Ambient humidification of CTC and CFM room: Its effect on quality of tea

Abstract

During black tea processing, visible changes take place in the oxidation stage. Regulated andcontrolled environment is crucial to optimize the process. The control parameters for oxidation process are, availability of oxygen, temperature, humidity and time. Humidified air is supplied into the fermenting systems – Floor, Gumla or CFM – to ensure an oxygen rich humid environment. Elevated humidity restricts depletion of moisture from the CTC processed leaf. A hygrometric difference of around 1-2 0C is recommended for the above. This in turn also helps in reducing the room temperature closer to the recommended level of 27-30 0C. In most commercial tea factories, spot humidifiers and overhead duct humidification system are used. But they are being rapidly replaced by more efficient misting or fogging systems which enable ambient humidification with micro fine droplets. This paper presents the results of the trials conducted with a High Pressure Fogging System which was installed at the Model Tea Factory, TTRI, Jorhat. The effect of this technology was extensively assessed/reviewed in fermented dhool, as well as on made tea over a period of two years. Results show that it was possible to achieve a humidity of 91.8% to 95.9% inside the fermenting room while the prevailing ambient humidity levels recorded varied from 71.9% to 74.40%. The appearance of the treated samples on fermentation bed was very bright and the made teas were preferred by the tasters. However, the above observations were more pronounced on days of low ambient humidity,in which case the tasters’ scores on made tea were significantly higher with respect to brightness, briskness, strength and quality, compared to the control samples.

Keywords: Misting system, Fogging system, Cooling systems, Humidifiers, Polyphenols, Theaflavins, Thearubigins.