Biorefining produces higher value products than other routes for biomass utilisation but often involves more processing with additional costs. To ensure economic sustainability all inputs need to be converted to useful products with minimum processing steps.
Crustacean shell, the major by-product from scampi, prawn and crab meat processing contains 20-30% chitin. Chemically extracted chitin is sold as a horticultural bio-stimulant and is the main source for glucosamine used to combat arthritis, while chitosan has a broad commercial market including the agricultural, water treatment, medical and personal care sectors. Chitin and other potential high value components within shells such as proteins, flavouring compounds and astaxanthin, can be degraded when chitin is extracted chemically.
Lactic acid has been identified as a more benign approach to chitin extraction. However, no commercial process operates yet in Europe, due to the cost of lactic acid production. Perennial ryegrass, which produces high yields of fermentable sugars, fibre, protein and pigments, has been identified as a potential economic feedstock for a commercial lactic acid biorefinery.
The innovative iCRAB (integrated Chitin Ryegrass Acid Biorefinery) project led by Pennotec and based at the Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University is looking to improve the economics of both chitin extraction and lactic acid production by combining the two in a single biorefinery process. Lactic acid dissolves calcium carbonate in the shell, which buffers the fermentation, increasing lactic acid yield. Other synergistic benefits of adding shell to the biorefinery are economic – shell-derived products including chitin provide a high value product stream, and environmental – perennial ryegrass can grow on reclaimed land and shell is diverted from landfill.
More details about the iCRAB project and the application of industrial biotechnology processes for the valorisation of waste biomass can be found here