Paua and Biopolymers at Scion

December 2016

Incorporating paua in biopolymers at Scion

Scientists at Scion are working with Moana NZ, a pāua aquaculture farm that is part of Aotearoa Fisheries (and was previously known as ‘OceaNZ Blue) to produce a 3D printed bio-plastic containing pāua shells, as a technology demonstrator for a value added pāua biomass side stream.

We live in a world where sustainability and the full utilisation of primary resources is becoming increasingly important for the survival of the planet and for appealing to consumers who want products with a ‘sustainable story’.

Biomass by-products/side-streams are often overlooked even though they are sustainable resources that can offer additional economic opportunities for industries.

Biomass side streams and bioplastic applications are often mentioned in the context of the sustainable bioeconomy. The bioeconomy encompasses the production of renewable biological resources and their conversion into food, feed, bio-based products and bioenergy via innovative and efficient technologies provided by industrial biotechnology.

A key element to the bioeconomy is considering the whole resource from the beginning. Scion is continuously advancing the fundamental research to convert primary industry side-streams into value-added products that contribute to, and reinforce, a sustainable bioeconomy.

Pāua shell is a ‘side stream’ of the food industry and currently sold off cheaply to off-shore processors who convert them into decorative veneers, powders for cosmetics and homeopathy treatments. Some of these products are exported back to New Zealand. Pāua shells are also incredible biocomposites that exhibit great mechanical properties such as toughness.

With these factors in mind, Scion partnered with the pāua aquaculture farm OceaNZ Blue to investigate the properties of pāua shells and innovative applications. For OceaNZ Blue, sustainable aquaculture practice is an important part of their brand and company ethos. Teaming up to develop a value-added product or process for pāua shells aligned perfectly with both organisations’ visions.

Pāua shells are mostly (approx. 95%) calcium carbonate. Calcium carbonate has several crystalline forms, and two of them, calcite and aragonite, are found in the shells. It is the presence and arrangement of aragonite crystals and proteins in the inner layer of the shell (the nacre) that give pāua its characteristic appearance when viewed in daylight. The iridescent swirl of intense green, blue, purple, and sometimes pink colours, make it an object of great beauty. As the pāua grows, more layers of aragonite are added to the lip of the shell. The inner portion of the shell gets thicker and the nacre color becomes more intense.

Crown Research Institute Scion is investigating the influence of the appearance and mechanical properties of pāua shells on bioplastics. In particular, this means replicating the toughness of the shells but also exploring the beauty and iridescent colors of the pāua shell.

The first question that comes to mind is, why? Florian Graichen, Science Leader- Biopolymers and Chemicals at Scion, uses the analogy of the printer. “We started with black and white and soon progressed to colour – people are always looking for new and better options.”

One then immediately asks, surely there’s an easier way to get the colour and iridescence of the pāua shell into a 3D printable plastic? Colour pigments are very expensive but also contain toxic heavy metals in some cases, so pāua might offer a better cost and an environmentally-friendly alternative. Florian also adds that ‘story’ is crucial in the market place today – consumers want a sustainable story to accompany their product.

To date Scion scientists have created a 3D printable bio-plastic with pāua. Tiny iridescent specs of the pāua are visible in the plastic but they want to accentuate this. The critical point is finding the sweet spot so that the pāua shells within the bioplastic matrix provide mechanical reinforcement and also a stronger unique aesthetic feature. In terms of research into recreating the colours and iridescent quality, they have some excellent ideas that they are progressing. “We’ve proven the concept that paua shells can be used to make biocomposites for 3D printing, and are now evaluating their performances against industry benchmarks. If viable, this concept may be extended to include other sea shells, possibly generating an additional revenue stream for our fishing industry,” says Florian.

The video ‘Pāua Power’ won the peoples choice award at the ECO-BIO 2016 conference in the Netherlands.