It’s time we stopped using commodity caustic in Australia

Transient

Yes it’s cheap and it’s ubiquitous, but it may be doing damage to your wine and equipment, but let’s first look at the pros. Caustic is very good at quickly removing heavy deposits of wine solids with tartar whilst its pH is in the range 10-14 and used with potable water in ambient temperature range of 20-40°C.  These few benefits are the main reasons why it has become so widely used throughout the global wine industry.   

As caustic is a sodium product, it is potentially environmentally degrading (high sodium effluent can cause sodic soils), corrosive to most contact surfaces, creates high HR risk in use (burns to skin and eyes) and is not as an effective cleaning agent as you might think.  In addition to that, think of all of the extra paperwork and cartage cost required in transporting, on-site handling and storage; on site HR supervision; as well as the safety equipment required and maintenance for its use.

The pH differential between caustic and wine is 14 to 3.5 respectively, and the salt, whilst effective in decolourising and dissolving the organic soil, denatures and chars it at the same time (evidenced by red wine colour converting to a charcoal). At the same time, as a common salt derivative it increases surface tension which reduces likelihood of the removal of the protein.  When cleaning with caustic, often biofilm/protein char presents on surfaces after the process which requires large amounts of hot water and a mechanical action (high pressure pump spray) with task specific cleaning agents or often scrubbing in smaller tanks with only water (or a safe-to-use chemical) to simply to remove this film.  

With all of this there is still no guarantee that you have eliminated layered protein char-stain from your stainless equipment, most particularly in large stainless steel tanks. It has become common practice to rinse with a low dose aqueous citric acid after the caustic cleaning process to neutralize any residual sodium salt and reduce Ca/Mg scale.  This process will not remove the charred biofilm, (as you may well have already experience), and this biofilm is the perfect breeding ground for Brettanomyces to flourish within your tanks. 

In an attempt to fix this ‘filming’ problem where there are heavy stains, rather than re-cleaning equipment with more reliable cleaning products, it has become common practice in some wineries to increase the concentration of the caustic solution and increase ‘cleaning in place’ (CIP) circulation time.  What you need to understand and what we are trying to stress is, simply putting more caustic in and leaving it there for longer won’t remove the bio-film but may in-fact, exacerbate it.  If you increase the concentration of caustic in solution, you run the risk of premature ageing of your assets (e.g. pitting in the stainless surfaces of your tanks), and you increase the danger for your employees having to mix a dangerous good in higher proportions, which can cause severe burns if it comes in contact with skin or eyes.  Caustic is strongly reactive with aluminium and can cause degradation of glass surfaces, so not only do you have to be careful about where and how you store it, but also how you use it. 

So let’s look at some more chemistry.  When a quantity of caustic soda granules (pearl) comes into contact with a small volume of water it creates a strong exothermic reaction which can be dangerous to users as it can cause high pH vapour, which then comes into contact with the skin, or worse, the eyes.  If you are using hot water in your cleaning process (which we would strongly recommend), a much more volatile and dangerous ‘spitting’ reaction occurs upon contact of caustic with water.  The highly alkali pH of caustic solution can lead to blindness if it comes into contact with your eyes.  So the real question is, why risk this happening to your trained cellar staff, or even to yourself if you are the all-in-one person in a small/micro winery?

Yes, caustic is cheap.  However, when a staff member is injured due to using a dangerous good, workplace injury claims aren’t cheap; and wasting wine isn’t cheap when your wine tanks and lines aren’t really satisfactorily and they become infected with unwanted microbes.  It’s simply not worth it.  It’s time to use your grey matter, look across the spectrum and compare the greater negatives with the few positives for commodity caustic soda.  The alternatives now available are far more effective at cleaning your surfaces, safer for you and your wine and require less effort to get the job done correctly the first time - but that’s a conversation for another time.  

If you have any questions about caustic alternatives, then get in touch, because it is time to stop using caustic, it’s time to start cleaning smarter, safer and cleaner.