I have a recipe that calls for a large pot of strong mint tea. I don't have time to make the recipe these days, but I'd like to make the tea before the spearmint in the garden dies off so I can finish this later when I have time. My plan was to harvest the remaining mint (I was going to include the stems as well since by now I've already used many leaves - but would stems affect the flavour in a negative way?), brew a pot, then put it in a container and freeze it, and then thaw when necessary. Would freezing affect the flavour?
Some of the volatile flavors will be diminished, but I've managed to make fairly good drinks with the help of mint that I kept frozen. In my experience, freezer burn starts to become visible after two or three months, and starts to harm flavor probably around 4-6 months.
I'm not sure preparing the drink will work really well, but if you just defrost the drink in the refrigerator, it probably won't be terrible. Active thawing with heat will probably cause some harm. Many infusions and teas become a bit cloudy and lose color after bottling or freezing, which is why most bottled teas use an enzyme (not usually a listed ingredient) designed to mitigate that.