Factors affecting the production and quality of partially fermented tea in Taiwan

Supply and demand is one of the most important factors determining of Taiwan tea production. Historically, production of Taiwan tea was primarily for export. Oolong tea was the most important tea exported initially, but it was replaced by black tea and then by green tea. Recently in Taiwan, due to a sharp increase in production costs of tea, we have lost substantial markets, and the production of partially fermented Chinese tea for domestic consumption has become more important. Both the tea plantation area and tea exports have decreased. However, the amount of total tea production has been fairly well maintained because of a gradual increase in tea yield per unit area as a result of progress in culture technology and variety improvement. Currently, 23 000 m.t. of tea are produced from 23 000 ha of tea plantation. The quality of tea is affected by a number of factors which can be classified under 4 major items, namely cultivars, environment, cultural practices and tea processing techniques. Cultivars: The fermentation ability, chemical components and agronomic characters vary with cultivars. For partially fermented tea, quality is more important than yield. Environments: Soils and climate are two major factors affecting the quality. High elevations are considered to be the most favourable for production of quality tea. Cultural practices: These, including tillage, weeding, fertility management, irrigation, plant protection and harvesting management may affect the quality though their effect on the yield may be more important. Among the management practices affecting the quality, leaf age and season of harvesting are the most significant. Processing technique: The processing technique of partially fermented tea involves a series of complicated operations (withering, shaking, panning, rolling, and drying) which, indeed, can be regarded as an art. Slight changes in manipulation of every step can affect the final quality including appearance, tea liquor colour, aroma and taste. It is not surprising to find that the qualities of made teas from the same batch of fresh leaves may vary greatly between individual processors.