tailieunhanh - Biodiesel Quality Emissions and By Products Part 16

Tham khảo tài liệu 'biodiesel quality emissions and by products part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 364 Biodiesel - Quality Emissions and By-Products Zinn M. Hany R. 2005 . Tailored material properties of polyhydroxyalcanoates through biosynthesis and chemical modification. Advanced Engineering Materials pp. 408-411 ISSN 1527-2648 20 Utilization of Crude Glycerin in Nonruminants Brian J. Kerr1 Gerald C. Shurson2 Lee J. Johnston2 and William A. Dozier III3 1USDA-Agricultural Research Service 2University of Minnesota 3Auburn University United States of America 1. Introduction During digestion in non-ruminants intestinal absorption of glycerol has been shown to range from 70 to 90 in rats Lin 1977 to more than 97 in pigs and laying hens Bartlet and Schneider 2002 . Glycerol is water soluble and can be absorbed by the stomach but at a rate that is slower than that of the intestine Lin 1977 . Absorption rates are high likely due to glycerin s small molecular weight and passive absorption rather than forming a micelle that is required for absorption of medium and long chain fatty acids Guyton 1991 . Once absorbed glycerol can be converted to glucose via gluconeogenesis or oxidized for energy production via glycolysis and citric acid cycle with the shuttling of protons and electrons between the cytosol and mitochondria depicted in Figure 1 Robergs and Griffin 1998 . Glycerol metabolism largely occurs in the liver and kidney where the amount of glucose carbon arising from glycerol depends upon metabolic state and level of glycerol consumption Lin 1977 Hetenyi et al. 1983 Baba et al. 1995 . With gluconeogenesis from glycerol being limited by the availability of glycerol Cryer and Bartley 1973 Tao et al. 1983 crude glycerin has the potential of being a valuable dietary energy source for monogastrics. 2. Crude glycerin Caloric value for swine and poultry Pure glycerin is a colorless odorless and a sweet-tasting viscous liquid containing approximately Mcal of gross energy GE kg as-is basis Kerr et al. 2009 . However crude glycerin can range from 3 to 6 Mcal GE kg .