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?
