Development of a process scheme for the production of high value functional products from DDGS

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DDGS is the major co-product of bioethanol fermentation and is produced at very large quantities annually worldwide. Currently, DDGS is a low value agro-industrial product produced by distillers or bioethanol factories, and is primarily used as a protein-rich animal feed. A major issue with this application, which reduces its utilisation compared to soybean and canola meals, is its compositional variability, which consequently affects its nutritional quality and digestibility. The aim of the proposed work is to develop a novel, scalable and economically viable process that will transform DDGS into several medium to high value products, namely a prebiotic food ingredient, gluten protein for film packaging, betaine and choline for use as nutritional supplements, and crude dietary fibre. The proposed process is based on the biorefinery concept in which the agricultural raw material is transformed into several value-added streams, which are either end-products or starting materials for secondary processing. Developing such a multi-stream process using DDGS as the raw material would be pioneering for the biorefinery industry as it would add considerable value to DDGS.Prebiotics are non-digestible food ingredients that have a beneficial effect on health through their selective metabolism by bacteria in the intestinal tract, and are attractive prospects in the digestive health market. The objective will be to transform arabinoxylan (AX), which consists 30-50% of DGGS, into arabinooligosaccharides (AXOS); these have been shown to have prebiotic activities and over the last five years have attracted considerable commercial interest. A commercially attractive prospect is to target the production of AXOS with relatively high molecular weights (MW) in an effort to increase the persistence of the prebiotics in the colon and target delivery into the distal region. This would increase the beneficial effects of prebiotics as most of the colonic diseases, principally ulcerative colitis and bowel cancer, predominantly originate in the distal region. Gluten on the other hand consists 30-40% of DDGS and will be used to produce biodegradable film packaging material. The research will focus on extracting and characterising the gluten and evaluating the properties of the films. This will open up new applications for DDGS gluten with high market potential and economic benefits. Finally, betaine and choline have important biological functions for human health and as such they have received a lot of commercial interest as nutritional supplements. They are present in wheat and consequently in DDGS at much higher concentrations than in other natural food sources, and therefore extraction of these compounds from DDGS has considerable economic and market potential.The proposed process consists of several scalable unit operations including the separation of DDGS into a soluble and non soluble stream, the fractionation of the soluble steam into gluten, AX, betaine and choline, the controlled hydrolysis of AX to AXOS, and the purification of AXOS. Key factors influencing the efficiency, scalability and economic feasibility of the process are (i) the development of efficient processing steps for the separation of the raw material into the target compounds, with high yields and purities, (ii) the utilisation of highly active enzymes that lead to the controlled synthesis of AXOS with specific MW and prebiotic activities and (iii) the production of gluten films with suitable morphological and functional properties for commercial use. The work will be carried by a multidisciplinary team of researchers from the University of Reading and Rothamsted Research and will bring together unique expertise in wheat biochemistry, bioprocessing, protein science, food ingredient functionality and gut microbiology.