Caustic does not clean.  And it definitely doesn't sanitise.
That brown tinge in your bottling tanks or throughout your bottling line could be causing you more problems than you think.  It is a signal, and a very important one, that your line isn’t clean.  Of most concern is that if it isn’t clean in areas you can see, just think about all the areas in the line that you can’t see.
The brownish tinge is often a bio-film and is putting each wine moving through your bottling hall at risk.   This risk can be completely eliminated through good hygiene practices.  The first step is to understand the nature of wine arriving at the bottling hall and the reactions that high pH products can have in bottling lines.
Finished wine that is about to be bottled is different to that in the cellar.  These wines don’t contain heavy tartrates or high soil loads.  The lighter tartrate and organic soil loading means less reliance on pH to remove wine films and surface staining.  There is a tendency though, in bottling halls, to reach for high pH commodities such as sodium or potassium hydroxide (caustic) and this is where the trouble starts.
There are myths about caustic products.  The most common one is that sodium or potassium hydroxide will sanitise.  This is not the case.  A recent study of comparative sanitising agents found that sodium hydroxide (NaOH) didn’t meet the same standards of proven sanitisers such as peroxy-acids (Abban et al, 2013).  The alkaline environment does provide a small amount of resistance to microbes, yeast and bacteria, however caustic doesn’t meet the standards necessary for a surface to be deemed sanitised.
We’ve spoken about caustic products previously (read more here) and the issues that high pH products cause.  There is no doubt that inadequate cleaning through the use of commodity caustic leads to protein char (or protein staining).  This protein char is a biofilm and can put your wine in danger right before it enters the bottle.
“…biofilm formation in the winery is clearly undesirable as it can become a serious source of contamination.” (Joseph et al, 2007).

Biofilms are all around us (for example plaque on our teeth).  When bacteria aggregate on a surface they form an extracellular glue-like matrix that protects them and attaches them irreversibly to that surface.  At this point the resultant community is referred to as a bio-film (Joseph et al, 2007).  The issue continues because micro-organisms living in biofilms are much more resistant to disinfectants (Vlkova et al, 2008).   The really dire news is that once a biofilm has formed on the surface it is much harder to remove - you’ll need more chemical, more washes, more manual action and more time.  Just more of everything to remove it.
“Biofilms are formed by different species of micro-organism are dangerous because they protect one another during the application of chemical agents (for example alkaline chlorine solutions).” (Vlkova et al, 2008)
There are more risks to high pH.  Chemical manufacturers often use Sodium Metasilicate or Disodium Metasilicate to eliminate foam.  At a high pH it is difficult to disperse foam in a cost effective manner.  A cheap way of doing this is to use silicates.  This is an issue as silicates compound layers over time to form a chemical film.  This chemical film enables another environment where microbes, yeast and bacteria can persist.  This effectively is stinging bottling mangers twice,firstly they have a biofilm from the caustic and secondly it is much more difficult to remove because of the silicates.
So there are some issues with caustic.  Most bottling managers will state that a steam or hot water sterilisation will resolve this.  On first glance this seems reasonable, anything not caught by the caustic will be eliminated through hot water or steam sterilisation.  Easy right?
Well no, not really.  It is extremely difficult to sterilise every part of the bottling line - from filler tanks to fittings.  Some parts of the line, which may be hard to reach are simply not reaching the required temperature to create a sterile environment.  This gap is then compounded by potential biofilms or chemical films protecting microbes, yeast and bacteria in the bottling hall.
“Proper cleaning enhances the effectiveness of the sanitation process.  Cleaning removes the soils and enables a surface to be sanitised.” (Bar-Am et al, 2012).
The good news is that there are several steps bottling halls can take to eliminate their risk.  The first is stop using caustic.  Find a mid pH alkaline cleaning agent which will help wash off any light films that are produced.  Make sure that the chemical does not contain any sodium metasilicate or disodium metasilicate.  In our range we would suggest Destainex LF, Cleanskin or Citsanex.
In Australia and New Zealand, bottling organisations should also use a chemical sanitiser (in our range Linvasan, PerCitra or Vinisan) as a second precautionary step prior to a steam or hot water sterilisation.  In the USA and Canada, Destainex LF will provide an excellent clean surface and will reduce the microbe, yeast and bacteria count significantly (through oxidation).  This way you’ll be sure that your process is robust and no-hard to reach areas are going to put your wine at risk.
The benefits of moving away from caustic are immense.  Not only will your bottling hall be safer and cleaner, but you’ll also reduce the amount of salt going into your waste water stream and you’ll be giving your wines far better protection.

Abban, Jakobsen and Jespersen, A practical evaluation of detergent and disinfectant solutions on cargo container surfaces for bacteria inactivation efficacy and effect on material corrosion, 2013, Department of Food Science, University of Copenhagen, DK -1958 Frederiksberg C,Denmark Accepted 5 June, African Journal of Biotechnology Vol.12(23) , pp. 3689-3698
Calanit Bar-Am, Jim Lapsley, Rolf A.E. Mueller and Daniel A. Sumner, Grapevines of Innovation: Ozone as a Cleaning Agent in the California Wine Industry, Journal of Wine Economics, Volume 7, Issue 01, May 2012, pp 108-125

Filomena L. Duarte, Alberto López, M. Filomena Alemão, Rodrigo Santos, Sara Canas, 2011, COMMERCIAL SANITIZERS EFFICACY – A WINERY TRIAL pg 45-52, Instituto Nacional de Recursos Biológicos

Biofilms and Hygiene on Dairy Farms and in the Dairy Industry: Sanitation Chemical Products and their Effectiveness on Biofilms – a Review.,Czech J. Food Sci. ,26: 309–323

L. Joseph, G. Kumar, E. Su, and L. Bisson, 2007, Adhesion and biofilm production by wine isolates of Brettanomyces bruxellensis, In: American Journal of Enology and Viticulture 58(3):373-378.2007