The Essentials of Cleaning
Cleaning is a pretty straight-forward process. Add some soap, scrub and rinse. That’s really all it takes to clean most surfaces. But when it comes to the chemical processes involved in the act, things can get fairly sophisticated. In fact, soil formation is a pretty complicated process, especially when we talk about brewing. That’s when chemistry becomes even more important because the right chemistry can reduce the amount of energy required to complete the cleaning process, and when “energy” means “elbow grease,” you can see how chemistry makes things easier.
Our goal here is to help you understand the soiling that occurs in brewing, how chemistry can be used to remove it and how the right chemistry can make the process environmentally safe and friendly for you, the people who consume what you brew and the community at large.
Let’s talk about what types of soils occur in the process. You know that quality wort or must is critical to your end result, but these consist of a number of substances that change as the boiling and/or fermentation progresses. You’ve probably noticed that some vessels (like mash tuns, presses, or totes) are fairly easy to clean with a water rinse and a sponge or scrub pad, while boiling vessels and fermenters take a lot more effort. The reactions that result in a hot and cold break are partially to blame, but there is also the association and deposition of minerals and macromolecules that must be considered because they are increased by the heat differential between the fluid and the environment of the vessel, whether it’s during a boil or simply during a long fermentation.
Coagulated proteins cling to hard surfaces, such as metal, glass or plastic. Imagine the proteins as being kind of web-like and you can see how they can start to trap minerals, fats or oils. In fact, it is this interaction and trapping can give rise to complex biofilms, which can be very difficult to remove. Another good example of this for brewers is beerstone, in which proteins and carbohydrates form a complex structure with mineral scale.
Think of soil films as painted surfaces, or at least surfaces that are well-painted. The first coat or primer lays the foundation and gives all future coats a surface to which they will adhere. The second coat and each subsequent coat provide more complete coverage and a thicker layer over the painted substrate. Each of these coats make water, sunlight, and all other sources of weathering less effective in getting to the painted or protected surface.
Unfortunately, the same type of action occurs in your boiling kettle, fermenter and other vessels. This coating occurs as solids settle out from your wort or must and, over time, will lay coating after coating over the surface. It gets worse with a greater temperature difference between the two sides of the surface like, for instance, if you are cooling a fermentation vessel. The bottom line is that soil builds up and if it is not removed completely each time your equipment is used, it will just get harder and harder to remove.
Choosing a Cleanser
Clearly there is a lot going on when you use chemistry to clean your equipment, but not all cleansers are created equal. The simplest way to determine if the cleanser you are using is helpful is to try multiple products and brands, but there are easier ways. If the cleanser lists the ingredients, look at the label.
Most quality cleansers will incorporate silicates and phosphates that are very helpful, although you may choose not to use a phosphated product. (The problem with phosphates and some other chemicals are discussed below.) Soda ash is generally a large component because it contributes alkalinity and serves as a good “filler.” (“Filler” in the cleansing industry is a substance that allows users to measure out a tablespoon of a reasonably priced product at a time rather than using an eighth of a teaspoon of a very expensive product. Soda ash is called filler because it is inexpensive, not because it is ineffective.
You may also see polyacrylates and surfactants on the label, although they are generally in such small quantities that the manufacturer will not bother to add those to the label.
Finally, you may see a chemical with either “oxygen” or “per” as part of its name, which means that you are getting a product that incorporates oxygen bleach into the system. This can be very helpful, but it will also increase the expense.
(Personal Note: This is an expense that I believe is worthwhile in my own brewhouse.)
Environmental Considerations in Cleaning
Phosphates used in cleaning compounds tend to have a bad name in environmental circles because they are excellent micronutrients. Too much phosphate can cause algae blooms that will suck the oxygen out of water bodies. “Greening” waterways became a problem of great public concern in the 1970’s and ‘80’s and resulted in heavy-handed phosphate bans. The problem, though, is that phosphates have a singular role to play in cleaning operations and industry was forced to devise new compounds to take their place.
Unfortunately, some of the replacements for phosphates are no better and are sometimes worse. Ethylenediamine Tetraacetatic Acid (EDTA) works very well in handling the mineral component of soils, but it also plays a large role in mobilizing heavy metals. In other words, the biggest problem with EDTA (to date) is that when it finds its way into nature, it will help heavy metals such as mercury to move into active water rather than remaining undisturbed. Other compounds, such as Nitrilotriacetate (NTA) are very effective but are suspected carcinogens and are banned in some states.
Despite the black eye that phosphates received, they remain one of the best components to use in cleaning. In critical cleaning operations, such as healthcare, phosphates are often exempt from the same regulations they face in other areas of use. The bottom line is that phosphates should not be dismissed out of hand if they are present in a quality cleanser. Having said that, we do not use phosphates in our products form home users because we sell our products across the U.S. and in other countries. We cannot anticipate the issues that are facing a particular region and do not wish to contribute to a problem if we can easily avoid it.
Generally speaking, powdered cleansers tend to break down easily into naturally occurring components over time. In fact, breweries have a much harder time in dealing with the actual waste streams from their brewing than with the waste streams from cleaning.
If your concern is minimizing the environmental impact, which is certainly admirable, avoiding the compounds mentioned above — NTA, EDTA, and phosphates – is a reasonable first step. Using a cleanser with oxygen present would be helpful because that will encourage aerobic organisms to digest the discharged soil and cleaning solution. As a side note, these types of cleansers will have negligible impact on septic systems simply because of the sheer volume of waste typically in a tank and drainage field.