Rural Industries Research & Development Corporation

The New Rural Industries
A handbook for Farmers and Investors

Japanese green tea

Introduction

Green tea belongs to the group of flowering plants termed Camellias, mostly used as garden ornamentals. Camellia sinensis is one of two subspecies used in tea production world-wide. The three varieties Sayamakaori, Yabukita and Okuhikari are currently being tested in Australia.

Green tea has been propagated from plants originally brought through quarantine from Japan. The experience in Australia has been similar to that of New Zealand in that high mortalities resulted from the fumigation treatment with methyl bromide to prevent the entry of Kanzawa mite and other pests into Australia. The surviving plants have been successfully propagated to increase the supply of plants for various trial plantations around the nation.

Green tea planted in Tasmania is now entering its fifth year. The crop is a perennial and is not regarded as mature until it has been established in the field for five years. There have been difficulties, which include a lack of suitable soil types, climate and frost damage. Trials have been established in the north-east and a further site is to be planted in the south of the state. During the pruning, which sets up the plucking table for the first flush and harvest, minor wind and frost damage is removed. The plants then flush and this new growth is removed for processing into green tea.

Markets and marketing issues

Demand for green tea is increasing world-wide because of interest in its medicinal value. There has been a large market throughout Asia for the different forms of green tea and it plays an important role in traditional diets. The range of green-tea types and qualities available in the Asian area varies from a form known as gunpowder to the very high quality ceremonial teas only used on special occasions.

Japan's own import of green tea is growing while its exports are decreasing. The trend in Japan is to value-add to green tea. Green tea can be used as an ingredient in ready-to-drink teas, soft drinks, ice cream, biscuits and lollies. The human health issues are also gaining popularity: green tea has been linked to cancer prevention and to anti-ageing effects.

There is very little information available on the newly-emerging green-tea industry in Australia as there are no traditionally processed green-tea sites at a commercial stage. Information on other markets around the world can be patchy. Japanese production peaked in the early 1980s with 61,000 ha and this has undergone a slow reduction since then of around 8%. 1993 saw a production of 420,200 tonnes of raw leaf produced - over 30,000 tonnes less than in the early 1980s. The highest yield/ha of green leaf is 9.2 (1993). The highest yield of made green tea was 2,251 kg/ha, and the lowest yield was 664 kg/ha. Prices paid for fresh leaf at the farm gate vary from farmer to farmer, through the season and between years. There are generally three harvests per season with the first harvest in Japan being the best. Average prices range from $26.00 to $33.00 per kg of green leaf. The prices can vary as many as nine times from the first harvest to the last harvest.

Production requirements

Green tea in Australia is in the later stages of testing. A large amount is known about its agronomic requirements. The new flushes of green tea are harvested. Only the soft lush growth is taken and this generally consists of the topmost bud and the next two or three leaves. The first flush, usually in November in Australia (slightly earlier in more northerly areas), is generally thought to be the highest quality and is also susceptible to late frosts. Site selection is very important in planning a green-tea planting.

Good drainage of soil water and cold air is very important to prevent water-logging and the pooling of cold air around the plants. Wind damage can drastically lower the quality of tea that is produced. The best aspect would be a northerly facing, gently sloping site with good drainage and protection from wind.

Green tea develops a strong deep root system with some surface-feeding roots. As the bushes mature they spread out and crowd out most weeds. Before the canopy matures, they can suffer weed competition, root damage from excessive tilling between the rows and from lack of moisture. Moisture is also essential to move fertilisers through the soil so that the plants can use it.

Varieties

Of the three varieties at present in Australia (Sayamakaori, Yabukita and Okuhikari) 80% of Japanese plantings are of the variety Yabukita, which tends to be higher quality after processing although Sayamakaori yields are higher in colder climates.

Green tea is produced from clonal material by cuttings. The DPIF is continuing to acquire germplasm for other varieties that may prove suitable for the production of green tea in Australia and for the range of climate types available for agriculture.

Agronomy pest and disease control

Green tea came from Japan where there is an extreme pest problem. Before they were established in field trials, plants were quarantined for a period of 18 months. This extended quarantine period was necessary to disinfest plants of Kanzawa mite (Tetranychus kanzawa), an exotic species of mite found on the plants during the quarantine period. The plants were then disinfested by fumigation with methyl bromide.

There are currently no pesticides in use on the green tea in the DPIF plantings.

Harvesting, post-harvest treatments and processing

Green tea can harvested by hand or by mechanised harvesters which are either hand-held or mounted on modified tractors. Hand picking produces the highest grades of final product although the labour costs are very high. Two-man harvesters are efficient in small areas and are reasonably priced, fully imported to Australia, at around $3,000. A mounted tea-harvester is made in Australia (North Queensland) and can be made with various widths of cutter bars, with the machine itself mounted on tracks.

Processing equipment has been designed and made in Japan for traditionally made teas and reflects the traditional hand processing. The processing is quite involved, with various stages of drying and rolling. The difference between green and black tea is essentially one of processing. The fresh leaves are steamed to denature the enzymes which would normally be active after picking and would turn the tea into black tea.

The first stage in processing is the steaming machine. Steaming denatures polyphenoxidase enzymes to prevent subsequent oxidative fermentation of the leaf flavenols. It is these flavenols which produce the polyphenols giving the colour, aroma and the mouth-feel typical of black tea. The steaming prevents fermentation almost instantaneously and it is this process that retains the bright green colouration typical of Japanese green teas. This process, which lasts for only 45 to 60 seconds, reduces the water content of the leaves to 75%. The

leaves are then transferred to the primary drying tea-roller which twists and dries them at temperatures of around 90-110ºC for 40-50 minutes. The process further reduces the water content to 50%.

Leaves are transferred to the secondary drying tea-roller which presses and twists the leaves, breaking up their cells and producing an even distribution of water content. This roller is heated to 60ºC and has rolling hands which dry and roll the leaves to produce the characteristic shape and aroma of green tea. The tea is then transferred to a tea drier which reduces the water content to between 13 and 6%.

A batch plant that can process 2kg of fresh leaf costs up to (installed) $120,000. According to figures from Japan, to process 40 ha of tea plantation costs between $3 and 5 million.

Economics of production

The green tea crop is perennial and is not regarded as mature until it is five years old. Capital costs include fencing, plant and equipment, irrigation, mulching, planting by hand, windbreaks and plants at 18,000 per hectare costing $14,400. The initial cost of the processing equipment is the highest as previously stated.

After modelling the production, and basing the figures on optimistic yield figure prices, the top table (not available in this html version) shows figures for dry weight production.

The effects of a 10% and 20% increase and decrease of first and second cut tea yield are shown in the lower table (not available in this html version). A 10% reduction in yield results in the enterprise becoming an unattractive investment.

Key contacts

Key References

Monks, A.J. and Baxter L.B. To continue the investigation into commercialisation and development of Japanese green tea, Camellia sinensis. Final report RIRDC project number Dat 24A.

Wilson, K.C. and Clifford, M.N. 1992 Tea cultivation to consumption. Chapman and Hall.

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