Use of ozone in sanitation and storage of fresh fruits and vegetables

Background: keeping fresh produce safe after harvest

Fresh and fresh-cut fruit and vegetables spoil quickly and can carry microbial contamination as they move from harvest through storage to sale. Growers and processors have traditionally relied on chlorine and other chemical washes to reduce this load, but these can leave residues and unwanted by-products. Ozone, a naturally unstable form of oxygen, is a powerful oxidant that breaks back down into oxygen and leaves no chemical residue, which has made it an attractive candidate for cleaning produce and for treating storage air and process water.

What this review covers

This narrative review draws together published work on the use of ozone - both as a gas and dissolved in water - across the postharvest chain for fruit and vegetables. The authors summarise how ozone is applied to surface decontamination, storage-room air, and wash and recycling water, and they weigh its effects on microbes against the practical and economic constraints of using it at industrial scale.

Findings reported across the studies reviewed

The review reports that ozone acts as a more efficient biocide than many conventional chemical agents because of its high reactivity and strong oxidising power. Across the cited studies, ozone treatment reduced microbial spoilage and weight loss in apples, cut mould and bacterial counts on onions without altering their chemical composition, and preserved quality attributes in tomatoes while lowering microbial populations. The authors note that outcomes depend heavily on dose, exposure time, temperature, humidity and the specific commodity, and that ozone can damage some produce if the treatment is too strong.

What the authors concluded

The authors conclude that ozone is a promising, residue-free alternative to chemical decontamination for fresh and fresh-cut produce, and a suitable postharvest step for removing chemical and biological contaminants, improving conservation and recycling process water. They observe that uptake at industrial level has been slow, partly because of the high capital investment and running costs involved. They call for further work to identify the products for which ozone is genuinely effective, to combine it with complementary methods such as UV light, high hydrostatic pressure and sonication, and to establish safe exposure limits for operators.

Limitations of this review

This is a narrative review rather than a systematic review or meta-analysis, so the underlying studies were not selected or pooled against pre-defined criteria and the strength of the combined evidence is not formally graded. Those studies use different produce, ozone concentrations, delivery methods and outcome measures, which makes direct comparison difficult, and much of the work is laboratory or pilot scale rather than full commercial operation. The review was published in 2013, so it does not capture more recent research or equipment. It concerns food sanitation and storage only and makes no claims about human health or the consumption of ozone.