How to Make 1,000 Litres of Molasses Rum Wash the Easy Way!

How to Make 1,000 Litres of Molasses Rum Wash the Easy Way!

Dermott DowlingOct 24, '23

The Australian sugar industry produces raw and refined sugar from sugarcane. Around 95 per cent of sugar produced in Australia is grown in Queensland and about five per cent in northern New South Wales, along 2,100 km of coastline between Mossman in far north Queensland and Grafton in northern New South Wales.

More that 80% of all sugar produced in Australia is exported as bulk raw sugar, making Australia the second largest raw sugar exporter in the world. In recent years, Asia has become a major focus with key export markets including South Korea, Indonesia, Japan and Malaysia which are our most important markets.

A natural byproduct of the sugar making process is molasses.  Molasses is a thick, dark syrup made during the sugar-making process. First, the sugar cane is crushed and the juice is extracted. The juice is then boiled to form sugar crystals and removed from the liquid. The thick, brown syrup left after removing the sugar from the juice is molasses. This process is repeated several times to produce a different type of molasses each time.  Molasses is a blend of sugar, cane solids, and some water.

Australia has a natural competitive advantage for craft Rum producers especially, those located in Queensland and northern New South Wales given our abundant supply of sugar and Molasses.  Here we will share a basic introduction and guide to make 1,000 litres of Rum Wash from Molasses.


Crafting rum wash from molasses is the foundational step in rum production. This guide will walk you through the process of making 1,000 litres of high-quality rum wash, which will serve as the basis for your rum distillation.

Before you start, ensure you have the necessary ingredients and equipment:



The key ingredient for your rum wash. Choose high quality molasses, as it significantly influences the flavour of your final product.  At we offer two types of high quality Molasses for Rum Distillers:

Individual batch certificates of analysis are available for the Bundaberg Refinery Molasses (Food Grade) and season production certificates are available for the Organic Molasses.  Both are available on the product pages.  Brix are typically 78-85% for the Organic Molasses and 76-81% for the Refinery Molasses.


Select a suitable yeast strain based on your desired rum style. Options available from include DistilaMax® RM, DistilaMax® CN, DistilaMax® SR, or SafSpirit™ C-70.  Every yeast will have its own unique Congener profile and we recommend you refer to the product information on each page, the technical specifications and results from fermentation trials performed by the yeast manufacturer before choosing the yeast for the style of Rum you would like to produce.  Follow the instructions in terms of dosage and rehydration processes on the technical specifications listed on the products pages as well.

Rehydration Aids:

We recommend using products like Lallemand Go Ferm Protect Evolution to assist with yeast rehydration.  Rehydration aids provide the yeast with a high amount of sterols, vitamins and minerals. Significantly improves yeast vitality and aroma precursor assimilation giving your yeast maximum chances of a healthy vigorous fermentation.  Health Yeast = Delicious Rum Wash!

Buffering Agents

Controlling the pH of your fermentation is also vital to ensuring a happy and healthy yeast and a clean fermentation with the desired esters as opposed to sulphur and other volatiles that unhealthy yeast will exhibit during a stress fermentation. If the pH is let to go too low you may also suffer from a stalled fermentation or stuck fermentation.  We recommend potassium bicarbonate or sodium bicarbonate or, at a rate of 1g per litre (per final volume) to control pH.  The buffering agents may be added at the start of fermentation or staggered with your yeast nutrients depending on which fermentation process your going to follow.  More on the process later in this blog.

Yeast Nutrients and DAP

Molasses has more nutrients and trace minerals than refined sugar however it is still necessary and vital that you feed your yeast with the essential minerals and vitamins to aid their healthy development and insure you have a successful fermentation.  Options available to use include a combination or complete Yeast nutrient like DistilaVite® GN which contains a proprietary blend of inorganic nitrogen (diammonium phosphate), organic nitrogen (free amino nitrogen derived from inactivated yeast), and key vitamins and minerals including thiamine, niacin, folic acid, magnesium sulphate and calcium pantothenate. DistilaVite® GN also provides sterols and unsaturated fatty acids, which lend alcohol resistance to the yeast.

Alternatively, some of our customers will use a wine yeast nutrient like FERMAID® O or and diammonium phosphate or FERMAID® AT


Fermentation Vessel: A large, cleaned, rinsed and sanitised ideally conical fermenter with sufficient capacity to hold and ferment your 1,000 wash.  Temperature control is vital to clean, consistent fermentation and yeast health so invest wisely in your fermentation vessels.  The ability to oxygenate your fermenter and agitate a wash is also helpful if you're doing any high fructose or sucrose washes that can easily stress Yeast.

