How Rum Is Made Video
7 minute read
This is where geography is important. Where you make rum or source the raw materials influences what rum is made.
We’ll start at the source, sugarcane. Grown in the Tropics, and harvested on location. Check out a producer’s profile to see when their harvest season is – Caribbean is January to June. So, if you want to see the process of making cane juice rum, it’s best to visit during harvest season.
Sugarcane has many varieties, some are named as colours red, yellow, or blue cane. Other varieties have sciencey names with letters and numbers – the first letter matches the country of origin’s first letter. Sugarcane grows 2 metres tall in an 18-month cycle.
During the dry season, farmers harvest cane by cutting it to a stub to achieve the highest sugar concentration and ensure regrowth. Some burn the cane fields to make it easier to harvest.
After cutting the cane it’s sent to the mill, where the lab tests its sugar concentration called Brix count. Sugarcane juice ranging between 18° to 22° Brix is optimum. After cleaning, the cane goes through mechanised rollers to squeeze the juice. Rollers, rain or late season high brix, and many other factors can all affect the juice going into rum.
Converting the Cane
Bagasse is a fibrous leftover material and is often used as a renewable energy to fuel boilers. The juice is filtered after milling. If making cane juice rum, it has to be sent to fermentation without delay before spoilage. Cane juice rum tends to be light, herbaceous, and grassy in character. For sugar, syrup & molasses, the cane juice is reduced by heating.
For molasses, after the juice is reduced in drying stages through several heating steps, when crystals start to form, they are skimmed out and processed for sugar, the remaining is molasses used for rum. Molasses undergo multiple centrifuge spins. Final molasses is stable and can travel, it doesn’t spoil.
Just like in school, there are grades of molasses; Grade A or Fancy molasses has the highest sugar content. Then, there’s Grade B or Choice. And, finally Grade C or Blackstrap molasses. Modern sugar factories have become so efficient at making sugar, which makes it harder to ferment the Grade C Blackstrap molasses.
Cane syrup is formed before crystals so not like molasses. It will turn into rock candy. But by slightly modifying the syrup chemically, it can stay as a syrup and be stable. It’s called high-test molasses (but it’s not molasses). In Guatemala to be labelled rum, the spirit must be distilled from fermented virgin cane honey, the concentrated syrup from the first pressing of the sugarcane. In Venezuela, Diplomático rum uses a blend of cane honey and molasses to make their rum.
Fermentation: Unlocks Flavour
For Molasses to ferment it needs to be diluted with water. Fermentable sugars remain in the molasses and will be consumed in fermentation by the yeast to create alcohol & CO2. Some, like Trinidad, use a propriety yeast that’s been nurtured for decades. Many modern distillers use a standard distiller’s yeast.
Like making bread, a starter yeast is often created to propagate and then added to the larger heated tanks of sugary water called mash. The ratios are monitored carefully to ensure the yeast survives and thrives. It can take 1- 4 days to create a ‘cane wine’ of strong beer strength. Shorter fermentation yields lower flavour compounds but higher alcohol at this stage than longer fermentation.
Some Jamaican distillers will ferment for up to a month to yield their desired style. A few artisanal distillers send half a fermented batch to be distilled and keep the other half to refill the next batch. There are lots of variables in rum making. High-ester rums like in Jamaica use cane acid, muck, and dunder. Check them out on the map
Cane acid is diluted with cane juice allowing more esters to form. Dunder is the leftover lees (or vinasse in French) in fermentation. This also increases the esters and other flavour compounds. Muck is a mix of bacteria and acid; it feeds on waste. It doesn’t smell good but surprisingly adds interesting notes like overripe bananas. Muck is only added after fermentation. Jamaican rum is limited to an ester level of 1600. In contrast, mainstream rums have ester levels of about 50.
Distillation – Concentrates Flavour
Following fermentation, the liquid is distilled, concentrating and refining the flavours. Distillation methods vary, including large-scale multi-column stills, and pot or column stills. Some distillers use both pot & column to achieve a balanced spirit. In Guyana, they even have wooden pot stills.
Batch distilling in a copper pot still creates a heavy distillate. In whisky, usually, there are 2-3 copper stills. In Caribbean rum distilleries, it’s often one pot still with a double retort for more interaction – acts like it has another still. Reflux removes unwanted sulfurs and retains desirable compounds. Each type of molecule evaporates at different rates. The shape of the neck and lyne arm affects the copper contact and resulting distillate spirit.
