The Sap is Rising
I’ve a confession: although my long-standing interest in wild food cookery does add incredibly wild and nutritious versatility to my daily menu with respect to rich soups, unique salad combinations and intriguing side vegetables – all very health promoting and worthy; truth be told, I’m actually somewhat of a sugar addict. Yet, for the most part, sweet wild foods are associated with the abundant fruitfulness of summer and autumn – apples, pears, cherries, blackberries, bilberries, mulberries etc, and as delicious as such fruits are in their unprocessed state or as fruit leathers, their sweetness is invariably counterbalanced by varying degrees of acidity. Hardcore, unadulterated and non-toxic sweetness is actually quite hard to come by in the natural world, at least where I live. Yet, from as early as the final week of February (Southern England) until as late as the end of April (Scotland), and with a similar early to later coming of the spring across the different states of the US, that hardcore sweetness lies quite literally in untapped abundance, residing in diluted form within the trunks of some of our commonest trees: Birch (Betula species), Lime (Tilia species), Sycamore (Acer species), Walnut and various others. All, in theory, can be successfully tapped for their sap, the first two providing the best results in my experience. Birch, especially, is fail safe!. Indeed, on the basis of research and reports of success in this regard, I’ve tried to tap both walnut and sycamore for sap from February to April for the past 7 years, but without success. This year I intend to try our only UK native maple for the first time: The Field Maple (Acer campestre). For the purpose of this article then, ‘sap’ refers to birch sap only. But why bother doing this? This is a question I’m frequently asked, quite often by people who have tried and have been disappointed that what drips from the tree tastes pretty much like water, not the sweet ambrosial nectar they had expected. Well, it’s a reasonable question I suppose. There are many answers………..
|23rd March 2012. 6.30am, 0 °C brrrrrrr!|
In the Ukraine and parts of Russia the sap is collected and sold as a type of mineral water, so they clearly value it. A fantastic, easy to make and reliable white wine can be made with a very distinct and pleasant taste, as well as beer, vinegar (see recipe at the end) and a rich caramel and molasses-like syrup. But, above all else, as with all foraging, it provides an excuse and opportunity to arrange your life according to the cycles of nature rather than the oppressive dictates of work routines and the terrible tick-tock tyranny of clock time or even traditional calendars. Each year I try to refine my understanding of when the sap flow begins and when it’s in full swing. This year it begun a day before the spring equinox, 5 days after reports that frogspawn was appearing in local ponds, and two days before the wood ants began to awake from winter slumber as they amassed to form new colonies. This is the realm of magic, awareness, and attunement, connecting with life, poetry and mystery and clocks serve no purpose!
The sap then, which is actually about 95% + water, minerals and a little sugar, can be evapourated off to make a sublimely delicious if somewhat energy intensive syrup – it is the absolutely perfect accompaniment to elderflower fritters. In fact, the only near equivalent you can buy in this country is maple syrup. That is commercially viable because the ratio of sap required for a litre of syrup is 30:1, whereas for birch it is between 80 and 120:1 (I usually find that a 95:1 ratio is perfect). But don’t let that put you off. Once you’ve tasted birch sap syrup, the effort required to make it will seem more than worthwhile. For those who are unconvinced there are several other excellent uses for the sap once collected as I shall explain below, as well as various birch-related bushcraft skills to practice while the sap is simmering. First, though, how exactly is it obtained? There are several possible collection methods; here are just a couple. Between the end of Feb and mid-April when temperatures are usually between 0 and 15 °C – but especially in the second half of March, take a metre length of 0.5-1cm diametre plastic tubing, a 2 or 4 litre plastic bottle (keep spare tops to put on the bottles when returning to pick up the sap – or just return with a large container), a drill with drill bit the same diametre as the plastic tubing, a piece of tissue or cotton wool, a lump of plasticine (modeling clay) or natural clay, a wooden bung and a hammer. Select a suitably sized, well-established, and healthy looking tree (unhealthy trees don’t take so kindly to having more pressure pot on them by the likes of me or you drilling a hole in them!) – at least 8-10 inches across. Also, especially if in a woodland with lots of birch competing for space and light, go for the trees with the largest crown of branches. These will have the best sap flow. Mark a spot 2-3 feet up from the tree’s base. (In fact, you can tape a collecting vessel to the main trunk 15 foot up the tree if you don’t want it to be disturbed – useful if the trees are in an urban environment where your collection set-up might be tampered with lower down).
