The effects of different storage conditions (temperature and period) on quality of Matcha have been studied by measuring the contents of chlorophyll and its derivatives, total vitamin C, the surface color value and the amount of oxygen in tea bag. Sensory test was used at the same time.
As a result, it was found that the preservation of Matcha under low temperature (-70 and 4°C) kept its quality in good conditions during 24 weeks. Furthermore, the preservation at room temperature (25°C) kept the quality in the moderate conditions during 24 weeks. However, at the higher temperature of 37°C, the quality of Matcha resulted in fairly bad in 3 or 4 weeks. The cause of the changes in quality should be related to the decrease of the amount of oxygen in tea bag at the higher storage temperatures.

View full abstract

1. When tea trees were covered with white non-woven polypropylene fabric forming a tunnel in winter, the daily highest temperature in the covered part was 8 to 11°C higher than the uncovered part, while little difference was observed in the daily lowest temperature between these parts.
2. The free amino acid content in new shoots in the covered part was significantly higher than that in the uncovered part. Significant difference was not observed in the total nitrogen content between these parts.
3. The number of new shoots developed in the covered part was lower than that in the uncovered part. Both the weight of new shoots in a predetermined area of 400cm2 and the weight of 100 new shoots in the covered part were lighter than those in the uncovered part.
4. Between the covered part and the uncovered part, significant difference was not observed in either the free amino acid content in fibrous roots or the rate of photosynthesis in mature leaves.
5. The free amino acid content in new shoots in the covered part was relatively higher than that in the uncovered part. It is estimated that the poor growth makes the covered part richer in amino acids.
6. Effective length for covering was estimated at 1.5 months to increase the content of amino acids in new shoots. Prolonging the covering period did not result in any further increase of them.

View full abstract

The hygienic maintenance of food has become an increasingly important issue in recent years. This is true in the tea industry as well.
In the present study, we investigated the amount of microorganisms in incoming lots of crude tea (green tea). Crude tea contains large amounts of microorganisms in comparison with oolong tea and black tea, ranging most frequently from 3×10 3 CFU/g to 1×10" CFU/g. In oolong and black teas, the amount of microorganisms most frequently ranges below 3×101 CFU/g.Differences attributable to the crop year, harvesting season and a location of the plants have been neglected. We have found, however, a difference in the amount of micro-organisms with two types of steaming machine: a net drum type and a conveyor type.The amount of microorganisms in crude tea from the conveyor type tends to be greater than that from the net drum type.
We also investigated the quantity of microorganisms in the samples from each process stage of the plant.At the stage of fresh leaves, the amount of microorganisms in the tea sample was about 1×106 CFU/g.In tea processed in net drum type steaming machines, that was decreased to the range of 102.103 CFU/g.In tea processed in conveyor steamers, however, the amount was decreased to only 10 5 CFU/g.In late stage tea plants, the amount of microorganisms in the sample was increased, and the final amount of microorganisms in the crude tea was in the range of 102-104CFU/g. It is presumed that two main causes on the large amounts of microorganisms in crude tea are the survival of these microorganisms in the steaming stage and the secondary contamination from late stage of plants.

View full abstract

Oxalaic, citric, malic, succinic and phosphoric acids in green tea leaves and tea infusions were analyzed by using capillary electrophoresis. We also measured the contents of these organic acids in new tea shoots at different growth stages and in different parts of shoots. We concluded that citric acid might contribute to the sweetness of green tea while organic acids are less important as the indicators of the quality than total nitrogen or theanine. The contents of soluble and total oxalaic acid in shoots were less in tea leaves grown in the low nitrogen supplied field.

View full abstract

Two tea clones, 'KNA F213' and 'KNA KOREA 93-23-7', that have flowers with stamens divided into clusters were found in germplasm of the National Institute of Vegetable and Tea Science. 'KNA F213' was developed from 'Yabukita' x 'Houryoku', and 'KNA KOREA 93-23-7' was collected from the precincts of Man Yeum Sa Temple in Korea. The filaments in these two clones adhere to each other. The pollen fertility of both of the clones is high. It is thought that this flower type is a genetic characteristic, but the mode of inheritance is not clear.

View full abstract

Sodium ion concentrations in green tea leaves have been used for an index of discriminating monosodium glutamate added tea.
However, in tea leaves produced at the sea-side area these values often exceeded the critical level which was proposed previously as a kind of standard. There are significant differences in the concentration of sodium ion respectively among the sea-side area, the hinterland and the middle area. It was considered that the high values of sodium ion concentration of tea produced at the sea-side area were caused by attachment of splashed sea water to tea leaves with wind. Those values were notably reduced after rain.

View full abstract

Inorganic elements in tea leaves (Camellia sinensis cv. Yabukita) were investigated using an X-ray fluorescence (XRF) microscope analyzer. The pixcel-intensitities from XRF images of potassium in new buds were higher than those in mature or immature leaves. The calcium content was higher in mature leaves than in immature leaves, especially in petiol.
The distribution of the inorganic elements was changed by the infection of tea anthracnose (Colletotrichum theae-sinensis (MIYAKE) YAMAMOTO). While calcium was accumulated at the lesion point, potassium was decreased as the progress of disease. XRF microscope analyzer lead to simple, nondestructive and simultaneous element analysis in tea leaves. It will be useful for elucidation of response mechanism for physiological disorder or damage by disease and pest based on elements dynamics.

View full abstract

A new method using high performance liquid chromatography was developed to analyze the concentrations of adenylic, inosinic and guanylic acids in green tea infusions. Both adenylic and guanylic acids were found in tea infusions, however the concentrations of them were too low to enhance umami taste. Some teas are flavored with umami seasonings. In the infusions of seasoned green teas, the concentrations of guanylic acid were higher than those in unseasoned (natural) teas. Moreover, inosinic acid was often found in the infusions of seasoned teas. This analytical method can be applied for the discrimination of seasoned teas.

View full abstract

Zoning of tea field by climate characteristics is widely used among both scientists and farmers without precise definition. We here proposed a new concept for precise zoning, which is based on monthly average of daily minimum temperature in the coldest month at each the third mesh, which is a square of about 1km sides. This may be the first application of mesh data for culture field zoning. We also define new zones, namely, limiting zone, death zone, subtropics, as well as well-known ones, warm zone, temperate zone, and cool zone. The resulted zone map will be open to public by WWW after the publication of this paper. One of this map's pixel is equivalent to one mesh. Using this character, we can judge zone definition of a point on the map. Such reusable and precise point definable zone map was not known. Using this approach, we simulated global warming simply raise the temperature of each mesh to additional 2°C, 4°C, 6°C and zoning land. This result shows intensive expansion of subtropics area among southern Japan, and urgent establishment of culture system in this area should be done.

View full abstract

A program was developed in order to calculate the score of tea evaluation rapidly in tea competitions. This program enables efficient input with keyboard, accurate ranking and printing in a desired format. This program is so flexible that it can be used for ranking in any tea competition which has different rules.

View full abstract

Gyokuro, high-grade green tea, contains a lot of amino acids. Umami is a very impor-tant taste for such high-grade teas. Amino acids and organic acids were analyzed in Gyokuro tea infusions. The model solution that imitates umami taste of the Gyokuro infusions was prepared according to the analytical data. It was estimated that glutamic acid, theanine and citric acid are important for umami taste of Gyokuro as results of the organoleptic omission tests from the model solution.

View full abstract