By combining packaging innovation with in-house automation expertise, Opal has engineered a paper-based punnet and custom de-nester, making fibre a viable alternative to plastic at national retail scale.
For years, the barrier to replacing plastic in fresh produce has not been intent – it has been engineering. Blueberries are packed at speed, in high volumes, on lines designed for rigid PET. Without machinery capable of handling fibre formats reliably at scale, paper-based alternatives have struggled to move beyond limited trials.
Opal’s latest collaboration addresses that constraint directly – pairing a kerbside recyclable paper-based punnet with a purpose-built de-nester engineered specifically for cardboard. The result is a commercially viable system now operating at scale.
Concept to commercial reality
Opal, in partnership with Mountain Blue and Coles, launched a kerbside recyclable paper-based punnet trial for blueberries as a replacement for plastic PET containers.
Blueberries are machine-packed at speed, a key requirement for national commercial supply. Plastic punnets have long dominated the category because of their durability and compatibility with high-speed packing lines. Research indicates that eight plastic punnets are used for every kilogram of blueberries sold in Australian supermarkets, generating a substantial amount of plastic annually.
While there are signs that consumers are looking for alternatives to plastic during their fresh produce shop, common challenges with plastic-replacement formats include reduced visibility, limited durability, recyclability concerns and slow, manual packing processes.
Engineering the fibre shift
To ensure the paper-based punnets could integrate seamlessly into Mountain Blue’s existing high-speed lines, Opal’s in-house packaging automation team engineered a custom cardboard de-nester.
The system can process up to 250 paper-based punnets per minute with minimal line changes. Designed specifically for cardboard’s friction and flex characteristics, the de-nester separates and places each punnet with precision on to the packing line.
Lewis Worthing, head of customer machinery solutions ANZ at Opal, says the development addressed a long-standing technical gap.
“Our purpose-built de-nester is designed for cardboard punnets to run smoothly and reliably at full production speed. It’s changing the game for fresh produce packhouses,” he says.
“For decades, packing lines were built for rigid plastic. Cardboard flexes and grips differently, which caused standard de-nesters to jam, slow down or fail entirely. When Mountain Blue committed to trialling cardboard-based punnets for Eureka, there was no machine available that could do the job at commercial speed, so we engineered a cardboard-first solution.”
The de-nester is designed to drop into existing lines without requiring packhouse rebuilds. Its compact modular frame integrates with conveyors and controls, while operators benefit from tool-less changeovers, a modern user interface and consistent performance.
Without this automation solution, the paper-based punnet would not be possible at commercial scale.
Josh McGuiness, CEO of The Berry Collective, says the combined solution demonstrates what collaboration can achieve: “The punnet and de-nester solution speaks to the courage to lead, the strength of partnership and the proof that bold ideas can succeed at scale,” he says.
Rethinking the punnet
To meet market requirements, Opal produced a paper-based punnet made from recycled FSC-certified paper (FSC-C113466) sourced from Opal’s Botany Paper & Recycling plant, combined with a PEFC-certified cellulose window derived from wood pulp.
The paper-based punnet is food-safe, requires no soaker pads and is kerbside recyclable. It is designed to match plastic in protection and shelf life, aligning with Mountain Blue’s performance requirements.
Full-panel printing showcases Opal’s print capabilities and enhances on-shelf branding, eliminating the need for separate labels and labelling machines.
David Pointer, GM Corporate Business at Opal, says the project reflects the company’s approach to sustainable packaging innovation.
“Opal prides itself on striving for sustainable packaging innovation and being at the forefront of customer and consumer needs. In collaboration with Mountain Blue, we developed a high-performing, market-leading paper-based punnet solution, providing an alternative to traditional plastic punnets,” Pointer says.
McGuiness adds that the move strengthened Mountain Blue’s market position.
“It shows our industry what is possible when a grower listens to its customers and works with the right partners to bring a vision to life,” he says.
“The solution strengthened our brand as an industry leader, created a clear point of difference on-shelf, and aligns us with the values and expectations of our customers and partners. We’re incredibly grateful to Opal for their expertise and commitment in helping us make this step forward.”
Trial proves punnet promise
Following a 2024 trial in 34 Coles stores, the program expanded across New South Wales in 2025.
Opal says the paper-based punnet and de-nester solution is an example of its commitment to supporting Australia’s circular economy for packaging across all major Australian industries.
The integrated solution maintains product and packing efficiency while enabling a cost-effective transition to cardboard packaging. Mountain Blue gains first-to-market advantage and enhanced retailer appeal, while the system demonstrates that paper-based formats can be functional, efficient and commercially viable.
This article was first published in PKN Packaging News March issue, page 14.
