Effect of ozone treatments on the removal of pesticide residues and postharvest quality in green pepper

Background: pesticide residues and shelf life on fresh peppers

Green peppers are a widely eaten fresh vegetable, but like many field crops they can carry pesticide residues on their skin at harvest, and they lose quality quickly once picked. Washing produce with chemical sanitisers is one option, yet growers and packers have looked for approaches that leave no lasting residue of their own. Ozone dissolved in water, or applied as a gas, is a strong oxidant that breaks down on contact and leaves only oxygen behind, which has made it a candidate for both cleaning produce and extending storage life. This study set out to test whether ozone could do both jobs at once on green pepper: reduce pesticide residues and preserve postharvest quality during storage.

Study design: ozone in water and air compared with untreated peppers

The researchers treated green peppers with ozone applied either dissolved in water or delivered in air, and compared them against untreated control samples. A concentration of 2 ppm ozone was among the treatments assessed. After treatment, peppers were packed in polystyrene trays covered with 12 micron stretch film and held at 20 degrees Celsius and 60 plus or minus 5 percent relative humidity for eight days, reflecting typical room-storage conditions. Across the storage period the team measured pesticide residue levels, weight loss, respiration rate, skin colour (reported as hue angle, h degrees) and external appearance, so that both the cleaning effect and the eating quality could be tracked over time.

Findings: ozonated water at 2 ppm performed best overall

The way ozone was applied affected how much pesticide residue was removed from the pepper surface. Ozonated water containing 2 ppm ozone was the most effective treatment for degrading pesticide residues. Ozone-treated peppers also lost less weight than the controls during storage and kept their green colour better, with ozonated water giving the most vivid green skin as reflected in a higher hue angle. Although the external appearance scores did not differ significantly between treatments, ozonated water at 2 ppm scored highest by the end of storage. Ozone treatments lowered respiration rates by slowing the peppers' metabolism throughout storage. Peppers treated with 2 ppm ozone, in water or in air, kept good quality for eight days under the trial conditions, whereas control samples lost their marketable quality after six days.

What the authors concluded

The authors concluded that ozone treatment, and ozonated water in particular, can serve as an alternative tool for removing pesticide residues and preserving the postharvest quality of green peppers during storage. They noted that ozonated water at 2 ppm consistently gave the best combination of residue removal, colour retention, reduced weight loss and slower respiration, and that this offered a practical, residue-free option for handling peppers after harvest.

Limitations of this study

The authors were clear that further, more detailed work is needed to establish the appropriate ozone dose and application method for both pesticide removal and storage. The trial was carried out on a single crop, green pepper, so the results may not transfer directly to other fruit and vegetables. Storage was tested under room conditions at 20 degrees Celsius rather than refrigerated cold-chain conditions, and the eight-day window was relatively short. The study examined ozone as a postharvest produce-treatment and food-safety measure only; it does not concern human health treatment of any kind.