With the drill bit angled about 30 ˚ up from the horizontal (although straight in is fine too), drill a clean hole about 3-4 cms deep into the tree. Blow out bits of debris (close your eyes!). Liquid should drip from the hole within 10-20 seconds at the rate of 4 or more drops per second at the peak of sap flow. If not, hammer in a wooden bung or piece of clay and try another tree. Push one end of the plastic tubing 1-2 cms into the hole so that it is held firmly in place. Place the other end into the collecting bottle, far enough in so that it can’t slip out. Gently pack tissue or cotton wool around the tube at the neck end of the bottle, allowing the air to escape as the bottle fills with sap and to prevent insects from getting in (you can just cut or melt holes into the top of plastic lids – but make sure it isn’t a completely tight fit as you need to allow air to escape from the bottle as it fills up). Scoop out a handful or two of soil at the base of the tree and place the bottle in the shallow hole created to prevent it falling over. As a precaution, to prevent any leakage, you can roll out and press a small piece of plasticine or clay around the tube to make a perfect seal with the tree trunk. Leave for 12-48 hours, after which time the bottle will most likely be brimming with sap. Alternatively, you can use a small length of tubing or a small elder stick after clearing out the soft central pith, and allow the sap to drip freely into a collecting vessel such as a demijohn – preferably using a muslin covered funnel to direct the liquid and prevent insects falling in (or use a maple tap). In woods where there are wood ants, the ants will amass around any exposed sap. Finally, plug up the hole to prevent infection of the tree, particularly from fungal spores. Hammer in a hard wood bung, firm piece of cork cut to size, some clay or, as a temporary measure, a piece of plasticine. Whatever I use, I always line it with fresh cherry resin. Resin production is a tree’s healing response to mechanical damage so is worth using. It also makes for a really good seal. At this point it is certainly worth drawing your attention to the ‘to plug or not to plug’ debate going on right now, with some evidence suggesting that using a bung or plug may in itself disrupt the trees ability to heal itself or trap spores and microbes, leading to infection. Follow this link for an article exploring these issues that, helpfully, also documents (apparent) ‘best practice’ Some impacts to paper birch trees tapped for sap harvesting in Alaska
If in doubt, ask the tree.
If in doubt about asking the tree
Use your intuition.
If in doubt about using your intuition
Read (and apply the techniques) described in
Craig Holdrege’s Thinking Like a Plant
and Nathaniel Hughes and Fiona Owen’s sublime
I take no more than about 4 litres per tree (when drilling), and only tap the same tree on alternate years. Nevertheless, some people will tap continuously from one tree throughout its entire period of sap flow, but only return to that tree every 4-5 years; others take 2 litres and return every year to the same trees.
|A great drill, but often hard to see when I put it down among the forest floor leaves!|
Perhaps though, best practice is to abandon hole drilling altogether. A single branch cut towards the end where the diameter is approximately 1 cm across, can yield up to 1 1/2 litres of sap in 24 hrs if a piece of tubing is tightly fitted over the end and run down into a bottle. 4 tubes running from different branches on the same tree can collectively yield more than a single drill hole in the same time. In addition, these can be cleaned with boiling water and birch tar sealed. Even without the clean and seal, it seems possible, if not probable, that this more gentle and less invasive method is likely to be less harmful to the tree than hole drilling.
Collect lots of birch bark from well rotted fallen trunks. Stuff tightly in a large round (see picture) in a cake/biscuit tin that you’ve made a hole in (use a nail and hammer – hammering from the inside so direction of hole directed outwards). Fit the lid on tightly. Dig a hole to snuggley fit a tin can in. Place cake tin on top. Make a fire on top of this and burn for 2 hours. This will dry distill the
tar/oil/pitch out of the bark. Remove the tin from the hole and place on hot embers to boil and reduce the tar by half the volume. Note: the jar of oil below is floating on water that was also in the can. That’s because the bark was damp. If fully dried first there will be no water.
