better flavour for reasons more fully
hereinafter described.
Up to the present time the method usually adopted for drying the leaves of tea,
has been that in which hot air is caused to pass over, or be drawn through, the tea
which is generally spread upon trays. Under this particular method of treatment
the tea is liable to be over-fired, burned, or smoked, and all the volatile constituents
of the tea are apt to be carried off, owing to the great difficulty of exactly
regulating the temperature, and thus much of the strength and flavour of the tea
is lost.
My invention consists in drying the tea or other leaves in a closed chamber
under the influence of a vacuum, and applying the heat for evaporation by the
medium of steam.
To carry out my invention I place the tea leaves to be dried in a vacuum pan
and apply heat to the exterior surface of the pan by surrounding it with, or
bringing into contact with it, steam of any desired pressure according to the degree
of temperature desired.
The tea is placed into the pan in bulk and kept from packing by agitation or by
a mechanical stirring arrangement disposed within the pan.
The vacuum within the pan can be created and maintained by the action of an
air pump or other exhausting appliance.
Under the influence of the vacuum the evaporation of the superfluous moisture
takes place at a very low temperature comparatively which prevents the leaves
becoming crisp.
Water being the most volatile of the constituents of tea, it will be first evaporated
and the essential oils would be retained.
The time of operation and temperature of the process of evaporation must be
varied according to the nature of the leaf, the resulting flavour desired, and the
external atmospheric conditions, the desired object being to carry off the water,
without affecting the less volatile oils.
It will be quite obvious that by drying the tea in a vacuum pan, it will be
impossible to burn or smoke the tea, and the risk of over-drying will be reduced
to a minimum, as the temperature is regulated by the pressure of the steam which
can be easily controlled so as not to exceed a given amount.
The leaf would by this process remain soft and leathery as compared to the tea
which has been air-dried as in the process at present carried out.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1st. An improved process for drying the leaves of tea and other plants consisting

page_text: of the treatment of the leaves within an hermetically closed chamber within which
a vacuum is maintained beat being applied to the said chamber through the medium
of steam.
2nd. In an improved process for drying the leaves of tea and other plants in
which the leaves are dried in an hermetically closed chamber under a vacuum and
heated by any suitable means such as steam; an agitation or stirring of the leaves
during the process of drying, to prevent packing, substantially as described.
Dated this 1st day of November 1892.
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.