First off the still is what’s called the ‘heads’ these higher alcohols can be harmful. Then, the ‘hearts’ are what is kept as the main spirit run. Finally, the ‘tails’ are sent to be redistilled. In a distillery, it still takes art to know when these points are, and also the process of proofing down the alcohol. This requires a skilled eye and nose.
Continuous distillation or column stills are very tall stills consisting of a series of plates stacked upon each other. When heated, vapor rises through these perforated plates to meet the wash coming down. It is condensed and re-evaporates several times. This process removes heavier congeners (flavour compounds), producing a cleaner, more neutral distillate and high alcohol of 96%. In Cuba, the Spanish-speaking Caribbean distillers use this process to make light rum.
Creole column stills are used and were created on Martinique to produce Rhum Agricole. These stills can be modified into shorter column stills with fewer plates. This results in retaining more concentrated congeners than other column stills and alcohol off the still is 65%. To see the historical evolution of stills and engineering used in Martinique, it is well worth visiting the Saint James Rhum Museum.
It’s quite common for distillers to use a blend of pot and column to find the perfect balance in their spirit. And, some distillers blend distillates before going into the cask for maturation. Although not all rums are aged in a cask, some are bottled unaged.
Cask Drives Flavour
Maturation is a key step in flavour progression in rum. Many distillers adhere to strict laws of time aged in oak barrels. And, again geography plays its part. In the Caribbean’s hot and sticky climate, the maturation losses known as angels share are high. Even within one warehouse, casks can reveal different effects.
In High-altitude Guatemala and Mexico, cooler temperature slows down the losses. And, in Venezuela although humid, it has cooler night-time temperatures. These are regarded as Tropically aged rums. Compare that to rum aged in the continental climate of the European Northern Hemisphere which is much lower.
Regardless of where the barrels are, the rum inside reduces over time and interacts with the wood. The most common vessel for ageing rum is the 200-litre American standard barrel. This ex-bourbon cask, and brings vanilla, caramel, and fruit notes.
The Maestro Conducts the Orchestra
Master blenders, or Maestro/Maestra Roneros oversee the portfolio of casks, sometimes thousands of barrels. Their team monitor and are custodians of signature rum profiles, deciding what and when to blend for expressions that will be bottled. Many distillers will secondary age their rum or finish casks in Sherry or wines.
Some Spanish-influenced producers use the Solera system for ageing. This is where casks of differing ages are connected, some are removed to create a bottling, and the remaining casks are topped up to keep the process going. The essence is to maintain a perpetual spirit, and even profile regardless of when liquid is taken. It’s an active blend in maturation rather than blending casks afterward.
In Cuba, rum is filtered after ageing 2 years and aged further in a process for creating light rum, and a selection of aged rum. Chill-filtration is used by some distillers to remove the tiny particles that make a rum cloudy at lower temperatures. Distillers can also add caramel as a colour to adjust for consistency. And, before bottling the rum is diluted down, unless it’s cask strength of course.
10 Key Steps to How Rum is Made
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- Raw Material Preparation: Molasses, cane juice, or cane syrup undergoes processes before starting.
- Fermentation: Molasses, water, yeast & heat converts sugar to alcohol and carbon dioxide.
- Distillation: Heat evaporates the fermented wash to purify and concentrate the alcohol into a spirit.
- Dilution: Water is added to proof down the alcohol. This requires a skilled eye and nose.
- Barrelling: Spirit is sometimes blended pre-cask, and casks are charred and prepared before ageing.
- Ageing: Rum in oak barrels imparts flavour, colour, and aroma.
- Sensory Analysis: Blenders assess cask samples, nosing throughout the maturation.
- Blending: The master blender will marry different aged rums to create a marque or profile.
- Filtration/Dilution: Some producers filter and most will dilute the rum to bottling strength.
- Bottling: Bottle and label rum based on laws, its type, age, and alcohol content.
- However you enjoy rum, now you know a little more about it. We hope this quick & dirty guide helped you understand how rum is made.
Check out our other articles to explore the world of rum!
Sources and resources:
https://cocktailwonk.com/ https://therumlab.com/ https://www.rumcast.com/ https://rumporter.com/