Detection of optimum fermentation time for black tea manufacturing using electronic nose

Fermentation is an extremely crucial process in black tea manufacturing and is primarily responsible in deciding the final quality of finished tea. During this process, green tea changes its colour from green to coppery brown and grassy smell gets transformed to floral smell. A complex chain of biochemical reactions takes place during the fermentation process and once such changes reach their optimum point, the process should be stopped. The quality of the final product hinges to a large extent on the decision to end fermentation at right time, and either under-fermentation or over-fermentation leads to deterioration of finished tea quality. This paper presents a study on electronic nose-based monitoring of volatile emission pattern during black tea fermentation process and detection of the optimum fermentation time on the basis of peaks in the sensor outputs. (c) 2006 Elsevier B.V. All rights reserved.