Posted 23 March 2021 by Matt / In Mackmyra
Bottle Name: Bjorksav
I’ll admit to being a little surprised seeing comments suggesting of the weirdness of combining birch sap with single malt whisky. Björksav is far from the distiller’s first foray into this traditionally harvested tree juice – nor is it in my opinion even in the running in the odd alcohol stakes (more on that in a moment). Indeed, beverages crafted from a variety of tree saps – birch, maple and also bamboo - are nothing new. Tapping for sapping has been commonplace for generations upon generations. Often stemming from traditional folk medicines, in some countries the use of sap has grown into cottage industries. And in the case of birch – alcohol production is similarly nothing new – the sap can be fermented in a similar manner to pulque or palm wine. When it comes to combining things with alcohol there are far stranger things…
Top of my personal list of outlandish amalgamations is surely Fishky – a single cask Bruichladdich that was finished in a sherry cask. But not just any sherry cask. This sherry cask previously held everyone’s favourite oily fish – herring. Ex-herring casks have not, outside of this infamous absurdity, been seen since. And there are even more extreme examples of truly gut-churning alcoholic drinks out there – baby mouse wine (which I won’t even do a service of by highlighting the production methods employed here) – Three Penis Liquor (seal, deer and Cantonese dog for those who were wondered “which three?”) and pizza beer – which is not just a pizza served with a beer. You name it, some idiot has doubtless tried to make it.
Birch sap – a beverage with a long history of both consumption and transformation into alcohol therefore seems like a relatively safe bet in the grand scheme of things.
Tree water is about as natural as it comes. It’s unadulterated and undiluted. And whilst most people expect sap to be brown, sticky and resinous (viewings of Jurassic Park will no doubt reinforce this perception) – the sap from many trees is as clear as water. And as immediately drinkable. Birch sap is arguably the most common sap to be tapped – the process is simple bushcraft, and involves drilling a hole through the bark into the outer layers of the heartwood and then using a straw (or hollowed out length of elder if you’re being a fancy pants) to guide the sap into a vessel for collection. The liquid is just as refreshing as coconut water; however, it only contains 25% of the volume of sugars.
As such, converting birch sap into alcohol – requires some skill and knowledge. The main sugar source in the sap is fructose which is more temperature sensitive than other sugars and similarly, its concentration is very low – as little as 10g/L – which by itself would only ever produce 0.5% alcohol – it therefore needs to be boiled first to increase the brix of the juice. Oh, and it doesn’t last very long either – around four days when refrigerated.
As a liquid, birch sap is naturally sweet and nutritionally rich. It is also an entirely appropriate component of Mackmyra’s first seasonal release (Säsongswhisky) of 2021, as birch trees are tapped for their sap in Spring.
In winter, deciduous trees enter a dormancy phase. Their leaves drop and their natural sugars move down into their roots. But, with the onset of Spring and warmer temperatures, the sap begins to flow up the tree – moving from the roots to the twigs, where its sugars provide the natural energy required by the tree to grow new shoots and leaves. The release of Björksav is timed perfectly for the onset of Spring – and this rising of the sap which often takes place around the month of March.
The release itself is composed of three types of casks – standard sized ex-bourbon barrels, oloroso seasoned American oak (from roughly quarter cask through to American standard barrel in size) and birch sap seasoned Swedish and American oak casks varying from 100-200 litres. The product sheet, which I wish more distilleries would produce for their releases, provides a breakdown of the cask percentages for those interested in even more granularity. And shows that Björksav is far from a simplistic ensemble of casks:
- Whisky aged in ex-Bourbon casks - 30%
- Whisky aged in oloroso casks - 24%
- Whisky finished in birch sap wine seasoned casks - 20%
- Whisky aged in other types of seasoned casks - 18% (interestingly unspecified here)
- Whisky aged in casks of Swedish oak - 8%
The release has been produced in collaboration with Grythyttan winery who produce a wide array of products – including berry dessert wines which have been used in other Mackmyra releases. It is currently available directly from the Mackmyra webshop and will cost you £62.
Nose: Immediately fresh and crisp with Mackmyra-eque crunchy Granny Smith apples joined by a scattering of lemon peels and floralness from elderflower tea. The intensity of expression increases with time spent in the glass – nutmeg spiced milk, creamy vanilla-imbued chocolate and honey spread over sweet brioche rolls. Running throughout is a ‘green’ leafy quality – part earthy tobacco, part fresh, verdant undergrowth. The addition of water amplifies these vegetal aspects further with herbal green teas, freshly cut grasses and additional spice notes of cinnamon.
Taste: Thickly composed with a pleasant mouth cling. And still with a profile focussed on freshness and precision. Orchard fruits with lemon gel sit alongside zingy spun sugar, whilst thicker golden syrup is joined by resinous oak that possesses a forest-led character. The back palate favours the distillate and ex-bourbon casks with gingersnap biscuits and underlying maltiness played off against gentle char and powdered nutmeg. Dilution again amps up the perception of vegetation with minty wintergreen oils alongside anise and green pepper.
Finish: Medium to long. Sweet, crunchy apple is offset by roasted cereals, toasted oak and aromatic wood spice.
Mackmyra’s Björksav is a convincing and balanced release – and to my palate, the best I’ve seen from the distillery for a number of years. The selection of casks is highly sympathetic to Mackmyra’s distillate style, whilst also providing an excellent foundation to showcase the inherent tastiness of birch sap. Far from being a novelty ‘addition’ – the sap’s influence is both supportive to the overall composition of the whisky as well as being palpable throughout – particularly with a drop of dilution. This sweet and naturally spiced tree water only goes to add further dimensions of empathetic flavours to what is a crisp, fresh and honed single malt. There are far stranger things than birch sap – especially when you’ve got Spring in a glass.
Review sample provided by Mackmyra
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