Ozone: A Noxious but Useful Gas. (Food for Thought)

Article excerpt

Generally, we associate ozone with the stratosphere. If we are exposed to ozone at high levels, it is toxic. Under controlled conditions, however, this gas is useful as an antimicrobial agent with food and water.

The strong oxidizing properties of ozone gas were discovered as early as 1840. Ozone has proved to be capable of killing many micro-organisms that contaminate food and water, and it is more effective than chlorine in its ability to kill a wide variety of virulent pathogens.

Early in the 20th century, France began to use ozone to disinfect drinking water. Soon, many other European countries adopted this practice. Ozone use was extended to protect foods as well, and these practices have continued in many European countries. However, such applications lagged in the United States and have been introduced only recently here.

In poultry processing, the carcasses undergo a water bath. In 1996, the U.S. Department of Agriculture approved the use of ozonated water for the water bath of poultry carcasses. Ozone generators create the ozone readily by sending an electrical discharge across a flow of air or pure oxygen. A compact generator, installed in the food-processing line, creates a continuous flow of ozone into the water. This is necessary because ozone breaks down readily into harmless diatomic oxygen. Ozonating the wash water allows it to be reused. The practice reduces both water use and cost, as well as the time required to decontaminate the carcasses.

In 1997, an independent panel recommended that the Food and Drug Administration recognize ozone as GRAS (Generally Recognized as Safe) for sanitizing bottles used for bottling water, and to sanitize bottled-water plants. Even after this GRAS approval, ozone could not be used on food without approval of a further petition filed with the FDA. Hoping to expand ozone use, the Electric Power Research Institute filed a broad petition to have ozone approved as a food additive. In June 2001, the FDA approved this petition. Ozone, as a gas or dissolved in water, is permitted for use as an antimicrobial agent with foods, including meat and poultry. Also, use of the gas is permitted in reducing microorganism levels in processing raw agricultural commodities. In addition to the FDA, the Environmental Protection Agency regulates ozone under the Federal Insecticide, Fungicide, and Rodenticide Act.

Currently, researchers are exploring the possibility of using ozone to clean the surfaces of food animal carcasses. In experiments with fresh raw meat, ozone levels of 0.04 parts per million controlled and retarded microbial growth. A level of about 0.10 ppm helped age and tenderize beef. Ozone storage of meat that has only a low bacterial count can extend the meat's shelf life by up to 40%.

Dissolved ozone in water used to wash fruits and vegetables protects them. Studies show that ozonated water can reduce the total bacterial count on some vegetables by more than 90%. The treatment also reduces fungal infections and the resulting deterioration from fungal decay. …