Ozone is a molecule that is made up of three oxygen molecules (O3) that exists as a pale blue gas. It is much less stable than the allotrope of oxygen that exists in our atmosphere (O2). It is slightly soluble in water, but it is very soluble in inert non-polar solvents where it then forms a blue liquid solution. Ozone in the air and in solutions is generally kept at low concentrations because humans can detect it and are affected by it at low levels. At around .01 ppm of ozone in the air, people are able to detect a sharp odor similar to that of bleach. Exposure of 0.1 to 1 ppm produces headaches, burning eyes, and irritation to the respiratory passages. The largest use of ozone is in the preparation of pharmaceuticals, lubricants, and many other useful organic compounds where its properties can be used to break up carbon-carbon bonds. Ozone can also be used for bleaching substances and for killing microorganisms in air and water sources, which is why it is used in wineries. Ozone must be generated on site.
Ozone is being used more and more often as a sterilization tool in wineries because of a number of unique properties that it has. Ozone can't be stored on-site, instead being generated for use as needed. This is beneficial because no accommodations have to be made to contain the compound and possible risks that come with storage are avoided. Ozone is powerful enough that microbes can’t develop a tolerance to it, maximizing its effectiveness. It is also known to be environmentally friendly when used correctly. Because ozone is an unstable compound, it reverts back to oxygen before entering settling ponds, causing no damage. It also doesn’t leave any residual compounds or chemical bi-products that could affect future production in the winery.
Application in Wine Microbiology:
Ozone is used for bleaching substances and for killing microorganisms in air and water sources, which is why it is used in wineries. It is created on-site and then placed into a solution made with cold water. This makes it much more cost-effective than hot water rinses, saving heating costs and cutting out time to warm up and then cool down the water. It can then be applied to equipment in the winery either through a CIP (Clean in Place) mechanism or through mobile wash carts. It is more common for wineries to use mobile wash carts, as they allow a greater variety of surfaces to be reached. The ozone containing solution is then applied to the equipment as a spray wash. Upon making contact with the winery equipment, the solution then is able to sanitize the surfaces that it comes in contact with. The solution has been proven to be effective against the following types of microorganisms: fungi (yeast, mold and spores), protozoa, bio-film, bacteria, and viruses. The microbes that the ozone treatment is known to be especially effective against are Acetobacter species of bacteria and Brettanomycesspecies of yeast.
Ozone treatments have become increasingly popular, having been proven to be a logical choice for sanitization in wineries due to a number of factors. With the compounds being generated on-site, transportation and handling issues are minimized. It has been shown to generate minimal amounts of risk to product taste. It also reduces costs, lowering chemical-related costs and wear on equipment. Over the last twenty or so years, ozone treatments have been being used with positive results, partially due to the fact that it is considered a natural sanitizer for a natural product.
- Hampson, Brian. “Use of ozone for winery and environmental sanitation”. Practical Winery and Vineyard. January/February 2000. http://www.practicalwinery.com/janfeb00/ozone.htm