Melih Soner Celiktas

Bioethanol production from raffinate phase of supercritical CO2 extracted Stevia rebaudiana leaves

The extracts of Stevia rebaudiana are marketed as dietary supplements and utilized as natural sweetening agent in food products. Subsequent to extraction on industrial scale, large quantities of solid wastes are produced. The aim of this study was to investigate the bioconversion efficiency of supercritical CO(2) extracted S. rebaudiana residues. Therefore, leaves were extracted with supercritical CO(2) and ethanol mixture in order to obtain glycosides, then the raffinate phase was hydrolyzed by both dilute acid and various concentrations of cellulase and β-glucosidase cocktail. The maximum yield of reducing sugars reached 25.67 g/L under the optimal conditions of enzyme pretreatment, whereas 32.00 g/L was reached by consecutive enzymatic and acid hydrolyses. Bioethanol yield (20 g/L, 2.0% inoculum, 2 days) based on the sugar consumed was 45.55% corresponding to a productivity of 0.19 kg/m(3)h which demonstrates challenges to be utilized as a potential feedstock for the production of bioethanol.

Biorefineries for wheat bran: Sustainable utilization and market potential

Abstract Biobased products can be manufactured from various feedstocks. The increasing need for these products is the driving force for the growth of the biorefinery market. There is an ongoing debate whether bioproducts will replace fossil-based products. This chapter provides an overview of recent studies on the biorefinery concept and investigates its possible use for conversion of wheat bran into value-added biobased products. A large number of methods and technologies have been researched and developed, resulting in high recovery of sugars and value-added products. An overview of end products and by-products of wheat bran using diverse biorefinery concepts and their applications in the main sectors is demonstrated. In addition, market potential provides economic and scientific insights, and novel biorefinery concepts are identified and discussed in spite of comparing various biomass conversion technologies. This chapter also provides an outline of various steps involved in biochemical conversion of carbohydrates to biofuels, bioethanol, and biobutanols, and conversion of natures most abundant aromatic polymer, lignin, to value-added products. The limitations of biomass development, lignocellulose deconstruction, specialty fuels, and bioproduct development from biomass are discussed by considering most of the workshop results together with future opportunities for basic research in support of a sustainable and commercially viable advanced biofuels and bioproducts industry. Bioeconomy is the sustainable production and conversion of biomass for a range of food, health, fiber, industrial, and energy products through the application of biotechnologies in biorefineries using nonfood plants and trees for industrial purposes. This chapter researches recent global trends and developments of scientific studies in the field of biorefinery concepts. The products of knowledge-based biorefinery are expected to have a one-third share of industrial production.