Proper cleaning and sterilisation for home brewers

Proper cleaning and sterilisation for home brewers

This article originally appeared on mousecleaning (no longer online) and was written (by us) to address a common problem of bio-contamination during fermentation. However, the principles behind this article are exactly the same for commercial operations of any size. More often than not the sterilisation agents will be different for commercial uses, but the principle of the minimum dwell time is the same.

There is an undeniable pleasure in carefully planning and crafting your own beer or wine. You can picture in your mind what the taste should be like, even if you’ve taken the easy option with a beer or wine kit, what you are hoping though, is that the final product lives up to the marketing and your expectations. There is an awful amount preparatory work that goes into making a homebrew, that is even before the yeast has been pitched: all the equipment and fittings must be clean and sterilised, and that includes any ancillary piece of equipment or fitments that could come in contact with the liquor. It is obvious that the demijohn or fermentation bucket must be clean and sterilised, but how often is the thermometer, sieve or bungs missed out? Maybe they are given a cursory clean? Maybe a proper clean from the previous batch has been shortened (or missed out) and the sterilisation step has been all too rapid.

Mistakes and short cuts in the cleaning and sterilisation steps can lead to fungal and bacterial contamination which will spoil your entire batch. So, trying to save a few minutes, or even just being plain lazy could jeopardise weeks and months of work. You would be forced to ditch your entire brew and start again, think of the wasted effort – it’s quite soul destroying.

To combat contamination you need to understand and appreciate the importance of cleaning and sterilisation as two separate processes, yet each step is critically important and cannot be taken lightly. Before sterilisation can start, the piece of equipment or fitment must be clean – this is the first absolute requirement.

The second absolute requirement is that the items must be in direct contact with the sterilisation liquid for the minimum dwell time, preferably longer.

The first requirement begs the question: What is clean? How do we know when the item has been cleaned to right standard? Cleaning is all about lifting and removing foreign material from a surface, this material could be anything: dirt, oil, greases, proteins, fats, powders, anything that clears doesn’t belong. But this foreign material also includes bacterial or fungal colonies that have become attached to the surface or other materials through the excretion of biofilm (the actual process is a little more complicated). Biofilm is a fine web that encapuslate the bacteria and protects them against harsh environmental conditions; we see the end result as a grey-black mass (mold is a fungus) in the corners of showers, toilets, bottles, anything that isn’t cleaned and gets wet. The process of cleaning, therefore, requires that this mass build up be broken down and removed, exposing the underlining bacteria or fungus to the sterilisation step. If this not done, biofilm can protect the bacteria from the sterilisation liquid. Also, if the cleaning hasn’t been sufficient to remove all visible material, bacteria can harbour inside the material and gain protection much like biofilm. You now see why the first step – cleaning – is so important.

The second step – once the first step has been completed – exposes any contamination to biocides and fungicides, effectively killing any potential problems and ensuring the yeast can work. For this sterilisation to be guaranteed  the item must be in direct contact for the minimum amount of time specified by the manufacturer. This depends on the sterilisation agent and the concentration used, but the standard for home brewing is Sodium Dichloroisocyanurate (just look on the back of the packet) and this requires a minimum contact time of 30 minutes. Give the items a quick rinse with cold tap water (making sure that the water has been free-flowing prior) or cooled boiled water just before use.

By observing both these steps and being quite fastidious, you can guaranteed that perfect pint or glass of wine in a few weeks time – it only takes a few minutes longer during the initial stages, yet you will be dramatically cutting down on the risk of spoilage. Be fussy with your cleaning and sterilisation and clean and sterilise everything and anything that comes in contact with the liquor, no matter how brief that contact is. Don’t forget to clean your hands too: hands are an effective home and transport for bacteria.