1. Introduction

Wine is a food product. Our common sense tells us that whenever we prepare food, we use clean utensils and surfaces. In the same way it is very important to follow sound cleaning practices around anything that comes in contact with your wine.

The aim of cleaning is to remove visible contamination; this may just be dust, cobwebs and light deposits through to caked on sediment and mould.

Sanitising is the step where you further treat a thoroughly clean surface or piece of equipment to reduce the level of microbes present to a level acceptable for the winemaking process.

Sterilisation is something that is beyond what we are trying to achieve for winemaking. Sterilisation refers to a surface being completely free of bacteria and other microorganisms. You certainly want this during surgical procedure, but not necessarily in the winemaking shed! Besides being practically impossible to achieve in a home winemaking situation, it is not even required to make great wines. The naturally high acid and alcohol levels present in wine make it an undesirable habitat for organisms that do us harm. 

Proper cleaning and sanitisation goes along way to ensuring your lovingly made wine does not develop nasty tastes due to organisms that, like us, happen to love living with wine! 

2. Cleaning and Sanitising Process

Cleaning and sanitising are separate steps; an effective sequence that is suitable for the home winemaking situation and applicable to anything that comes into contact with your wine is as follows:

1. Rinse equipment with clean flowing water
2. If have access to it, use hot water (50 to 70 C) on equipment that can tolerate it, otherwise cold water will do.
3. Use appropriate caustic cleaning agents for each type of equipment to remove scale and deposits. Thoroughly wet the surface to be cleaned with a generous quantity of the cleaning solution, scrubbing as required to remove deposits. Persistent deposits may need soaking.
4. Sanitise with a suitable solution, generally Sulphur Dioxide/Citric acid based. Flood the surface to be sanitised with a generous quantity of the sanitising solution leaving it in contact for a few minutes.
5. Rinse all sanitised equipment with cold water.
6. Drain all cleaned and sanitised equipment so that there little, preferably no residual water.

It is important that all equipment treated in this way be dry, completely free of any solids and with no remnant smells.

New and previously cleaned equipment that has no solid deposits may not need treatment with a cleaning solution. A rinse with clean water to remove dust and cobwebs is all that is required for the cleaning step in this case. The sanitisation step must then be performed as described above.

The most appropriate cleaning solution to use is Sodium Percarbonate, also known as Oxyper. It is readily available at home wine and brewing shops and is inexpensive.  Avoid using Chlorine, soap and detergent based cleaners, perfumed cleaners, as these are difficult to rinse away thoroughly, plus there is the ever present risk of impacting the taste of your wine.  Chlorine based cleaners are to be particularly avoided for the beginning home winemaker as Chlorine is contributing factor for "cork taint"

Make up a cleaning solution by dissolving Sodium Percarbonate at a rate of 8 to 12 grams (three level teaspoons) per litre in clean water. It is best to dissolve your measured dosage in a small amount of hot water and then mix with cold water for the desired volume of cleaning solution.

There are many commercial variants of Sodium Percarbonate based cleaning agents. So check the recommended dosage on the packet of whatever you purchase. The main thing is to ensure that you purchase a caustic-based cleaning agent containing NO chlorine, soap or detergent.

3.2 Sanitising Solutions

Potassium Metabisulphite (PMB) is the most widely used and effective sanitiser for winemaking. Its sanitising effectiveness is enhanced with the citric acid. The acid content of a Sulphur-Citric sanitising solution also serves to neutralise surfaces previously cleaned with caustic solution.

An effective sanitising solution can be made by dissolving 17 grams of PMB (3 level teaspoons) in 1 litre of water. This is best made by dissolving the measured dose of PMB powder in 500 millilitres of warm water, and then add cool water to make 1 litre of sanitising solution. To make Sulphur-Citric solution add 17 g (3 teapoons) of Citric Acid to the PMB solution.

As an alternative to Sulphur-based sanitising solution there are “non-rinse” solutions that are based on compounds that produce hydrogen peroxide when dissolved in water. Hydrogen Peroxide acts as a strong oxidizer, killing microbes as it bubbles in vats, hoses and barrels. Its bubbling action makes it especially good for hard to scrub places like the inside of siphon hoses. Like Hydrogen Peroxide, however, it does need an acid rinse in order to neutralize the surface.

Proxitane and Brewshield are liquid, Hydrogen Peroxide-based sanitising solutions that are readily available from home winemaking and brewing shops. Finally, there are iodine-based sanitisers such as iodopher.

4. Safe Handling of Cleaning and Sanitising Solutions

Always wear gloves when preparing, mixing and using cleaning and sanitising solutions. Remember the cleaning solution is caustic and will irritate and possibly burn sensitive skins.

Always use Sulphur-based sanitising solution in a well ventilated area; Inhaling Sulphur fumes that may be concentrated as you reach down into a fermentation vessel can cause throat and nose to become irritated.

5. Good cleaning and sanitising practices

1. Clean and dry equipment that is going into long-term storage;
2. Clean and sanitize a piece of equipment before you use it;
3. Clean well, making sure no colour or smell remains;
4. Clean up wine spills as soon as they occur as they will attract insects and microorganism that are harmful to wine

References:

1. Rankine, B. Making Good Wine, 2004
2. Pambianchi, D. Techniques in Home Winemaking, 2008
3. Crowe, A. The Winemakers Answer Book, 2007