What is a Demijohn and How Much Does it Hold?

Demijohns are used to ferment beer and wine and are usually made of glass. But how much does a demijohn hold? Why are they that shape? We give you all the facts.

BREWING EQUIPMENT

Brewpedia

9/4/20239 min read

What is a Demijohn and How Much Does it Hold?

A demijohn is a large container traditionally used for fermenting and storing beverages like wine, cider, and beer. Understanding its capacity is crucial for anyone involved in the brewing and fermentation process.

A standard demijohn typically holds 4.54 litres (1 gallon) of liquid.

However, its capacity can vary, with some demijohns having the ability to hold way beyond that.

This article will provide an in-depth understanding of demijohns, their capacities, and their importance in the beverage making process.

What is a Demijohn?

A demijohn is a glass or plastic container with a narrow neck, often used for fermenting and storing liquids such as wine, cider, beer, and spirits. It is a crucial accessory in homebrewing and is also known as a demijohn bottle or a glass carboy.

Demijohns are perfect for fermenting liquids as they provide a secure and sealed environment, preventing bacteria and contaminants from entering while allowing carbon dioxide to escape during fermentation.

How Much Does a Demijohn Hold?

The capacity of a demijohn varies, but it typically holds around 4.54 litres (1 gallon) of liquid. However, there are demijohns available in different capacities, ranging from 1 gallon (4.54 litres) to 15 gallons (68 litres).

This means you can choose a demijohn that fits your needs, whether you are making wine, cider, or beer at home.

Why is Glass Preferred for Demijohns?

Glass demijohns are often preferred over food grade plastic ones for several reasons that ensure the quality and taste of the beverage during fermentation and storage.

  1. Non-porous Material: Glass is non-porous, meaning it does not have tiny holes that allow air or liquid to pass through. This is crucial for the fermentation process as it ensures that no oxygen, which can spoil the beverage, enters the demijohn, and no carbon dioxide, produced during fermentation, escapes except through the airlock.

  2. No Absorption of Odours: Glass does not absorb odours or flavours from the beverages stored in it. This ensures that the taste and quality of the beverage are not affected during fermentation and storage. This is particularly important for those who use the same demijohn for different types of beverages.

  3. Easy to Clean: Glass surfaces do not scratch easily, which makes it easier to clean and sanitise. Scratches can harbour bacteria and other contaminants, so a smooth surface is essential to maintain cleanliness.

  4. Observing Fermentation: Glass demijohns are perfect for observing the fermentation process as they are usually made of clear glass. Being able to observe the fermentation process allows you to check for any issues such as stuck fermentation or infection without having to open the demijohn.

  5. UV Light Protection: Some glass demijohns are made of coloured glass, usually amber or green, which helps protect the contents from UV light. UV light can cause unwanted chemical reactions in the beverage, affecting its taste and quality.

  6. Reusability: Glass demijohns can be used repeatedly for a long time if properly maintained. They do not degrade over time like plastic, which can become brittle and crack.

  7. Eco-friendly: Glass is recyclable and environmentally friendly. It can be recycled without losing its quality or purity, which is not the case with plastic.

While glass demijohns have many advantages, they are also heavier and more fragile than plastic demijohns. It is important to handle them carefully to avoid breakage.

Additionally, glass demijohns are usually more expensive than plastic ones, but many homebrewers and winemakers believe that the benefits of glass outweigh the extra cost.

How are Demijohns Used in Beer Homebrewing?

Demijohns are perfect for the beer homebrewing process as they serve as an essential vessel for both fermentation and storage of beer. Here is how a demijohn is typically used in beer homebrewing:

  1. Primary Fermentation: After the wort (unfermented beer) has been prepared and cooled, it is transferred to a demijohn for primary fermentation. This is the stage where yeast is added to the wort, and the fermentation process begins. The demijohn is sealed with a bung or cork and an airlock to allow carbon dioxide to escape during fermentation while preventing contaminants from entering.

  2. Secondary Fermentation: After primary fermentation is complete, the beer is usually transferred to a second demijohn for secondary fermentation. This is done to separate the beer from the sediment that has accumulated at the bottom of the demijohn during primary fermentation. Secondary fermentation helps to clarify the beer and improve its flavour.

