Food safety is a growing concern worldwide. The CDC (Center for Disease Control and Prevention) estimates that each year one (1) in six (6) Americans get sick from food borne diseases.
In food processing it is important to provide pathogen free food products. Keeping food products pathogen free and reducing the potential for cross-contamination of potentially deadly pathogens is very crucial, and that is why surface sanitation is so important. This page will provide some detail on the potential use of ozone for surface sanitation.
Many processing plants already use ozone-in-water, or aqueous ozone for antimicrobial intervention steps directly on the surface of food products. Due to the FDA and USDA giving ozone GRAS (Generally Recognized as Safe) approval for use directly on the surface of all food products the use of ozone has spread dramatically in the last 10 years. Ozone use for surface sanitation is just one more cost saving method that can be implemented by plants already using ozone, or for plants that would like lower cost and have a more effective method for surface sanitation.
One of the major concerns for cross-contamination on food processing equipment is bio-film buildup. Bio-films are layers of microorganisms bonded tightly to a surface. Microbes can attach themselves to a surface and continue to grow layer upon layer of new microbes. The new layer of microbes can provide nutrients and protection against sanitizers to the existing layers of microbes. These layers of microbes can continue to grow, and become more resistant to sanitizers over time making sanitation more difficult if proper sanitation is not achieved on a regular basis. These resistant bio-films are most common in cracks, crevices, and corners of food processing equipment that are only sanitized periodically.
CDC estimates that each year roughly 1 in 6 Americans (or 48 million people) gets sick, 128,000 are hospitalized, and 3,000 die of foodborne diseases. http://www.cdc.gov/foodborneburden/2011-foodborne-estimates.html
A common sanitizer in the food processing industry is chlorine. Chlorine is mixed with water providing chlorinated water to be used as a sanitizer. Some microorganisms such as E.coli and Giardia can build resistance to chlorine over time. This may make chlorine less effective than desired over time. Chlorine residual in waste water can also be regulated and make water recirculation or discharge more difficult due to chlorine residuals in the water.
One more drawback to chlorine and other chemicals is the harsh effect they may have on equipment made of metals and wood. Common issues are steel components that chlorinated water is constantly exposed to, shortening the life of potentially expensive equipment. Wooden wine barrels are also damaged by harsh chemicals. Winemakers take special care to choose high quality wooden barrels to age wine within, this wood can be damaged or altered to the point it no longer serves the original purpose.
Ozone can be dissolved into water just as chlorine and other chemicals can be. In many plants ozone injection systems that provided aqueous ozone may already be in place for use on food products for anti-microbial intervention. Aqueous ozone can be sprayed anyway within the plant safely. Equipment, walls, floors, drains, tanks, tubs, racks, knives, and tables can all be sprayed with aqueous ozone. Enclosed piping can also be sanitized with ozone using a Clean in Place (CIP) system.
During sanitation with ozone a two-step process is generally required. Surfaces are cleaned and bio-films are removed with a hot water or cleaning step. Then aqueous ozone is used to sanitize the surface destroying all bacteria, viruses, fungi, and spores. No other sanitation step after the use of ozone is necessary. In fact no rinse step is necessary after ozone as the ozone will leave no residual on the surface. This may lower cleaning time and water usage costs.
Ozone is a powerful sanitizer that leaves no residual on the surface of equipment or materials. This limits the corrosive potential of ozone and provides a more gentle sanitizer than many of the common chemicals used. Ozone will provide great sanitation results without the harmful effects on metal or wood equipment.
Ozone can be used throughout the day during processing. As there is no danger in damaging product with harsh chemicals, ozone can be used to sanitize processing equipment throughout the day during normal processing. This may lower down time, and allow for more production hours.
Tests conducted in 1999 by California Polytechnic State University at a pilot plant showed the effectiveness of ozone in reducing microbiological loading. The Ozone System in use provided a 2.0 ppm dissolved ozone level that was sprayed on the surfaces to be sanitized. No other cleaning methods were used with the ozone to ensure all reductions in bacteria were attributed to the aqueous ozone. The table below shows the results from this test.
|Effectiveness of Ozone|
|Surface||% Reduction in Plate Count|
|Stainless Steel Kettle||89.7-98.2|
|Stainless Steel Tabletop||98.9-99.7|
|Floor Drain 2nd Attempt||77.5|
|Plastic Shipping Containers||96.9-97.2|
Ref: Use of ozone for winery and environmental sanitation
By Brian Hampson, PhD, Food Science and Nutrition Dept
California Polytechnic State University, San Luis Obispo, CA
Tests were performed at a Fortune 50 Pork Processing Company to determine the effectiveness of aqueous ozone for sanitation of hard surfaces, meat cuts, and knife dips. These tests were performed in a working plant in normal working environments. Samples were sprayed with aqueous ozone ranging from 1.1 - 1.4 ppm for about 10-15 seconds. All tests compared microbiological counts on samples before and after ozone, ozone vs 180-deg F water, and ozone vs 180-deg F water and cold water.
