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Sanitation Techniques

In the September 2016 column I discussed cleaning techniques in the brewery, so now we must look at sanitizing brewing equipment, since that comes after cleaning. That’s a very important statement in this context, because you can’t sanitize dirty vessels and utensils. If you try it you will only sanitize the dirt, not what is underneath it. And if what’s underneath it is bacteria and/or wild yeasts you are in trouble, for these beasts are survivors and very clever at getting under protective cover and staying there until a suitable food source comes along. And if that food source should happen to be the wort you have carefully and expensively prepared for them you may well have ruined your beer before it has even finished brewing.

A potentially spoiling population of bacteria can grow very rapidly as it can double in size in as little as 15 minutes, then double again in the next 15, and so on, depending upon the conditions and the type of bacteria. Since beer, and especially wort, are excellent nutrient media for both bacteria and wild yeasts, you want to minimize any contact of these nasties with your wort. Note that by wild yeasts I mean any yeast other than your designated brewing yeast. Even if you are making a sour beer your wort should be as free of organisms as possible other than the pitching yeast. Souring agents such as Lactobacilli, lactic acid, or Brettanomyces should be added after the brewing yeast has done its work. If all this talk of bacteria and infections makes you worry about the health risks you might be taking in drinking beer, you need not be concerned. Pathogenic organisms just don’t live long in the relatively acidic conditions that beer offers. So, bacterial infections in beer will not make you sick, they will just ruin its taste and your palate!

So, the first rule is that your equipment must be clean before you sanitize it. That brings us to the question, “Why do I say sanitize and not sterilize?” Well, sterile means that there are absolutely NO living organisms present. It is extremely difficult to establish an environment that is completely sterile, involving isolated rooms with airlock doors, filtered air supply, all personnel wearing one-use clothing, and spraying with powerful chemicals, and constant control through swabbing and plating to check the absence of organisms. This is obviously a little more complicated and expensive to set up than is practical for homebrewing. As a matter of fact, most hospital operating rooms are sanitized and not sterile in the rigid sense, even though individual items such as surgical instruments are sterilized in an autoclave.

That may make it sound as though sanitizing is a much inferior approach to sterilizing, but in fact it means that it is as close as you can get to achieving sterility as is practical in most cases, including brewing (in the food and beverage business this is called “commercially sterile”). So what does “sanitized” mean? Well, as far as I can see from the literature there is no absolute and simple definition, although you may see numbers quoted like “more than 99.99% of organisms have been killed.” And right now I am looking at a bottle of a well-known brand of bleach that claims on the label “Kills 99.9% of bacteria and viruses found in the home.” In other words, good sanitizing will get your equipment as close to sterile as is practically possible. There may be some organisms left on your equipment after sanitizing it, but there will be very, very few of them, and they can easily be overcome by a healthy brewing yeast sample. This is one reason why it is very important to make sure that you pitch a sufficient amount of active yeast in your wort. If there are any evil organisms left you do not want to under pitch, because that results in a long lag time before fermentation during which such organisms can grow and cause damage to your beer.

How to sanitize?

Firstly, you have to sanitize all equipment that comes into contact with wort and beer. That means not just fermentation vessels, but also wort chillers, pumps, transfer lines, racking lines, kegs, bottles, even hydrometers, thermometers, and anything else you can think of. Basically

you have to use a chemical that will destroy living organisms, and there are a number of these available. There are several different types, those based on chlorine, those on peroxides, those on iodine, those based on acid plus an anionic detergent.

Let’s look at the chlorine-based first, which means bleach, a dilute solution of sodium hypochlorite. Bleach used to be used very widely by both craft and homebrewers, and is effective in sanitizing brewing equipment as the quote in the earlier paragraph indicates. Typical concentrations for sanitizing are about 1⁄2 cup regular bleach per gallon (4 L) of water. Make sure the bleach is not scented of course, and after a few minutes of contact drain it off and rinse the vessel with hot clean water. Rinsing is a must for stainless steel equipment, because contact with acids used for cleaning can liberate chlorine, which will readily attack and pit the surface of stainless steel.

Acid/anionic detergent mixes are available to homebrewers, a common one being Star San from Five Star Chemicals This is a mixture of phosphoric acid and dodecylbenzenesulfonic acid and is self-foaming, which enables the chemical to penetrate any nooks and crannies that may otherwise be difficult to access. It is recommended that it be diluted at the rate of 1 oz. per 5 gallons (19 L) of water for normal use. After a few minutes of contact time at this concentration the vessel can be allowed to drain dry and need not be rinsed with water. Five Star has another acid/anionic sanitizer — Saniclean — that is low-foaming and might therefore be used to advantage when, for example, you want to pump the solution through some fixed piece of equipment such as a counterflow wort chiller.

