Sanitizing agents, also known as disinfectants, are used in brewing to reduce the number of microorganisms to acceptable levels. Sanitization can be achieved through physical methods or the use of chemical sanitizers. Physical methods include using hot water or steam to kill bacteria. Chemical sanitizing involves immersing the object in a sanitizing solution for a specific amount of time or spraying/wiping the object with the solution and allowing it to air-dry. Chemical sanitizers vary in effectiveness against different microorganisms and require specific concentrations, temperatures, and contact times to kill bacteria. Common chemical sanitizers used in brewing include chlorine compounds, quaternary ammonium compounds, hydrogen peroxide, peroxyacetic acid, anionic acids, and iodophores.
Some brewers prefer steam or hot water for brewery sanitation because they believe chemical sanitizers can affect the beer’s taste with unpleasant odors. To be effective, steam must be wet (not superheated) and free from air.
Physical versus Chemical Sanitation
The advantage of physical sanitation is the elimination of chemical sanitizing agents. However, its application is limited due to the energy required to produce steam or hot water, and it may not be suitable or effective for all applications. Chemical sanitation is predominantly used in the beer brewing industry.
Chlorine-based sanitizers are widely used in the beer brewing industry. Chlorine compounds are broad-spectrum germicides that act on microbial membranes, inhibit enzymes involved in glucose metabolism, have a lethal effect on DNA, and oxidize cellular protein. Chlorine is effective at low temperatures, relatively inexpensive, and leaves minimal residue or film on surfaces. Properly blended chlorine-based sanitizers are relatively non-toxic, colorless, non-staining, and easy to prepare and apply.
Quaternary ammonium compounds, commonly known as “quats” or “QACs,” are extensively used in breweries due to their stability and non-corrosiveness. They have rapid bactericidal action at very low concentrations but selective biocidal activity. QACs are efficient against gram-positive bacteria but less effective against gram-negative bacteria. They also have high effectiveness against yeast and mold.
Hydrogen peroxide (HP) has a broad spectrum of activity, with slightly higher effectiveness against gram-negative organisms than gram-positive organisms.
Peroxyacetic Acid (PAA)
Peroxyacetic acid (peracetic acid, PAA) has long been recognized for its germicidal properties. One advantage of PAA is that it doesn’t produce vapor issues like chlorine-based compounds when dosed into water. Other advantages include the absence of phosphates and foam, as well as its biodegradability. PAA remains relatively stable at use strengths of 100 to 200 mg/l.
Anionic acids are rapidly growing in popularity as sanitizers in the craft brewing industry. They are chemicals composed of two functional groups – a lipophilic portion and a hydrophilic portion – resulting in a negative charge. The negatively charged anionic acid sanitizers react with positively charged bacteria through attraction of opposite charges.
Iodophores have a wide spectrum of biocidal activity and directly react with cells. They are not affected by resistant species of yeast, bacteria, or molds. Iodophores are iodine-containing formulations usually consisting of elemental iodine, a surfactant, and an acid such as phosphoric acid. The surfactant reduces the staining and corrosive properties of iodine, making it a more effective sanitizer than chlorine at comparable concentrations.