In these tests, ozone performed very well as a sanitizer. Ozone showed a consistent reduction in microbial loading on each material tested. In all tests ozone performed at an acceptable level for sanitation. In many tests ozone outperformed 180-deg F water. As these tests were performed in real world environments with fairly conservative ozone levels (1.1 - 1.4 ppm) these results are very realistic and show the potential for ozone use as a surface sanitizer.
Results from tests at a Fortune Fifty Pork Processing Plant 4/09/02. The Effectiveness of Ozonated Water for Hard Surface Sanitation, Meat Cuts and Knife Dips-Microbial Kill Results http://www.ozonesafefood.com/Ozone_Report_1.pdf
Decontamination of a Multilaminated Aseptic Food Packaging Material and Stainless Steel by Ozone
Authors: Mohammed A. Khadre, Ahmed E. Yousef
A multilaminated aseptic food packaging material. . . .
Click here for the abstract
Studies on the disenfection and removal of biofilms by ozone water using an artificial microbial biofilm system http://www.tandfonline.com/doi/abs/10.1080/01919510802586566
Ozone can also be used in the gaseous form to disinfect and sanitize areas. While actual bio-films will not be removed with gaseous ozone, there are applications where this may be a suitable solution. Many applications do not allow for water to penetrate locations where bacteria may reside and cause future cross-contamination. Gaseous ozone has been used for many years for odor control, mold remediation, and other disaster restoration services. The same action used to remove odor and mold spores can be used to kill bacteria and mold in industrial settings.
The use of gaseous ozone has been tested in various forms for many applications. A wide variety of applications from hospital rooms to sports gear, such as hockey equipment, have used gaseous ozone for disinfection. When using aqueous ozone for surface sanitation the two main variables that affect the success of ozone are contact time and ozone levels. When using gaseous ozone a new variable, humidity, will dramatically affect the results. The level of humidity in the environment will affect the ability of ozone to penetrate and destroy microorganisms. The following research will show a new variable affecting the results of microbiological reduction with ozone.
This study investigated the potential of gaseous ozone to inhibit growth of microorganisms on surfaces. This study evaluated the effectiveness of ozone at varying ozone concentrations, for various contact times, at varying relative humidity.
The effect of ozone on Apergillus niger, Pseudomonas aeruginosa, and a mix of microorganisms was tested. Highly contaminated surfaces were exposed to ozone gas at various levels ranging from 0.1 to 5,000 ppm in these tests. Exposure times from 20 minutes to 120 minutes were used at low ozone levels, while exposure times of 0.33 minutes to 20 minutes were used at 5,000 ppm. Humidity showed a great affect on the reduction of bacteria in the presence of ozone gas. Altering the humidity level from 15-25% to 85-95% showed a greater change in bacterial reduction than altering the ozone level in some tests.
Inactivation by gaseous ozone of different types of microorganisms is successfully achieved provided, as is well known, the gaseous phase is strongly humidified. The inactivation mechanisms and species involved in this process are, however, not yet clearly identified. To gain insight, we considered exposure of bacterial spores to dry rather than humidified ozone, a less complex chemical environment. In contrast to most of the published literature, it is shown that, under strict dry ozone conditions, bacterial spores can be inactivated, but to a degree that is largely dependent on the spore type and substrate material. In this case, the O3 molecule is determined to be responsible for the inactivation process through its diffusion into and oxidative action within the spore, as no outer erosion of the spore is detected. With humidified ozone, a higher inactivation efficiency is observed that is most probably related, in part, to the swelling of the spore, which facilitates the diffusion of oxidative species within it and up to the core; besides O3, these oxidative agents stem from the interaction of O3 with H2O, which in the end leads to a heavily damaged spore structure, in contrast to dry-ozone exposure where the spore integrity is maintained.
This project evaluated the effects of exposing a variety of microorganisms on porous and non-porous materials to elevated gaseous ozone concentrations ranging from 100 - 1000 ppm. Gypsum wallboard (porous) and glass slide (non-porous) building materials were used. Two fungi organisms, two bacteria organisms and two levels of relative humidity (RH) were tested. Increased humidity and non-porous surface exposure were found to increase the biocidal capability of high levels of ozone. The results of this study indicate that even at relatively high concentrations of ozone, it is difficult to get significant reductions of microorganisms on surfaces, especially on porous materials.
We evaluated the ability of a portable ozone generating machine (Viroforce 1000) to inactivate 13 different species of environmental fungi. Samples, prepared as wet or dried films, were subjected to one or two cycles of treatment (35 ppm ozone for 20 minutes, with a short burst of ±>90 ± relative humidity), and measured for residual viability. Treatments could inactivate 3 log10 cfu (colony forming units) of most of the fungi, both in the laboratory and in simulated field conditions, on various surfaces. We conclude that the ozone generator would be a valuable decontamination tool for mold removal in buildings.
Ozone has a bright future in surface sanitation. The use of ozone for surface sanitation in process using aqueous ozone, CIP, and gaseous ozone will continue to grow. If you have an application that you would like to evaluate the potential of ozone, give us a call. We would be glad to discuss your application and provide the technical support necessary to implement ozone as a solution.
Last Updated: July 31, 2014