What is Withering?

by Tony Gebely 446 views9


The moment a tea leaf is plucked from the tea plant, it begins to wilt naturally, a process we call withering. But once the tea leaves reach the processing facility, this process is controlled by the tea producer. The purpose of a controlled wither is to prepare the leaves for further processing by reducing their moisture content and to allow for the development of aroma and flavor compounds in the leaves. Controlling the withering process means closely monitoring humidity, temperature and air-flow over time. A controlled wither can occur outside with tea leaves laid out gently on bamboo mats or tarps, or indoors in troughs with forced air. The air may be heated to speed up the process if necessary. Great care is also given to the density of the withering leaves to ensure that they wither evenly. The withering process is complete once the tea leaves have achieved a desired percentage of water-loss. This is determined by the final weight of the tea leaves after withering or by the flaccidity and changes in the aroma of the leaves.

During withering, the moisture content in the leaf is reduced by about one-third to one-half, making the leaf flaccid and pliable. This prepares the leaf for further processing, usually shaping and rolling. On the chemical side of things during withering, chlorophyll in the leaf begins to degrade, caffeine levels slowly rise,, flavor and aroma volatiles develop in the leaves and grassy aromas dissipate. Since the leaves are cut off from their supply of energy, they also begin to break down their stored carbohydrates for use as energy. The loss of moisture also causes the cell walls to break down, initiating polyphenol oxidase and peroxidase activity – the reaction known as oxidation. The longer the wither, the more aroma and flavor compounds develop in the leaves. This is because during the withering process, many of the chemical compounds in the leaves degrade into volatile compounds. In fact, many tea makers use their sense of smell to tell when the withering process is complete. If the leaves are withered too long, polyphenol and peroxidase activity will cease due to dehydration. Once withering is deemed complete, processing continues.

If you found this interesting, be sure to check out my posts some other individual processing steps: oxidationkill green and drying. And finally, my tea processing chart.

Photo source: http://www.flickr.com/photos/litrate/

Comments (9)

  1. A really good article. However, the technology used to achieve controlled withering, by local tea producers, is still not up to date. therefore, most tea manufacturers don’t get the most out their tea leaves.
    However, keep up the good work! Conratz on your book!

  2. I don’t like an idea of deliberately making leaves wither for two reasons

    1. I feel bad for the leaves. Well sure they will die when you HAVE to eat them, but making them deliberately suffer is just cruel.

    2. If we talk about withered salad, most ppl would agree it would taste disgusting. So, even if I know that tea tastes good the mere “knowledge” that such taste comes from withering makes me dislike the taste (and I used to really like tea up until 5 minutes ago when I ran into this article!)

    I realize that anything cooked is also withered, but the idea of making un-cooked leaves wither (whether or not they are cooked later) is totally disgusting. I would never want to cook a soup out of withered vegetables!

  3. wonder full facts about tea i have got,i would like to learn more about tea manufacture processing, thanks 4 the facts

  4. thnks 4 ur information…..

Leave a Reply

Your email address will not be published.

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>