Effect of far-infrared irradiation on catechins and nitrite scavenging activity of green tea.
The processed green tea leaves were irradiated by far-infrared (FIR) at eight temperatures (80, 90, 100, 110, 120, 130, 140, and 150 degrees C) for 10 min. After FIR irradiation, green teas were prepared by soaking the leaves in boiling water, and the physicochemical characteristics of the green tea were determined. FIR irradiation at 90 degrees C increased total phenol contents of green tea from 244.7 to 368.5 mg/g and total flavanol contents from 122.0 to 178.7 mg/g, compared with non-irradiated control. FIR irradiation also significantly affected the amounts of epigallocatechin and epigallocatechin gallate. Nitrite scavenging activity also increased with increasing FIR irradiation until the temperature reached 110 degrees C. However, the overall color changes of green tea irradiated with FIR at 90 and 100 degrees C were negligible. These results indicate that the chemical quality of green tea is significantly affected by FIR irradiation temperature of the green tea leaves.
Lee
Seung-Cheol
SC
Division of Food Science and Biotechnology, Kyungnam University, Masan 631-701, Korea. sclee@kyungnam.ac.kr
Kim
So-Young
SY
Jeong
Seok-Moon
SM
Park
Ji-Hee
JH
D002110:Caffeine / Q000032:analysis; D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000032:analysis*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry; D044948:Flavonols / Q000032:analysis; D016166:Free Radical Scavengers / Q000032:analysis / Q000737:chemistry; D006358:Hot Temperature; D007259:Infrared Rays; D009573:Nitrites / Q000737:chemistry*; D010636:Phenols / Q000032:analysis* / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry / Q000528:radiation effects*; D059808:Polyphenols
D005419:Flavonoids; D044948:Flavonols; D016166:Free Radical Scavengers; D009573:Nitrites; D010636:Phenols; D059808:Polyphenols; D002110:Caffeine; D002392:Catechin