by Ben Reade.
Part 1 by Ben Reade
Our recipe for elder
vinegar. Begun from a elderflower wine and undergoing a second fermentation on
the berries, this vinegar has good aging potential. The fermentation makes it safe
from any potential cyanide, and the acidity brings out the floral, fruity notes
over the muddy, watery ones. It is delicious.
So, sometime in the spring
of 2010 while I was living in Italy I got into making elderflower syrups – it’s
something I’ve grown up around in Scotland, a favourite taste of summertime.
During my childhood, around 50% of the bottles would start to ferment (some
would explode) and when a good recipe was stumbled on by chance (my mum would
never weigh anything), a delicious sparkling wine would magically appear. Now,
elderflower champagne, as it’s often know, is as old as the hills. It’s
delicious, always gets consumed faster than expected, and everyone always
wishes they had made more.
A good recipe for a
traditional elderflower syrup is:
80 heads of elder flowers, removed from green stems (harvested
after some days of sunshine)
g citric acid
and juice of 6 (*ahem*, nordic) lemons
sugar and water, pour over the rest, cover and leave for 24 h. Strain.
If you want to bottle it
to keep as syrup, you can pasteurize it at 63 °C for 30 minutes or 72 °C
for 15 seconds before closing in clean bottles. However, you may instead like
to take your syrup on a longer journey. For this the options are endless, so I
will not give you super precise instructions – also because when I made the
best version of this, I was not in ‘lab mode’ and have no written record of any
recipe, and it was done by feel. Unrepeatable – as the very best things so
our pollen-dusted hands after picking many bags of elder flowers
I’d like to tell you how
to turn this into floral vinegar with a gentle acidity and some sweetness,
suitable for diverse applications from desserts to sauces and cocktails. This
is somewhat similar to a ‘shrub’, but I have never tasted a shrub this good. The fact that it
goes through two layers of fermentation, alcoholic with the flowers and acetic
with the berries, leads to completely new levels of complexity.
To make your syrup into a
wine (the first stage in vinegar-making), dilute it down to around 20% sugar
(more to have it sweeter/stronger, less to have it more dry/weaker – dependent
on the yeast strains being used), give it a shake to dissolve some oxygen and
pitch (add) some yeast. Put an airlock on this and leave it somewhere cool to
ferment and forget about it for a while. For more information on alcoholic
fermentation, check here.
So in 2010 after tasting
my over-sweet, but quite alcoholic and rather nice floral wine, I decided I
wanted to make vinegar that had serious aging
potential. I’ve been quite obsessed
with vinegar for quite some time, so there are a few posts written about it
around on this blog. For simple European vinegars see here, processing methods here and balsamic style vinegars, here.
Back to my elder vinegar,
and how to get it older. The ‘wine’, as it stands, has a very simple mixture
(sugar, water, acids, floral and lemon flavours and alcohol). In order to give
the vinegar aging potential it required some structure, tannins and
antioxidants. Of course, elderberries are rich in all these things, so it made
sense to give the flower wine structure using fruits of the same plant.
So, hold the wine until
the elder berries are ripe and deep purple. Then pick loads and loads of the
biggest, juiciest berries, and fill up a wide mouthed jar with them. This works
well with elderberries, but also with blackberries and other colour-rich
berries that will give aging potential to your vinegar. Cover the berries with
your elderflower wine, and add about a quarter of this quantity again of live
It’s important to use a
wide-mouthed jar to increase oxygen circulation, and don’t use a lid but a thin
piece of muslin or similar. Keep your slowly processing vinegar in a warm and
dark place (between 30 – 40 °C is great). Leave it for
1 month like this. After that time, strain to remove the berries, return to the
jar and put back in your warm and dark place for another two months.
Don’t worry if you remove
the vinegar mother while straining. Although the mother is attached to lots of
superstition, it is a recognizable manifestation of the acetic acid bacteria,
but the bacteria are plentiful in the liquid, and that’s quite enough! For more
information on the formation of mothers, and how that works, have a look at
this excellent post on the acidic beverage kombucha.
There is one problem, and
that is that elderberries can be toxic. In fact the whole elder plant is pretty
full of a family of molecules called cyanogenic glycosides – which are
particularly potent in the green parts and the seeds. For more informations on
this, you can refer to Justine’s post on hygrogen cyanide. This is why it is
crucial to separate the green parts from the flowers when making the syrup.
But then we get to the
berries. If one drinks a freshly made elderberry juice, and we tried it, chances
are that one is going to feel bad for a little while – to quote René,
reflecting on a spoonful of raw elderberry juice, “you know the feeling of car
sickness, it’s like that but times 100, it’s like hitting a brick wall of
nausea, with immediate effect” – and we
are now older and wiser. So don’t try raw elderberry juice.
So I wanted to find out
more about cyanogenic glycosides, and knew that people who had tried the
berries had felt very sick, but that people who tried my vinegar had a massive
we have Justine here at the lab, and she’s great at the chemistry side of things,
so she’ll fill you in on that.
And yeah, I know Elderflower season is over, but we’ll repost this at the start of next year’s season!
Part 2: Is this vinegar safe?
by Justine de Valicourt
here is a long tradition
in many areas of the world, particularly Africa and South Africa, of eating
cassava. Cassava has one of the highest concentrations of cyanogenic glycosides
and it is often the cause of massive food poisoning in regions with drought or
famine. Cassava products are harmful mostly in these moments because people are
consuming it immediately, before it is properly processed. This root should
always be cooked after being previously soaked and fermented. The fermentation
lowers the pH and therefore also the potential release of cyanide from the
glycosides (White, 1998).
Glycosides are molecules
that include a sugar and another functional group. In the case of cyanogenic
glycosides, the functional group is partly composed of a molecule of cyanide.
They are concentrated in vacuoles (small bubbles distributed throughout the
cytoplasm of the cell). When the cell is harmed, the bubbles break and the cyanogenic
glycosides are released into the cytoplasm, where they can react with enzymes
that will break the bond between the sugar molecule and the functional group.
The free cyanide then begins its disturbance of cellular respiration.
The cyanogenic glycosides
in elderberries are different from the ones in cassava, but a study from Eugeniusz
Pogorzelski (1982) also showed that
fermentation lowered the cyanide potential of elderberries. Enzymes are
proteins, and acidity does the same to them as to fish in ceviche or as heat
does to an egg: it denatures them. Enzyme then become inefficient at breaking
the bond between the sugar and the cyanide and the cyanide stays harmless. So,
the low pH of the vinegar might be enough to lower the cyanogenic potential of
the berries. Could explain the smile…
Also, as hydrogen cyanide
evaporates at 26°C, a big part of the free cyanide should be released in the
second fermentation that occurs around 30-40°C.
and importantly, nobody ever drinks an entire glass of vinegar.
So the vinegar is safe of
cyanide. Ours is in its second fermentation. It started to oxidise, with that
distinctive sherry taste, and a scent reminiscent of the floral notes on a
good sweet Moscato di Asti. Soon we will be smiling.
WHITE, Wanda LB, ARIAS-GARZON, Diana I., MCMAHON, Jennifer M., et al.Cyanogenesis in Cassava The Role of Hydroxynitrile Lyase in Root Cyanide Production. Plant Physiology, 1998, vol. 116, no 4, p. 1219-1225.
POGORZELSKI, Eugeniusz. Formation of cyanide as a product of decomposition of cyanogenic glucosides in the treatment of elderberry fruit (Sambucus nigra). Journal of the Science of Food and Agriculture, 1982, vol. 33, no 5, p. 496-498.