Postharvest losses of fruits and vegetables present a significant operational challenge across the global supply chain. Microbiological contamination, pesticide residues, and physiological degradation during storage and transport impact shelf life, food safety, and product availability for industry stakeholders.
As pressure mounts on the food industry to adopt safer, more sustainable practices, ozone (O₃) has emerged as a viable alternative to conventional chemical disinfectants for postharvest preservation.
Why Postharvest Preservation Matters
Fruits and vegetables are vital to the human diet, delivering vitamins, minerals, fibre, and bioactive compounds that reduce chronic disease risk. Despite this value, significant losses occur after harvest, mainly due to microbial spoilage and insufficient sanitation.
Traditional postharvest sanitation depends on chlorine-based disinfectants. These compounds, while effective, can generate by-products such as trihalomethanes and haloacetic acids, raising significant health and environmental concerns. As a result, the industry seeks safer, residue-free alternatives.
Why Ozone Is Gaining Ground
Ozone is recognised as an efficient and sustainable sanitising agent for industrial applications, owing to its strong oxidising properties. This enables the inactivation of a broad spectrum of pathogenic microorganisms and the effective degradation of pesticide residues, all without generating toxic by-products.
Following treatment, ozone decomposes naturally into oxygen, leaving no chemical residue on produce. This residue-free aspect makes ozone a suitable choice for food sanitation, contributing to regulatory acceptance and enabling its use for diverse food-related applications, including those approved by the FDA in the United States. Ozone preserves the sensory and nutritional quality of produce, supporting consumer acceptance and extending shelf life during storage and transportation.
How Ozone Works in Postharvest Applications
Ozone’s high oxidation–reduction potential (2.07 V) makes it a highly effective sanitiser.
Its action occurs through three primary mechanisms:
- Direct oxidation, where reactive oxygen species damage microbial cell membranes, proteins, and nucleic acids
- Indirect oxidation, through the formation of free radicals during ozone decomposition
- Ozonolysis, where ozone reacts directly with double bonds in organic molecules, altering their chemical structure
These mechanisms quickly inactivate bacteria, yeasts, and moulds, causing spoilage.
Methods of Ozone Application
Ozone is applied as a gas, ozonated water, or ozonated mist, depending on product and process needs.
- Gaseous ozone, used in storage rooms and controlled atmospheres
- Ozonated water is used for washing and surface disinfection.
- Ozonated mist, providing enhanced surface contact with reduced water usage
Each method offers distinct benefits and should be chosen based on product sensitivity, processing conditions, and targeted results.
Engineering and Control Considerations
Effective use of ozone needs precise control of exposure, concentration, temperature, and product sensitivity.
Ozone’s instability means water purity, pH, temperature, and turbulence affect solubility and persistence.
High temperature, high pH, and impurities accelerate ozone decomposition, requiring careful system design.
Ozone Generation Technologies
Ozone is generated by splitting O2 into atoms that recombine to form O3, using:
- Ultraviolet (UV) radiation, using wavelengths between 140 and 185 nm
- Electrochemical generation, producing ozone in an electrolytic solution
- Corona discharge is the most widely used method in commercial applications.
Corona discharge systems generate high ozone using pure oxygen between electrodes, improving efficiency by avoiding nitrogen and moisture.
While corona discharge systems require energy management and maintenance, they are the primary choice for industrial-scale postharvest ozone production.
Why System Design Matters
Ozone’s effectiveness depends not only on its chemical properties, but on how it is generated, delivered, dissolved, and monitored. Inadequate system design may lead to undertreatment, reduced microbial control, ozone losses, or operational risks. Effective ozone systems must balance performance, safety, and stability for each product and process.
This is where engineering expertise becomes essential.
Ozone is a robust, residue-free solution for postharvest preservation. Its ability to inactivate pathogens, degrade pesticide residues, and maintain product quality makes it an increasingly attractive alternative to chemical sanitisation.
Ozone’s high reactivity and sensitivity to environmental factors require robust engineering and operational controls. Implemented correctly, ozone supports food safety, regulatory compliance, and sustainable practices throughout the postharvest supply chain.
Biozone Manufacturing engineers ozone systems to ensure performance, safety, and operational reliability in postharvest environments, meeting the demands of industrial clients.