  3. Ageing: After secondary fermentation is complete, the beer can be left in the demijohn to age. Ageing the beer allows the flavours to mature and develop, resulting in a better-tasting finished product.

  4. Bottling: Once the beer has aged to the desired level, it is transferred from the demijohn to bottles or kegs for storage and serving.

It is important to ensure that the demijohn is thoroughly sanitised before use to prevent contamination of the beer. Additionally, it is essential to use an airlock during fermentation to allow carbon dioxide to escape and to prevent bacteria and other contaminants from entering the demijohn.

How is a Demijohn Used in Wine Making?

In wine making, a demijohn is used at various stages of the process including fermenting grape juice, ageing the wine, and sometimes even for storage.

  1. Fermenting Grape Juice: The first step in making wine is fermenting the grape juice. The demijohn is filled with grape juice, and then yeast is added to initiate fermentation. The yeast converts the sugars in the grape juice into alcohol and carbon dioxide. The demijohn is sealed with a bung or cork and an airlock. The airlock is essential as it allows carbon dioxide to escape during fermentation while preventing contaminants like bacteria and wild yeast from entering. This is crucial as any contamination can spoil the wine.

  2. Secondary Fermentation: After primary fermentation is complete, the wine may undergo a secondary fermentation to convert any remaining sugars and to allow the sediment to settle. The wine is transferred, or 'racked,' from the first demijohn to a clean demijohn, leaving the sediment behind. This process helps to clarify the wine and may also improve its flavour.

  3. Ageing: Once the fermentation is complete, the wine is left to age in the demijohn. Ageing allows the flavours in the wine to mature and develop. It is important to store the demijohn in a cool, dark place during this time to protect the wine from light and temperature fluctuations. The length of time the wine is aged will depend on the type of wine being made and the desired end result.

  4. Storage: Some winemakers choose to store their wine in demijohns until it is ready to be bottled. This can be a short-term storage solution before bottling, or the wine can be stored in the demijohn for a more extended period to allow it to age further.

  5. Bottling: Once the ageing process is complete, and the wine has reached its desired maturity, it is transferred from the demijohn to wine bottles for storage and serving.

It is essential to ensure that the demijohn is thoroughly cleaned and sanitised before use to prevent contamination of the wine.

It is also smart to regularly check the demijohn during the fermentation and ageing processes to ensure that it remains sealed and that the airlock is functioning correctly.

What is the Difference Between a Demijohn and a Carboy?

A demijohn and a carboy are similar in shape and function, but there are subtle differences between the two. A demijohn is a glass or plastic "container" with a narrow neck used for fermenting and storing liquids.

A carboy, on the other hand, is a large glass or plastic bottle with a narrow neck used for the same purposes. The main difference between the two is the material and the shape.

Demijohns are usually made of glass and have a round or oval shape, while carboys can be made of glass or plastic and have a more cylindrical shape.

What are the Accessories Needed for a Demijohn?

To use a demijohn effectively, you will need a few accessories. First, a bung or cork is necessary to seal the demijohn's neck. This will prevent contaminants from entering while allowing carbon dioxide to escape during fermentation.

Next, an airlock is essential for fermentation. It is a device that is filled with water and attached to the bung or cork. The airlock allows carbon dioxide to escape while preventing air and contaminants from entering the demijohn.

Additionally, a rack or stand may be needed to elevate the demijohn and facilitate the transfer of liquids.

How to Check if a Demijohn is Secure?

To ensure that a demijohn is secure, check that the bung or cork fits tightly into the neck of the demijohn. Also, ensure that the airlock is properly attached to the bung or cork and is filled with water.

This will create a seal that prevents air and contaminants from entering the demijohn while allowing carbon dioxide to escape during fermentation.

Additionally, check that the demijohn does not have any cracks or damages that could compromise its integrity.

What is the Etymology of Demijohn?

The term 'demijohn' comes from the French word ' dame-jeanne ', which translates to ' Lady Jane '.

It is believed that the name was given to the container because its shape resembled the dresses worn by women in the 16th and 17th centuries.

Over time, the name evolved from dame-jeanne into 'demijohn', which is now commonly used in English-speaking countries.

How to Choose the Right Demijohn?

Choosing the right demijohn depends on several factors. First, consider the capacity of the demijohn. Demijohns come in various sizes, ranging from 1 gallon (4.54 litres) to 15 gallons (68 litres).