I made a clean fresh cut 6 inches back from the original cut, sterilized with freshly boiled water and brushed on the thick tar.
The above attempts to seal exposed branches with tar were my attempt to honour the tree by going through a process requiring dedication and best intentions. In practice, my optimism proved somewhat naive. Sap flow is powerful and is very hard to stop! In the end I had to combine traditional and modern materials. What worked to stop sap flow 8 out of 10 times was moulding a piece of tar (consistency of cold chewing gum) into a piece of modelling clay, and pressing tightly on the branch (tar on its own only worked to stop the flow 2 out of 10 times). More experimentation required……………..
Finely, before moving on to working with the collected sap, here are a few other interesting tapping techniques from around the web. Personally, I prefer the branch collection method now, but at least the following demonstrate an impressive (but not difficult) degree of skill and a willingness to work with natural materials:
Ray Mears (collecting sap for his mint ice cubes to go in his single malt)! Similar technique to Alexanders.
Lonnie of Far North Bushcraft’s green willow tap, creating a central hollow using just his knife.
What to do with freshly collected sap?
Unless you intend to use the sap for cooking or drinking immediately, refrigerate and use within 2-3 days. If you decide to tap one tree throughout its sap rise, empty out the collecting bottle within 48 hours (at the latest – after 24 hrs if the temp is above 10 °C) of tapping or when your collecting bottle is full – whichever occurs first. If you leave the container over 2 days before collecting, the natural yeasts present may already have stated to ferment the sap, using up what little sugar there is, giving rise to off flavours – these become intensified when reduced down during syrup production and are to be avoided. Note: if you want to transport large quantities of sap, I recommend scrounging several of those large 18 L capacity mineral water bottles seen in offices. These are also excellent for wine making.
Boil the sap until it is thick and dark, barely simmering at the final stages to prevent the disaster of burning. Indeed, at the latter stages the pan should be just on hot embers – no direct flame). Indeed, once the volume of sap is reduced from 95 to about 5 litres, I usually transfer the syrup to a new pan and place indoors on the hob at the lowest flame setting – not even simmering. Also, unless you want to deep steam clean your kitchen or make the wallpaper peel off, this is definitely a job to do most of outside. Alternatively, ask a friendly baker if you can place a large metal tray of sap on top of his bread oven to slowly evaporate. Taste repeatedly as you concentrate the sap to reach your required degree of sweetness. It is inevitable that the sugars will partially caramelize, that however is just an integral part of the flavour (in the absence of expensive industrial machinery to produce the syrup using reverse osmosis). If concerned about burning there is no need to reduce 95 L sap to 1 L of syrup. The ratio of 50:1 also makes for a gorgeous but lighter and runnier golden brown syrup.
|Evapourating off the water and removing scum.|
It can take 4-5 hours or more to make a litre of syrup. That time, however, presents a real opportunity. You can collect birch bark for fire lighting, collect birch polypores for making razor strops, paper, shoes or, best of all, you can make birch tar (as described above). Talented bushcrafter Jonathan Ridgeon’s excellent no nonsense online tutorial is also worth reading for more detail:
Or how about collecting some bark and making a simple birch bark and spruce root basket: Perfect for collecting the stunningly impressive Scarlet Elfcup fungi that are still in season now.
Nevertheless, if syrup making still seems too much trouble use the sap to make a lovely refreshing wine instead. It’s easy and is definitely not a second best alternative. Start by making a high alcohol tolerant wine yeast starter culture. For this, simply follow the instructions on a packet of wine yeast – usually this involves adding a teaspoon of yeast and sugar to about 3 fl oz of boiled and cooled water that is then shaking in a clean sterilized bottle. The top is loosely fitted on and the bottle left in a warm place for about four hours or until the yeast becomes active – you’ll notice bubbles rising and a little froth forming on top. Next, sterilize 2 demijohns, 2 rubber bungs, 2 air-locks and 1 plastic funnel – the products used for cleaning babies’ bottles are fine for this purpose. Put 8 pints of sap and 1kg of sugar into a large pan and bring to the boil stirring in all the sugar. Add the juice of 1 lemon and 1 teaspoon of yeast nutrient. Empty and rinse the sterilized demijohns with boiled (but cooled slightly) water. Divide the sap equally between the 2 demijohns, pouring in using the sterilized plastic funnel. Allow to become luke warm before adding the yeast starter culture and fit bungs and air-locks. Leave in an airing cupboard for 5 days before transferring all the sap into just one of the demijohns. Ferment until no bubbles appear in the air-lock (2-3 months).