In fact, the trend in brewing is towards using no-rinse sanitizers. In part that might be a question of convenience in a busy craft brewery, but it also eliminates the risk of adding back contaminant organisms that might be present in the rinsing water. But this raises the question as to whether any residual chemicals from the sanitizer might be injurious to the drinker’s health or even to beer flavor. In reality, the products sold for brewery sanitation are invariably made from approved food-grade chemicals and should be used at the very low concentrations recommended by the supplier so that only miniscule residues would be expected to remain on the equipment surfaces.

Two other popular forms of sanitizers in brewing are Peracetic acid and iodine. You may be aware that many craft brewers favor Peracetic acid nowadays, which is reduced to acetic acid after it has oxidized any residues. I have not seen this product offered by any homebrew suppliers and I do not recommend its use in homebrewing as it is somewhat corrosive. Peracetic acid does not attack stainless steel but it is capable of corroding other metals and alloys such as copper, brass, bronze, and mild steel. Iodine is much safer to handle and is just as effective a sanitizer at least for our purposes and is used by many homebrewers. Note that other oxidizing agents such as percarbonates do have an antibacterial effect, and as such can be used as sanitizing agents. However, they are usually alkaline formulations and require water rinsing after use; they are most effective for their intended use as cleaning agents rather than as sanitizers.

Iodine has limited water solubility, as is exemplified by “tincture of iodine,” which is an alcohol solution and the form used in the starch-iodine test to determine whether mashing has gone to completion. In sanitizing, it is used as an iodophor, a water solution of a complex of iodine with a solubilizing agent or carrier. The most common form is that of povidone-iodine, which is a compound of polyvinylpyrrolidone with iodine. At the concentrations supplied (around 1–5% iodine) the iodine is not fully available and best sanitizing effects are obtained when it is diluted to a level of 25–50 ppm available iodine, which typically means adding 1–2 oz. of iodophor to 5 gallons (19 L) of water. My point is that in this case more is definitely not better as dilute solutions are more effective in killing bacteria. So you should read the instructions carefully and ensure that your sanitizing solution is used at the correct dilution.

You should allow at least 1–5 minutes contact time (longer times are fine) and then allow the equipment to dry before use; water rinsing is not required. Any residues left behind are minimal in amount and harmless to both beer and drinker. By itself the diluted iodophor solution will be at around pH 2 and is most effective under acidic conditions (pH 2–5). It is ineffective under alkaline conditions, so if you have used any alkaline cleaner, such as bleach or carbonate peroxide formulations, make sure that the vessel or other equipment has been thoroughly rinsed with water before adding the iodophor solution.

Iodophor solutions are not corrosive as such and are perfectly safe to use on metals, including copper, and have in fact been used as antiseptics on cuts and bruises. However, that is no reason to be cavalier about handling them particularly as iodine is toxic to humans when ingested. As with other chemicals they should not be left lying around after use, in fact they will degrade over a couple of days so they should be used only once and discarded. Some homebrewers dislike using these products since they will stain plastic containers an unsightly yellow color. But they are very effective as bactericides, although perhaps slightly less effective than peracetic acid at destroying mold and bacterial spores. Properly and thoroughly used iodophors will ensure that your beer does not suffer from unwanted infections.

Sanitizing workflow

My own approach is to fill the wort receiver and the fermenter, and to soak the immersion chiller, the transfer/siphon tube, and the oxygen diffuser stone all with an appropriately diluted sanitation solution while boiling the wort. When the boil is finished everything is sanitized and ready for transfer of the wort to the fermenter. When kegging I fill the keg with sanitation solution along with the racking tube, as well as soaking the keg lid and inlet and outlet tubes in a similar solution. Obviously, when bottling I also soak the racking arm and fill the bottles with the sanitizing solution and allow them to soak for 30 minutes or more before filling the bottles with beer.

In Conclusion

Cleaning and sanitizing may appear to be boring subjects to read about but if you don’t pay attention to them you will regret it sooner or later. Not only is it heart-breaking to pour away an infected brew it is also very hard work to ensure that you get the equipment thoroughly cleaned of the infecting organism for the next brew! And do remember to clean and sanitize every piece of equipment, not just the main vessels. No-rinse sanitizers are the way to go; if you are not sure about that and still want to rinse with water, be very sure that you are using water with a low bacterial count. Finally, and I cannot emphasize it enough, make sure that you pitch the cooled wort with a sufficient amount of active yeast so that fermentation gets under way before any bugs you might have missed have a chance to multiply!

Issue: October 2016