Berries—strawberries, blueberries, raspberries, and their cousins—are among the most beloved fruits worldwide. They’re rich in nutrients, packed with antioxidants, and in high demand from both health-conscious consumers and gourmet food markets. But their delicate nature makes them highly perishable, with spoilage often occurring within days of harvest.
Traditional preservation methods, such as cold storage or modified atmosphere packaging, can slow down deterioration but are not always enough to maintain optimal quality during transportation and shelf display. As the industry looks for cleaner, more sustainable, and regulation-friendly technologies, ozone has emerged as a promising candidate.
This article explores how ozone technology is being applied to extend the shelf life of berries, reduce microbial spoilage, and preserve their visual and nutritional quality—all without leaving behind chemical residues.
1. Understanding Spoilage in Berries
Unlike harder produce, berries deteriorate quickly due to their soft tissues, high respiration rates, and susceptibility to microbial contamination. Common causes of spoilage include:
Enzymatic degradation: Enzymes like polyphenol oxidase (PPO) break down cell walls, leading to softening and browning.
Fungal growth: Moulds such as Botrytis cinerea thrive in high-moisture environments, causing visible decay.
Water loss and desiccation: Leads to wrinkling and shriveling, especially in storage environments with fluctuating humidity.
Oxidative stress: Natural degradation of anthocyanins and polyphenols reduces colour vibrancy and antioxidant content.
Even with temperature control, these mechanisms can advance rapidly, especially once the cold chain is broken. This makes berries one of the trickiest fresh produce categories to store and transport efficiently.
2. What Is Ozone and How Does It Work?
Ozone (O₃) is a naturally occurring molecule composed of three oxygen atoms. Known for its strong oxidising power, ozone is widely used in water treatment, air purification, and food processing due to its ability to inactivate bacteria, moulds, yeasts, and viruses.
When applied to fresh produce, ozone serves multiple functions:
Microbial control: Ozone disrupts cell membranes of spoilage organisms, significantly reducing microbial load without the need for synthetic chemicals.
Ethylene degradation: Ozone can break down ethylene gas, slowing down ripening and senescence in ethylene-sensitive fruits.
Enzyme regulation: It has been shown to influence the activity of enzymes like PPO and peroxidase (POD), both of which are associated with browning and softening in fruit.
Surface sanitation: In gaseous or aqueous form, ozone can sanitise fruit surfaces and packaging materials, further extending product life.
Unlike many traditional sanitisers, ozone decomposes back into oxygen, leaving no chemical residues—a major advantage for organic and “clean label” operations.
3. Research on Ozone’s Effects in Berries
Several peer-reviewed studies and pilot trials have demonstrated that ozone can be an effective postharvest treatment for berries:
Blueberries
A 2022 study published in Frontiers in Plant Science reported that ozone fumigation helped preserve firmness and reduce degradation of total phenolics and anthocyanins in blueberries. It also suppressed polyphenol oxidase (PPO) activity while boosting peroxidase (POD) and catalase (CAT), all of which help mitigate oxidative damage and extend shelf life.
Strawberries
Other research has shown that ozone exposure can inhibit the enzymes responsible for cell wall breakdown, helping strawberries maintain their texture during storage. Ozone also improves energy metabolism, allowing cells to maintain membrane integrity and delay senescence.
Raspberries
Due to their delicate structure, raspberries are notoriously difficult to store. Trials using ozone treatments demonstrated a reduction in microbial decay, along with preservation of colour and aroma compounds—key attributes for consumer acceptance.
4. Considerations for Commercial Implementation
Ozone can be applied in two main forms: gaseous and aqueous. Gaseous ozone is often used in cold storage rooms, where it can circulate evenly through crates and pallets. Aqueous ozone, on the other hand, is commonly used during pre-cooling or washing stages, providing rapid surface sanitation.
Some key factors to consider when integrating ozone:
Dosage: Too low, and it’s ineffective; too high, and it can cause cellular damage or off-odours. Precision is key.
Exposure time and frequency: Intermittent low-dose applications often yield better results than single high-dose treatments.
Ventilation and distribution: Homogeneous airflow in storage areas ensures even treatment.
Worker safety: While ozone is generally safe when used properly, monitoring systems should be in place to keep workplace concentrations within regulated limits.
Ozone systems can be retrofitted into many existing storage facilities and integrated with automated sensors and IoT controls for optimal performance.
5. Commercial Potential and Market Relevance
The benefits of ozone go beyond shelf life:
Reduced waste: Less spoilage during transit and in retail.
Higher product quality: Maintained firmness, appearance, and aroma = better consumer satisfaction.
Chemical-free marketing: Supports organic certification and appeals to health-conscious consumers.
Export opportunities: Longer shelf life enables access to more distant markets with less risk.
For berry growers, packers, and distributors, ozone technology offers an opportunity to reduce postharvest losses while meeting rising regulatory and market demands for sustainable practices.
Ozone is proving to be a versatile and effective postharvest technology for berries. With its strong antimicrobial action, ability to preserve firmness and nutritional quality, and its status as a residue-free “green” solution, ozone is uniquely positioned to support the fresh produce industry in a time of increasing sustainability pressure.
As more producers look to future-proof their operations and reduce reliance on chemical preservatives, ozone may well become a cornerstone of modern, clean postharvest management.