Hydrometer and Thermometer: To monitor and measure the wash temperature.  There are a number of floating measurement devices available now that can assist with measuring and reporting in real time your fermentation.  Some are listed below:

Refractometer: To measure sugar content (Brix) and monitor fermentation progress. Many professional brewers and distillers prefer to use a Refractometer to a Hydrometer for the speed and accuracy of measurement and ability to take small samples to test continuously during a fermentation.  Some options include:

pH Tester: Equally important to monitoring the sugar content (brix) of the fermentation is the pH and we recommend you invest in a quality pH tester from a reputable supplier.  We sell a number on our website and a popular choice for its dual functionality is listed below:

Multi-purpose measurement tools: We have seen the rise of some affordable and reliable measuring devices for the serious home brewer and distiller or small craft brewer and distiller that measure multiple key metrics from a small sample using a single device.  One example is listed below:

Stirring and Mixing Tools: For uniform distribution of ingredients.  Again we encourage you to consider seriously before purchasing fermenters and mashing and/or mixing tools all the various products you intend to produce in your distillery.  Upfront investment in capital that can heat, mix and insulated fermentation vessels will ensure you have maximum chance of creating clean, pure and consistent craft spirits in your Distillery.

The Fed-Batch Fermentation Process - Method #1

Optimising Fermentation for Highest Ethanol Yield using Lallemand Biofuels & Distilled Spirits Guideline


Step 1:

Fermentation (Fed Batch): For 1,000L, Fermentation time: 28-36 hours, Temperature: 32°-34°C

Step 2:

  • Add the rest of the water to your fermenter + 30% of the molasses (700 L of water and 75 L of Molasses)

Step 3:

  • After 10 hours, add 40% of the molasses (95 L of Molasses)

Step 4:

  • After 10 hours, add last 30% of the molasses (75 L of Molasses)


Step 5: Distillation

The Staggered Nutrient Fermentation Process - Method #2

Yeast Rehydration

Step 1:

Lallemand Biofuels & Distilled Spirits recommends the rehydration of DistilaMax® RM, DistilaMax® CN, and DistilaMax® SR.  Refer to product pages for each specific yeast rehydration protocol.  Rehydrate your selected yeast strain as per the manufacturer's instructions. Consider using Lallemand Go-Ferm Protect Evolution™ aids for optimal yeast health.

  1. For rehydration, use a clean container. Do not use demineralized water.
  2. Rehydrate the yeast in clean water (the water should be 10 times the weight of the yeast and at a temperature of 32°C - 36°C).
  3. Suspend contents carefully by gently stirring and then wait for 15 - 20 minutes maximum (minimum 10 minutes) before moving onto the next step.
  4. Add this preparation to the wash. If there is a temperature difference of more than 8°C between the wash to be inoculated and the rehydration solution, add some wash slowly into the rehydration solution to reduce the temperature difference.

Molasses Wash Preparation

Step 2:

Mix the full contents of 250 litres (approx. 350Kg) molasses with 750 litres of water.  Measure the Brix (starting gravity).  Buffer the pH to ideal fermentation starting pH 4.5 - 5.0.  Use citric acid to bring the pH down and potassium bicarbonate to bring it up as necessary.

Add the rehydrated yeast to the wash and gently stir for even distribution. Add ⅓ of your Yeast Nutrients and DAP

Fermentation (Staggered Nutrient and Buffering Batch): For 1,000L, Fermentation time: 72-96 hours, Temperature: 30°-32°C

Step 3:

Cover the vessel and maintain a warm temperature between 25-35°C during the initial fermentation period. Allow this stage to proceed for 12-24 hours.  Note: the lower the wash fermentation temperature the slower the fermentation and the less esters the yeast will produce. Likewise the warmer the fermentation the faster the fermentation and the more esters the yeast will produce.  Most professional distillers yeasts are designed to run at the upper range of their optimal temperature range.  Please always refer to our product pages and technical data sheets for this information.  We would recommend that you run around 32°C if you can control the temperature effectively.

Step 4:

After the initial 24 hours, measure the Brix (gravity) and pH, degas as necessary and Buffer the pH back to the ideal fermentation range for your Yeast (refer to product pages and technical data sheets).  You will note many professional Rum Distillers yeast are highly pH tolerant and you will see pH drop naturally as fermentation progresses.  Use citric acid to bring the pH down and potassium bicarbonate to bring it up as necessary.  Try not to overdose your pH buffering aids as they will have an impact on flavour of the wash in high dosages.

Add the next ⅓ of your Yeast Nutrients and DAP

Step 5:

After an additional 24 hours, (48 hours total) measure the Brix (gravity) and pH, degas and oxygenate as necessary and Buffer the pH back into the ideal fermentation range for your Yeast (refer to product pages and technical data sheets).

Add the final ⅓ of your Yeast Nutrients and DAP


Step 6: Distillation


Following this guide will allow your craft distillery to produce 1,000 litres of rum wash from molasses. Remember that crafting exceptional rum involves patience and experimentation. The quality of your ingredients, yeast selection, and attention to detail throughout the process will influence the unique flavours and characteristics of your final rum.

As you proceed with fermentation, make notes and adjustments to refine your process for future batches. Continuously learning and improving your techniques will lead to the creation of exceptional craft rum.  In future blogs we will discuss in greater detail the distillation techniques and use of Dunder, Muck and other interesting ways to really make your Rum Shine!  Cheers #DistilSafely and please do not hesitate to reach out to us at anytime to discuss your brewing and distilling needs.