Blackberry and raspberry plants are prospering and are gifting several handfuls of delicious fruit everyday. There are plenty of leaves, which actually make for a refreshing herbal tea, if only treated the right way.
While they could be just quickly dried and used as such, blackberry and raspberry leaves are much more aromatic after a short “fermentation”, which is in fact rather an oxidation, similar to the way black tea is processed.
One starts by picking well-developed but young leaves (not leathery). You may want to wear gloves, even some raspberry varieties can be quite spiky on the leaf base. They leaves then should be left to wilt for a day.
Once they have lost most of the water so the leaf lamina won’t break easily anymore they should be squeezed properly, while being exposed to fresh air (=oxygen). One can use a dough roller on a wooden board, for example. During this treatment the leaves will already change colour to a darker tone, quite like “real” tea from Camellia sinensis does. Now that mass can be rolled into a “sausage” and tightly wrapped into a kitchen cloth, if it feels rather dry sprinkle a small amount of water over before. This leaf sausage may then be stored in a warm place, 30 degrees Celsius / 86 degrees Fahrenheit seem to be optimal. Occasionally give the sausage another good squeezing (no need to open it). After 3 days the leaves should have a dark reddish-brown colour and an aromatic / fruity smell. Spread them to dry properly at low temperature, i.e. on an oven tray (try to stay below 50 degrees Celsius / 120 degrees Fahrenheit during the drying process in order to preserve the aroma). Once they are dry enough (at least on the edge of breakage when touched) they can be stored in a mason jar.
To brew a tea, use a teaspoon of your fermented leaves per cup, pour hot water over which just stopped boiling, and allow it to infuse for 5-10min.
Because it was so simple, here’s an alternative way to approach the leaf oxidation: Take the freshly harvested, unwilted leaves, roll them into a sausage, slice coins with a knife or use large scissors, so you get stripes just a few millimeters wide. Throw them into a cotton back, hang it into the sun and occasionally shake the bag. Once the leaves have wilted sufficiently, stuff the whole bag or just its contents into a freezer bag, seal that, store in a warm place (some people had great results on the dashboard of their car, but on sunny summer days it may not only get very hot in there, it may also raise questions what “substances” you are transporting here…) Every day at least once that bag should be opened for ventilation, after a few days the moisture content will have greatly reduced and the leaves crinkled like an Oolong tea.
Another good fermentation device is a baby bottle warmer. Since the little creature is off the milk, that machine stands there for nothing, and begs for new use. The one I inherited has digital temperature control and can be set to 30 degrees Celsius / 86 degrees Fahrenheit, which it will keep quite exactly for however long. A small mason jar in the bottle chamber retains the moisture. Note that at temperatures below 50 degrees Celsius / 120 degrees Fahrenheit mould will appear sooner or later, so again, limit fermentation time to 3 days to be on the safe side.
Strawberry leaves can be processed in a similar way, and many others. Some may have medicinal effects (which means potentially also side effects), so esp. when mixing different varieties or if larger amounts are consumed regularly it’s advised to consult knowledgeable books or people on the matter.
The result: Homemade, organic blackberry leaf tea