A Review into the Effectiveness of Ozone Technology for Improving the Safety and Preserving the Quality of Fresh-Cut Fruits and Vegetables

Background

Fresh-cut fruit and vegetables are amongst the most fragile foods sold at retail. Once produce is peeled, cut or otherwise processed, its protective outer surface is broken and its tissue is directly exposed to air, handling and water. Consumers increasingly seek out fresh, minimally processed produce for its nutritional benefits, but the very processes that make it convenient - cutting, peeling, washing and packaging - accelerate biochemical, sensory and microbial deterioration. Contamination can occur directly on the raw material itself, or as cross-contamination during preparation steps such as washing. Researchers at the University of Tuscia in Italy set out to review the scientific literature on one candidate solution to this problem: ozone.

Study design

This is a literature review, not a new laboratory experiment. The authors gathered and analysed existing published studies that had tested gaseous ozone and ozonated water treatments on a range of fresh-cut fruits and vegetables, examining effects on microbial growth (bacteria, yeasts and moulds) and on quality markers such as colour, firmness and nutrient retention. The studies reviewed varied in the produce tested, the ozone concentrations used, the contact time, and the temperature at which treatments were applied, allowing the authors to compare outcomes across many different experimental conditions rather than a single controlled trial.

Findings

Across the studies reviewed, ozone treatment - whether applied as a gas or dissolved in water - was generally effective at reducing microbial loads on fresh-cut produce, with reported reductions of roughly one to three and a half log units depending on the conditions used. In many cases, ozone treatment also helped preserve quality attributes such as colour and firmness compared with untreated produce. Results were not uniform, however: some studies reported diminished nutrient content or altered sensory qualities at higher ozone concentrations or longer exposure times, and effectiveness varied considerably depending on the type of produce, the ozone dose, and the method of application.

What the authors concluded

The authors concluded that ozone technology, when applied at the right concentration and contact time for a given product, represents a promising and environmentally friendly alternative to chemical sanitisers for fresh-cut produce. They highlighted that ozone's key appeal is that it breaks back down into oxygen after use, leaving no chemical residue on the food or in wastewater, unlike the chlorine-based washes commonly used across the industry.

Limitations of this study

As a literature review rather than original research, this paper's conclusions are only as strong as the individual studies it draws upon, and the authors themselves note inconsistencies between studies in terms of outcomes and optimal treatment parameters. Ozone's effectiveness appears highly dependent on getting the concentration, contact time, temperature and application method right for each specific fruit or vegetable, meaning findings from one produce type cannot necessarily be generalised to another. The review does not present new experimental data of its own, and, as with any food-safety technology, results achieved under controlled laboratory conditions may differ from those seen in a commercial washing or processing environment.