(452b) Valorization of Bioenergy Crops for Recovery of Anthocyanins and Sugars

The increased awareness for eco-friendliness and sustainability has shifted the interest of stakeholders from synthetic colorants to natural plant-based pigments. In order to meet the large-scale demand for natural pigments in industrial applications, the process should be economically viable and environmentally sustainable along with abundant supply of the feedstock. The presence of industrially relevant pigments (mainly anthocyanins) in bioenergy crops such as miscanthus, sorghum and sugarcane^1-5 has been reported in literature. The red pigment present in the leaf sheaths of sorghum, is rich in 3-deoxyanthocyanins, which are known for their stability to heat treatments and pH changes, making them a valuable source of natural colorants for industrial applications. In the case of sugarcane and miscanthus, the color is mostly concentrated in the stem and could be extracted before processing the crop for production of biofuels. In this study, miscanthus was analyzed for its total anthocyanin content (TAC) and structural carbohydrate composition. TAC was determined by a two-staged extraction method. The dried and ground biomass sample was mixed with acidified ethanol and was continuously stirred at room temperature for 1 h. The mixture was filtered and the filtrate was analyzed for the anthocyanin content by the pH differential method⁶. Solids retained on filter paper were recovered and extracted using acidified ethanol for 2 h for determining remaining anthocyanin content. The TAC was obtained as the sum of the anthocyanin content from the two sequential extractions and was in the range of 10.2 to 73.4 µg/g of biomass. The concentration of glucan and xylan in miscanthus ranged between 37.6 to 43.7% and 18.2 to 26.4%, respectively. After the extraction of anthocyanin, the residual biomass could be enzymatically hydrolyzed into sugar monomers which could be fermented to biofuels. Recovering anthocyanins from bioenergy crops in an integrated biorefinery would increase the overall profitability due to the increased revenue from this high-value co-product.

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