From sugar cane to Rum in the Atlantic

When you think of rum — the West Indies, Venezuela and Brazil might come to mind. But before the first sugar cane cutting was even planted in the New World, sugar cane juice was already being fermented and distilled here in Madeira Island. Maybe as far back as the 1430's.

Sugar cane with an engine in the background. Photo by Jan Jokela

But before we really dive deep into this, let's start by explaining some of the nuances. There are really three broad styles when it comes to distilling fermented sugar cane molasses or juice:

• Rum: If you are not from a Portuguese or French speaking country, this is the style you are most used to. In the non-french West Indies, rum is produced by fermenting sugar cane molasses — which are then distilled. Sugar cane molasses are really a by-product of sugar production where by cooking the juice (garapa) over and over, you end up with a syrup that is more and more concentrated. After distilling, the typical rum is usually around 40% ABV.
• Rum Agrícola, Aguardente de Cana: In Madeira and in the French-speaking West Indies, rum is produced directly from fermented sugar cane juice instead of molasses, which results in a flavour profile that resembles much more the raw ingredient. These also tend to be quite a bit more expensive. In Madeira, the typical ABV concentration is 50–60%.

In the 16th century Portuguese settlers brought sugar cane cuttings from Madeira and began the cultivation of sugar cane in Brazil. They also brought their pot stills, giving birth to cachaça.

• Cachaça: This is by all means very similar to a Rum Agrícola in that it results from the distillation of fermented sugar cane juice, but usually with lower ABV 38–48% and a blander flavour profile that is mostly associated with large scale productions that sell cachaça as a very neutral spirit to be used in cocktails. Smaller ventures however produce quite interesting stuff.

So let’s get started and make the best Rum you’ll never get to taste!

But first things first: freshness. This means cutting the cane in the morning and putting your engine to work early in the day. All an engine does is really to apply rotation and pressure to two cylinders that will break and press sugar cane, separating the juice from (most) of the solid parts.

Engenho—Portuguese for engine—is no more no less than a sugar cane mill, and by definition, you are an engineer if you can build one.

Fermentation

In the tropics, it is not unusual to get sugar cane juice with 20–24º in the Brix scale (the sugar concentration, which provides us with an idea on the ABV level once fermentation is complete). As we are a bit further north however, we are lucky to get 16–18º. This in not entirely a bad thing —as producers in Brazil often add water to reduce the Brix level down to 16–18º, so by having sugar cane available with these characteristics out of the box, we are making sure we are not diluting the aromas.

Earlier, I mentioned that an engine splits the the liquid part (garapa) from the solid outer shells. We are still left with quite a bit of the fibres from the sugar cane however. Now—commonly one would filter all the garapa to make sure all solids (bagacilho) are discarded, as it is often argued that these remaining solids can potentiate unpleasant consequences. But I disagree. From my experience this has resulted in quite the opposite: Rum that is significantly more packed with complex aromas than most commercial products.

That said, what should we do next? Pasteurise and then ferment for 12 to 24 hours in 28–32ºC, right?

No. We are doing none of that. We are:

• Adding simple bread yeast (2gr/l).
• We won’t be pasteurising, we want some of those wild yeasts competing at the beginning.
• We will very gently let it ferment for 2 to 3 weeks at 17–22ºC. You read correctly. 2 to 3 weeks.

Sugar cane juice in a stainless steel vat. Photo by Jan Jokela

Distillation

After a couple of weeks, we should see diminished activity and Brix readings a hair below 5º. Now— commercial rum is distilled using column stills, which are more productive by an order of magnitude. However, coppers pot stills output much more congeners than these large scale column stills, which will help us achieve fuller tasting rums with much of the taste and aroma that we achieved during fermentation.

If you are wondering how a pot still works, the mechanism is fairly simple: the fermented juice (garapa) is heated to boiling point, and as the vapour tries to escape, it is subjected to a circuit that is water cooled, resulting in condensation.

As the alcohol is the first to evaporate, you usually start by getting almost pure alcohol which then decreases in ABV as distillation proceeds. I usually discard the first glass and stop distillation when the average ABV of the batch drops to what I want (usually 50–60º ABV).

In the Brazilian state of Minas Gerais, there is an interesting adaptation to the copper pot still which directly pours cold water on the pot still head (the top), causing immediate condensation (instead of a serpentine circuit). This would be quite interesting to try as you can in theory capture even more of those congeners that accumulate at the pot still head.

Distillation using a copper pot still. Photo by Jan Jokela

Caninha

The end result is a Rum Agrícola that is interesting and complex in a way you can’t imagine if all you’ve tried are commercial brands of cachaça or rum—even the most expensive ones.

There is also a rich culture of ageing rum around here, traditionally in old wooden casks that have previously hosted fortified Madeira wine. But maybe more on that in a future post.