In our ongoing quest to figure out what to do with acres and acres and acres (and acres) of blackberries, I came across a mention of making blackberry leaf “tea” with the leaves. We’ve used our raspberry leaves for tea for a few years now and love it, so I decided to give it a try. After doing a bit more research, however, it seems that the blackberry leaves are much improved in flavor if they are “fermented” first. Which basically means you treat them like real tea leaves and bruise them, then allow them to oxidize for a while to develop a darker color and richer flavor. I made a small batch the last time we were up at the property, and everyone loved it, so I decided to make more. There are several sites with instructions for doing this online, but I haven’t seen many how-to articles with pictures of the process, so as I was making this last batch I took photos from start to finish.
Step 1: Pick the blackberry leaves. These are from the notoriously invasive Himalayan Blackberry, which means they are abundant, large and full of nasty hooked thorns. Wear gloves and use snips. And expect to get snagged now and then anyway.
Step 2: Let the fresh leaves dry and wilt slightly. You don’t want them too wet, or they will mold and rot instead of oxidize. I don’t have a picture for this step because, to be honest, the pile of leaves looks pretty much like they do above, except a bit drier and slightly more limp.
Step 3: Bruise the leaves. I did this by laying them out in small batches and rolling a small wooden rolling pin over them until they were slightly crushed all over. This releases the leaf juices and exposes them to the air. Soon after you have done this, you should smell an almost perfume-y smell, with a hint of fresh rose scent. (I don’t have a picture of this step, either, but will probably edit this post to add one when I process the next batch.)
Step 4: Put the leaves back into a perforated bag or wrap in a damp cloth and let them sit for two or three days in a warm(ish) spot out of the sun. I used a plastic bag that was not tied shut, and checked the leaves several times a day, turning and mixing them to expose them to the air more and to keep them from sticking together and molding. I have read of others using a thin cotton cloth, pillow case or bag for the task. Just make sure they don’t dry out too quickly, or the oxidation will stop before it has reached the right level of browning. Here is an example what the leaves should look like once they have been fermented.
And here is a close-up of one of the fermented leaves. You can see where the leaf cells have been broken and the leaf juices exposed to the air.
Here is a picture with fresh leaves next to the fermented so you can better see the contrast.
Step 5: Put the fermented leaves into a dehydrator, and, using the middle settings, dry them until they are quite crisp. You can crush the leaves later and remove prickly stems, or just leave them. I tend to like to remove the thorny stem midribs and petioles, but sometimes when I don’t have time I just leave them.
That’s all there is to it! Fermented blackberry leaf tea is less “herbal” tasting and has a pleasantly mild fruity flavor that you just don’t get with the green leaves before oxidation. It is good alone and also with other herbs, such as mint.