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From a few Chinese friends, I have been told that keeping tea in the freezer will keep it fresh. This makes sense, and I have kept some tea in my freezer in the past. However, I noticed that on this site, keeping tea in a refrigerator is mentioned instead of a freezer. I haven’t been able to find any really reliable information that addresses this subject. Any thoughts on this matter? Is it safe to keep tea in a freezer? And also, how does keeping tea in a freezer compare with keeping it in a refrigerator?
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That’s correct. Although keeping tea in the freezer does keep the color for a much longer time, the tea would degenerate much more rapidly upon return to room temperature. This is a topic that concerns freezing technology and we have not found any scientific documentation yet concerning similar topics. All we have written is from what we have observed and experienced. I hope with the hopeful increase of the general consumption of finer green tea, corresponding research in the issue can be addressed and we can have fresh green tea supply all over the world all year round. I think the this would involve only a simple application with existing technologies, but the costs of it is barring small producers from trying it. The catch is, almost all finer teas are produced by smaller producers.
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Very interesting. I would guess that this has to do with the natural level of moisture in the air of the container, which would turn to a bit of frost while frozen, but condense into water when taken out of the freezer. That would lead to moisture being absorbed by the tea leaves, causing them to spoil. That is my best guess. I’ve had some tea in my freezer for almost a year, and the tea leaves always looks just as they did when I got them. I’ve been careful because I was not sure how much changes in temperature would affect the tea. Each time, I only have the container out for a few seconds.
For producers, one approach that may avoid the situation altogether, might be to vacuum pack the tea in order to suck out all the air (and therefore moisture) that would affect the tea during storage. Then the vacuum packed bag could go into an opaque container. Something like this approach might be pretty thorough in protecting the tea against issues of temperature/moisture and issues of light. I wonder if small producers could stockpile kilograms of tea like this if they needed to, and have very fresh leaves at any time? Maybe if the process were good enough, they would even start freezing the tea as a matter of course, following the production process?
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It is great to know that there is one more person paying great care in maintaining the quality of your tea collection, coz there aren’t many.
The vacuum + quick freeze method had been practiced by the tieguanyin makers for quite many years, but the shelf life isn’t that much longer than that of those green teas that are just stored chilled. A packer once propose to me the use of nitrogen-filled pack and chill. The Japanese use silica gel and chill… there are different practices and all with something in there.You are right in pointing out that moisture is an issue. I’ll certainly write more about that, but I am not sure if that is the only thing that makes a green tea fade. Most green tea are dried to a standard of 5~7%, but they still fade within a vacuum pack. I think it simply isn’t a great topic enough for scientists. At least not until some of them find out how good fresh green teas are. -
I think one could explain the degradation of freezed green tea with that of freezed meat once at room temperature, although they are not the same, obviously. Simply, freezing in one’s home freezer produces low density water cristals in meat cells, thus breaking the cell membrane and releasing all the content as a watery solution (have you ever noted some water forming under your unfreezing meat? Most vitamins are right there!). This does not appear on deep-freezing (done by food industries), because this type of freezing is done by decreasing dramatically and immediately the temperature, with no possibility of large cristals to form. In this way, meat retains more than about 95% of all its substances (included vitamins).The basis of this is that water molecules acquire different conformation in the space in becoming ice, due to temperature and time of freezing (just to visualize, think about the difference you find between snow cristals and grains of hail).I know, dried tea has very little water inside, compared to meat, but I think the behaviour is the same if you freeze your tea at home: once at room temperature, moist oxidation quickly wastes it.
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I think water definitely has a part in this, but I am suspecting the home freezer type of gradual temperature change may cause actual chemical changes in some of the less stable materials in the tealeaves. I am still lacking time to look into this aspect so I can not point a finger at anything.
Fine tea holds so many different substances in it to make it fine and so many of them are so delicate. They give us the subtlety in the experience and yet they can be gone so easily. So much the same in that many other things in life.
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