Simple Methods of Judging the Qualities of Black Tea for Individual Selection Work in the Tea Plant Breeding (Part 3)

Some Considerations on the Raikai Tea Manufacturing

Abstract

The Raikai tea manufacturing (tea leaves are ground and kneaded in Raikai-machine) is considered the most important method used in judging the qualities of black tea for individual selection work in the tea plant breeding.
This method is superior to the orthodox one for the following reasons: The processes are simple and need a small quantity of sample to be tested.
Recently, Ishikawa's No. 18 Raikai-machine is used, but the optimum manufacturing conditions for this machine are unknown.
Using six tea varieties (Assam varieties, China varieties and Assam hybrids), the influences of the manufacturing processes on the qualities of black tea were investigated under six degrees of withering (0%, 10%, 20%, 30%, 40% and 50%) (percentage shows the loss of weight), three levels of Raikai time (7 min., 13 min., and 20 min.) and four levels of fermentation time (1 hr., 1.5 hrs., 2 hrs. and 3hrs.).
The results showed that the qualites of the Raikai manufactured tea seemed to be much influenced by the manufacturing condition in each process.
The optimum direction for use of the Ishi-kawa's No. 18 Raikai-machine was determined as follows : The degree of withering was 30%, the Raikai time was about 13 min. and the fermentation time was about 2 hrs.
The above conditions seemed to vary somewhat according to the nature of the leaf of r the used variety.
It was also indicated that the high positive correlations were observed between the qua-lities of black tea made by the Raikai method and the orthodox one.
From the above results, it was concluded that the standard Raikai tea manufacturing was very useful as a simple method of judging the qualities of black tea for the individual selection, the clone test and the test of adaptability in the tea plant breeding.