|Birch sap wine in demijohn and glass. Spoons showing commercially produced maple syrup (left) and birch syrup (right).|
If you’re feeling both naughty and adventurous you could also get hold of an old-style basic pressure cooker, a siphoning tube, a bucket of cold water and a demijohn to distill your birch sap wine to make birch sap moonshine. That could then be used for Russian-style preservation of gorgeous chanterelle fungi, gathered from around the same birch trees you have tapped. Of course, it would be illegal so I must advise against it. I just said “you could”, not “you should”.
|Chanterelles preserved in alcohol|
Finally, you’ve decided you’d like to try out some of the suggestions above but, it’s 1st April, you’ve drilled a hole and are standing there feeling like a true April fool because not a drop of sap is flowing out. Don’t worry, the sap rise is over. The leaf buds are swollen and bursting into life. Excellent! The young tender leaves are good for tea (would be a good experiment to ferment them in the way true tea leaves are) and excellent as a mild bulk salad leaf. But don’t miss this opportunity either as the leaves only stay tender for about 2 weeks!
|2 litre capacity vinegar aging barrel|
Ingredients (makes approx1.5 L) 190 L fresh birch sap 1 sachet high alcohol tolerant wine yeast Method Boil the birch sap down to 4 L. Place half of this i.e. 2 L into a sauce pan and carefully (on lowish heat) very gently simmer, reducing down to 1 litre. Pour half of this into a wooden barrel and leave for 4 months; pour the other half into a sterilized glass bottle and seal. Place the other 2 L in a sterilized 1 gallon demijohn. When warm or cooled sprinkle on the yeast (or use wild yeast cultures if desired). Fit an air lock, place in a warm cupboard, and ferment until no bubbles appear in the air lock (approx 4 months). Uncover and expose to the air and fruit flies for a few days. Then cover with muslin and allow to turn to vinegar. This takes about 2 months. Pour vinegar into wooden barrel to add to the syrup already in there. Age for 25 years, transferring the vinegar to a smaller barrel of a different and suitable wood variety every 5 years. Finally, ballance the sweetness and acidity by adding some of the bottled and pasturised syrup.. Confession (you probably realize this already!): I’ve not done this, at least not completely. I have followed this recipe and aged the vinegar for 3 years. I’ve also experimented by just letting pure sap ferment (I say ‘experiment’, but actually it was a mistake as I’d not sterilized the bottles well enough. But, of course, there are no mistakes! It made me realize that it was worth exploring as vinegar and, in particular, a balsamic style vinegar). The flavour of that spontaneously fermented sap is different from wine that has been turned to vinegar, hence the different stages in the recipe. This recipe is the nearest I’ve managed to get to something approximating balsamic vinegar using only wild ingredients. It tastes good, but would be fun to age some for the length that Aceto Balsamico Tradizionale is aged………… One final thought………… Do keep your eyes peeled for Birch Polypore fungi, also known as Razor Strop Fungi, as you are bound to come across them when you’re out looking for suitable birch trees to tap. These can be found on dead standing trees or on toppled trunks and fallen branches. Of course you can make razor or knife strops with these, but far more fun in my opinion is to use them to make paper. Be careful not to have the fungi knocking about in your bag with your drill. It will get contaminated with spores and you may end up infecting previously healthy trees!
|A good crop of Piptoporus betulinus|
|Underside showing the pores|
|Dried, scaped and vacuum sealed Birch Polypore|
Many other common rubbery textured fungi can be used to make paper too. Here’s some basic information on how to do it: http://www.theforagedbookproject.co.uk/wp-content/uploads/2012/09/Basic-Guide-to-mushroom-paper.pdf Have fun out there!