Instrumental evaluation (Infra-red)

Generally, the quality of tea is evaluated by sensory test. However, skilled judges might be affected by their conditions and the standard may not be uniform. Recently, the apparatus, measuring the irradiation of infra-red rays from tea when they are emitted to tea, has been practically introduced to study the components and quality of tea. The theory of the apparatus is based on the close relationship between the absorption of light in infra-red and the kind and amount of component of tea. Infra-red in not harmful and is easy to measure even for people with no experience. This apparatus is able to determine the amounts of moisture, fiber, total nitrogen, caffein, catechins, amino acids, theanine, and vitamin C. The quality of tea is estimated from the amount of each. This method is used to evaluate the raw materials and component analysis and quality evaluation of crude tea and refined tea. The studies of quality evaluation using instruments are underway: shape by image analysis equipment, color by pigment measure, aroma by gasgromatgraphy(GC), taste by liquid-cromatgraphy (HPLC). Although those methods still need improvement because they are time consuming and they need specialists' skills and analysis, new instrumental evaluation that can sense just like human senses and that can evaluate the quality synthetically will soon be developed.