Application of far-infrared irradiation in the manufacturing process of green tea.
Seven kinds of green tea leaves were manufactured with far-infrared (FIR) irradiation, and the physicochemical characteristics of the green tea were determined. Appropriate FIR irradiation during the manufacturing process significantly increased the polyphenolic content of green tea. FIR irradiation at 90 degrees C for 10 min, replacing the roasting step, and of the fully processed green tea leaves (GTP3) increased the total phenol content of green tea from 475.6 to 811.1 mg/g and the total flavanol content from 175.7 to 208.7 mg/g, as compared to the control. Epigallocatechin and epigallocatechin gallate increased from 57.68 and 9.60 mg/g in a nonirradiated control to 89.88 and 16.33 mg/g in GTP3, respectively. Ascorbic acid, caffeine, and nitrite scavenging activities were also increased in GTP3. However, the overall color change of GTP3 was negligible. These results indicate that the chemical properties of green tea are significantly affected by FIR irradiation at specific stages of the manufacturing process of green tea leaves and that this FIR irradiation results in high-quality green tea.
Kim
So-Young
SY
Department of Food Science and Biotechnology, Kyungnam University, Masan 631-701, Korea.
Jeong
Seok-Moon
SM
Jo
Seong-Chun
SC
Lee
Seung-Cheol
SC
D001205:Ascorbic Acid / Q000032:analysis; D002110:Caffeine / Q000032:analysis; D028241:Camellia sinensis / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives / Q000032:analysis; D044948:Flavonols / Q000032:analysis; D005511:Food Handling / Q000379:methods*; D016166:Free Radical Scavengers / Q000032:analysis; D007259:Infrared Rays; D010636:Phenols / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry; D013662:Tea / Q000737:chemistry*
D044948:Flavonols; D016166:Free Radical Scavengers; D010636:Phenols; D013662:Tea; D002110:Caffeine; D002392:Catechin; C057580:gallocatechol; D001205:Ascorbic Acid