Barrel Sanitation with Ozone

It's important to understand that barrel sanitation using ozone is not the same as barrel sterilization. The surface of barrels do not have a discrete surface, it is more like a 4-5mm sponge, often with blisters. The porosity of the barrels provide far too many nooks and crannies for ozone in any concentration and duration to completely eradicate all microbes. The ozone treatment of barrels is designed not to eliminate microbes, but instead to control them. This concept of microbial control is especially important when ozone is used to treat barrels with high populations of microbes, which can produce off-flavors or cause wine spoilage.

Many wineries have implemented ozone as a part of their barrel-washing practices. Standard procedure for barrel washing varies from winery to winery, but it typically includes a high pressure, hot water rinse, followed by a dissolved ozone water treatment. The concentration of ozone applied, as well as the contact reaction time in the barrels, depends on the quantity and nature of the contaminant. Larger quantities of microbes in contaminated barrels require longer treatments, but smaller doses may be required to handle sensitive materials. Typically, a 2.5 ppm ozone concentration for two minutes on healthy barrels, after a hot water flush, is sufficient. If the barrel is severely contaminated, a five-minute treatment may be required.

Bacteria Inactivation by Ozone
    E. Coli 0.02-0.06 mg-min/L=CT (2-log) AWWA
    Streptococcus faecalis 0.01-0.025 mg/min/L=CT (2-log) AWWA
    Legionella pneumophila 0.3-1.1 mg-min/L=CT (2-log) AWWA
    Total Coliform 0.19 mg-min/L=CT(6-log) LAAFP
    HPC 0.19 mg-min/L=CT (3-log) LAAFP


Benefits of Using Ozone

    Ozone offers higher sanitization quality, time, and energy savings.
    Decreased chemical use by using natural ozone gas, which is produced safely.
    Economical through sophisticated, yet easy-to-use integration.
    Ozone generation and contact systems are the world's most powerful cleaning process.
    Commercially available disinfectant. Ozone kills microbes up to 5000 times faster than weaker oxidizers like chlorine, but it decomposes naturally into oxygen unlike harsher agents with harmful disinfection by-products

Clean In Place (CIP) of Piping

Diagram of an example Ozone CIP System.

The biggest threat to winemaking is contamination during the long production process from harvest to tank to barrel to final bottling. Clean-in-Place (CIP) involves cleaning and sanitizing pump systems, pipes, tanks, hoses, filters, and bottling lines. Using ozone in the CIP process saves time as well as costs. Dissolved ozone water is circulated through the piping systems and reacts with organic material.

Many modern ozone generators have controls built-in which receive signals from ozone sensors connected to the pipes or tanks. This allows machinery to be cleaned and sanitized easily and automatically.

Without ozone, CIP sanitation must be done by one of two ways. The first is by using chemicals, typically chlorine or iodine solutions, requiring multiple rinses afterwards to remove noxious residues. The other option is by using heat, usually high temperature water or steam, which is very expensive to produce and creates a danger for cellar employees. In contrast, ozone achieves CIP sanitation at low cost, at ambient cellar temperatures, and without harsh chemical residues. Furthermore, hot water or steam causes the expansion and contraction of welds, one of the biggest causes of line degradation and repair. Heat can also bake on materials inside the lines, making them more difficult to clean. Since ozone is used in cold water, it avoids these and other issues caused by heat based CIP sanitation.