Following the decision by the Pabst Brewing Company of Milwaukee to introduce a sterile filtered, unpasteurized beer brand, the problem of maintaining the necessary standard of hygiene on the canning line (which was also to be used for pasteurized brands) gave cause for concern, since the properties of the disinfectants then available (chlorine based, iodine based, quaternary ammonium compounds and acid anionic products) were not well suited to the task in hand. The iodophor chosen as the least unsatisfactory product on the market caused fobbing and off flavours. However, a new product known as "oxonia active", a stabilized equilibrium mixture of peroxyacetic acid and hydrogen peroxide, became available and allowed the problem to be solved. Although the disinfecting efficiency of peroxyacetic acid has long been known, problems with stability and handling difficulties made its use in pure form impractical. The stable form (first developed in 1975 and approved by the US Environmental Protection Agency in 1986) has similar disinfectant properties to chlorine, but does not give off any gases or vapours, nor does it form toxic reaction products in water as chlorine does. It does not foam and is slightly acidic, therefore compatible with the presence of carbon dioxide, while remaining effective over a wide range of temperatures and pH values. Although corrosive to copper and its alloys (brass etc.), oxonia active is less so than chlorine products. At the concentrations applied in beer packaging, unrinsed cans or bottles only carry very low residue levels, which break down to release atomic oxygen which (unlike molecular oxygen dissolved out of the air) immediately and harmlessly reacts with beer enzymes, traces of weak acetic acid below the taste threshold level, and an equally insignificant amount of water. These breakdown products are also harmless to the environment.
Keywords : acid disinfectant efficiency safety