Effects of Roasting Condition on the Qualities of Roasted Green Tea (Hojicha)

Abstract

The effects of roasting conditions on the qualities of roasted green tea were investigated employing a laboratory scale roaster capable to regulate the temperature. As the results of sensory test, it was found that the roasted tea of the most favorable quality was obtained when roasted at 160-180°C.
The loss of tannin, water extract, and ascorbic acid in green tea was remarkable during roasting, especially the loss of ascorbic acid amounted to the half of the green tea when roasted at the best conditions. The results of paperchromatography noted that the principal flavanols such as epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate were decreased remarkably in amount and new constituents of phenolic compounds were produced.