Humidity control in tea production is a critical process parameter determining enzyme activity, oxidation rate, and the aroma profile of the final product. The fermentation stage forming the basis of black tea production is actually an enzymatic oxidation process; the polyphenol oxidase enzyme in the leaf converts catechins to theaflavin and thearubigin compounds, creating the characteristic color, taste, and aroma of tea. The speed and depth of these enzymatic reactions are directly controlled by the temperature and humidity conditions of the fermentation room.
During the withering process, the first stage of tea processing, fresh leaf moisture content is reduced from 75-80% to the 55-65% range. Maintaining ambient relative humidity at 60-70% during this controlled drying ensures gradual reduction of leaf turgor pressure. Excessively rapid drying damages leaf cell membranes, prematurely triggering undesirable enzymatic reactions; excessively slow drying extends the fermentation process and reduces quality. When the withering environment humidity profile is precisely controlled using industrial humidifiers, leaf flexibility is preserved and optimum conditions are provided for the subsequent rolling operation.
Maintaining relative humidity at 90-95% in fermentation rooms is mandatory for enzymatic oxidation to progress in a controlled manner. During this stage, temperature is controlled at 22-26°C and enzyme activity on the leaf surface is maximized. When humidity is insufficient, the leaf surface dries, reducing enzyme-substrate contact; consequently, tea remains light in color, shallow in aroma, and insufficient in flavor. Fermentation duration varies between 45 minutes and 3 hours depending on tea type, and the stability of humidity conditions throughout this period guarantees product consistency.
Since fermentation is not desired in green tea production, leaves are rapidly heat-treated post-harvest to inactivate polyphenol oxidase enzyme. Humidity control during this process is important for preserving leaf tissue and ensuring homogeneous heat treatment. In oolong tea production, partial fermentation is applied; ambient humidity is adjusted between 70-90% according to the desired degree of fermentation to achieve the intended oxidation level. Each tea type's unique humidity profile demands high precision and flexibility from the production facility's humidification system.
After drying, tea leaf moisture content is reduced to the 3-5% range, completely stopping enzyme activity and giving the product storage stability. Maintaining relative humidity at 50-60% in packaging and storage environments prevents hygroscopic dry tea from absorbing moisture. Tea that absorbs moisture becomes stale, loses aroma, and mold risk develops. The warehouse humidification system must have adaptive control capacity responsive to seasonal outdoor air conditions.
As NKT Humidity Control Technologies, we provide expert engineering support for tea production facility humidity management needs with our industrial humidifier solutions. For humidification system design suitable for your facility conditions, please contact us using the form below.
