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Riwaka:
Department of Scientific and Industrial Research. (The
research arm of the Motueka venture)
Trials at Riwaka were set up initially by the founder of the
Motueka Co-op but the Japanese were in it from the start and
it was they who pulled the plug on the trials in the finish.
The Riwaka trials put in 1,200,000 cuttings and it took 5
years to the first pluck. Time from cutting-strike to
planting out compared well to Japanese yardsticks. Cuttings
were kept in a shed and treated with seradix hormone, then
planted direct into the ground. The cuttings were undercut
with machine with very few losses, and tops were trimmed to
20 cm. The bed width was 1.8m and there was 8-9” between
plants. The variety used was a clone of Yabukita put in at
18,000 to the ha. Scale insect was controlled with Supracide.
High pH is a problem to some varieties but, if calcium was
needed, this was supplied via gypsum. (JJ – have I got that
bit right??) Phytophora is a problem in high rainfall –
Riwaka gets 1200 mm p.a. Frost problems might have been
overcome had 2 x 10 metre high fans been installed, but
local planners would not allow this. Because of ozone
depletion New Zealand does not suffer from frost pockets in
the same way as the UK, but equally day time heat will
evaporate more rapidly than it does in a northern hemisphere
climate.
Harvesting was carried out with a single row harvester. The
crop was put into 80% shade for 5 days before harvest. There
were 2 cuts per year, up to 50 days apart, but the first had
by far the better quality.
The time from harvest to factory was less than 4 hours. The
factory process consisted of a series of heating and curling
operations according to the authority Takeo. (His book is
entitled Tea: Cultivation to consumption: green and
fermented tea. Chapter 13 pp 413-457. (eds K C Willson and M
N Clifford) published by Chapman and Hall in 1992).
Takeo states that plucked leaves are steamed for 45-60
seconds, then curled and dried in hot air at 90-110oC for
40-50 minutes. This primary drying and rolling process
reduces moisture content from about 76% to 50%. Leaves are
then rolled for a further 15 minutes without heat and then
pressed and dried for 30-40 minutes in hot air at 50-60oC.
This secondary drying reduces moisture content to about 30%.
A further curling is followed by the third drying stage at
which leaves are dried directly on a hot pan at 80-90oC and
twisted for 40 minutes under pressing and rolling by a
curling hand mounted on a fan.
Finally the tea leaves are dried at 80oC until a moisture
content of 6% is achieved. This results in a fine needle
like form of sencha (type of Japanese green tea product).
Final cleaning and grading to remove dust and stalks then
takes place. The product needs vacuum packing for export. |
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