Algae-based coatings and packaging films
Seaweed is a traditional ingredient in Asian cuisine. However, it can also be used as a raw material for the extraction of algae-specific polysaccharides such as alginate, carrageenan and agar. The latter substances are now being used in industrial sectors such as food production, biotechnology, paper production and printing. Marine algae can play a key role in a biobased circular economy of the future. Not only are they a rapidly renewable resource that can be harvested in a sustainable manner; they also contain many valuable ingredients. Yet for many of the polysaccharides contained in algae, such as ulvan and fucoidan, as well as other small-molecule antimicrobial ingredients, further research work is still required to investigate their suitability for use in industrial applications.
It is already known, for example, that when algal polysaccharides are used to coat packaging films, this greatly improves their barrier properties against oxygen. In the case of most foodstuffs, any packaging must offer an adequate oxygen barrier in order to ensure proper protection. To date, the material of choice is conventional, hydrocarbon-based packaging, which comprise multilayer composites that are difficult to recycle. In countries without an effective refuse-collection system, more and more plastic waste is being released into the environment. This in turn causes the formation of microplastics in the sea and soil, thereby creating long-term global problems for the environment. Food packaging made from algal polysaccharides may well offer an alternative here. Not only is such packaging biodegradable and made almost entirely from biological materials; it also has technical and functional properties comparable to those of conventional food packaging.
ACCEPT: a holistic approach
ACCEPT is a CORNET project to investigate the use of marine algae as a feedstock for biobased packaging materials, as an edible coating for freshly harvested fruit, and as an environmentally friendly pesticide. The project consortium is made up of research and industry partners from Germany (Fraunhofer Institute for Process Engineering and Packaging IVV and the German Industry Association for Food Technology and Packaging (IVLV)) and Brazil (Companhia das Algas, USP – Universidade de São Paulo, UNESP – Universidade Estadual Paulista, and ITAL – Instituto de Tecnologia de Alimentos) along with a committee of small and medium-sized enterprises.
Local fishing families in northeastern Brazil collect, clean and dry the naturally occurring seaweed. This provides them with an additional source of income. Some of the algae is processed in Brazil, where it is applied as an aqueous extract or gel to freshly harvested fruit in order to prevent it from spoiling. At the same time, the algae is now being tested as a natural pesticide for crops. As such, these products can help prevent food waste and also protect the soil and groundwater by reducing the use of chemical pesticides.
From flotsam to packaging
Meanwhile, back in Germany, Fraunhofer IVV is using a specially developed fractionated extraction process on part of the algae biomass collected in Brazil. Here, the challenge is to obtain the purest possible extracts from this natural algal mix. These have to have a consistent chemical composition and therefore show controllable technical and functional characteristics such as film formation, drying behavior and barrier properties. These extraction processes are to be scaled up to the pilot level at Fraunhofer IVV’s pilot facilities. The extracts obtained in this way will then be used – either in their natural or a modified form – in packaging materials. For example, chemical modification (cross-linking) of the polysaccharides increases their resistance to moisture. The applications primarily of interest here are coatings for conventional biopolymer films (e.g., PLA) and for paper so as to endow it with enhanced barrier properties. At the same time, there are also plans to develop standalone algae-based films – a novel material that could be used for various applications in the packaging industry. If all goes to plan, these materials should be available in sheet form before project completion.
Depending on the final properties, these new films will be used to protect either dry and semi-dry foodstuffs, or fresh products with a short shelf life. By offering access to a new and more environmentally aware customer base, these materials will strengthen the hand of SMEs in the food and packaging sector. What is more, they not only fulfill legislative requirements for more sustainable packaging but also guarantee that packaged foodstuffs do not spoil before the end of their shelf life.