Choose a size that fits your needs and the quantity of liquid you plan to ferment or store. Next, consider the material of the demijohn.

Glass demijohns are preferred for fermenting and storing beverages as they do not scratch easily, do not absorb odours, and are easy to clean.

However, plastic demijohns are lighter and less fragile, making them easier to handle and transport.

How to Clean and Maintain a Demijohn?

Cleaning and maintaining a demijohn is crucial to ensure its longevity and the quality of the beverages it contains. If not cleaned properly, residues from previous brews or contaminants can affect the taste and quality of your wine or beer.

  1. Cleaning a Demijohn:

    • Remove Residue: Empty the demijohn and rinse it with warm water to remove any loose residue.

    • Scrubbing: Use warm water and a mild detergent or a special demijohn cleaner. Scrub the inside of the demijohn with a long-handled brush to remove any residues or deposits. Make sure to clean every corner of the demijohn.

    • Rinsing: Rinse thoroughly with clean water to remove all detergent residues. It may be necessary to rinse several times to ensure all detergent residues are removed.

    • Sanitising: To sanitise the demijohn, use a food-grade sanitiser or a solution of 1 tablespoon of bleach to 1 gallon of water. Make sure to cover all surfaces of the demijohn with the sanitising solution. Leave the sanitising solution in the demijohn for the recommended time on the sanitiser instructions, then rinse thoroughly with clean water.

    • Drying: Let the demijohn air dry completely before using it again. Make sure it is thoroughly dry to prevent any bacterial growth.

  2. Maintaining a Demijohn:

    • Storage: Store the demijohn in a cool, dry place away from direct sunlight. Sunlight can cause the glass to weaken over time and can affect the taste of any beverages stored in the demijohn.

    • Regular Checks: Check the demijohn regularly for any damages or defects. Look for cracks, chips, or scratches in the glass. Even a small crack can lead to a leak or can cause the demijohn to break when filled with liquid.

    • Replacing Accessories: Over time, the accessories like bungs and airlocks can wear out or become damaged. It is essential to replace these accessories as needed to ensure a proper seal and to prevent contamination.

Remember, a clean and well-maintained demijohn will ensure the quality of your beverages and will last for many years.

Can a Demijohn be Personalised?

Yes, a demijohn can be personalised to make it a unique accessory for your homebrewing setup or a special gift for a loved one. Personalisation can be done by painting the glass, attaching a custom label, or engraving the surface of the demijohn.

However, it is important to ensure that any paint or adhesive used is food-grade and will not affect the contents of the demijohn. Additionally, any personalisation should not obstruct the view of the liquid inside, as observing the fermentation process is crucial for making high-quality beverages.

How to Transfer Liquid from One Demijohn to Another?

Transferring liquid from one demijohn to another is a common practice in homebrewing, especially during the racking process. Racking is the process of transferring liquid from one container to another, leaving the sediment behind. To transfer liquid from one demijohn to another, you will need a syphon or a racking cane. Here are the steps to follow:

  1. Elevate the demijohn containing the liquid so that it is higher than the empty demijohn.

  2. Sanitise the syphon or racking cane and insert it into the demijohn containing the liquid, being careful not to disturb the sediment at the bottom.

  3. Start the syphon by sucking on the end of the tube until the liquid starts to flow. Quickly insert the end of the tube into the empty demijohn.

  4. Allow the liquid to flow from one demijohn to the other until all the liquid has been transferred and only the sediment remains in the first demijohn.

  5. Remove the syphon or racking cane and seal the demijohn with a bung or cork and an airlock.

Important Things to Remember:

  • A demijohn typically holds around 4.54 litres (1 gallon) of liquid, but its capacity can vary.

  • Glass demijohns are preferred for fermenting and storing beverages as they do not scratch easily, do not absorb odours, and are easy to clean.

  • A bung or cork and an airlock are essential accessories for a demijohn.

  • The term 'demijohn' comes from the French word 'dame-jeanne', which translates to 'Lady Jane'.

  • To clean a demijohn, use warm water and a mild detergent, and then sanitise it with a food-grade sanitiser or a bleach solution.

  • Store the demijohn in a cool, dry place away from direct sunlight and check it regularly for any damages or defects.