Effect of Shaping Methods on the Quality of E-Cha No. 10 Green Tea Products

Purpose This study was performed to explore the effect of shaping methods on the quality of green tea products.

Method The high quality fresh leaves of E-Cha No.10 were processed into bud-shape, flat-shape, strip-shape and needle-shape green tea respectively. The sensory quality of samples was graded and the chemical compounds of samples were analyzed by spectrophotometer method, colorimeter method, high performance liquid chromatography and gas chromatography mass spectrometry.

Result Compared with the other shaped green tea, flat-shaped green tea was of highest quality, which was implied from the lowest content of polyphenols, the highest content of amino acids, the lower bitter and astringe index of catechin for taste, and the most abundant volatiles with floral and chestnut-like aroma. Moreover, compared with the needle-shaped green tea, the flat-shaped green tea had higher contents of total chlorophyll, larger value of L^*, b^* and b^*/a^* of appearance, and the smaller value of a^* of both appearance and infusion, contributing to more concordant green color of flat-shaped green tea. Additionally, it was considered that bud-shape green tea was slightly inferior to the flat-shaped green tea in terms of comprehensive quality despite of the higher color quality. Results also showed that although the needle-shaped green tea had the merit of strongly floral and chestnut-like aroma, its color was yellowish and taste was more bitter and astringe.

Conclusion Processing E-Cha No.10 leaves to flat shape not only improved the quality of taste and aroma, but also the appearance was well-guaranteed. Therefore, this study demonstrated that the flat-shape green tea of E-Cha No.10 was best of comprehensive quality.