Fractionation of corn fiber treated by soaking in aqueous ammonia (SAA) for isolation of hemicellulose B and production of C5 sugars by enzyme hydrolysis.

A process was developed to fractionate and isolate the hemicellulose B component of corn fiber generated by corn wet milling. The process consisted of pretreatment by soaking in aqueous ammonia followed by enzymatic cellulose hydrolysis, during which the hemicellulose B was solubilized by cleavage into xylo-oligosaccharides and subsequently recovered by precipitation with ethanol. The pretreatment step resulted in high retention of major sugars and improvement of subsequent enzymatic hydrolysis. The recovered hemicellulose B was hydrolyzed by a cocktail of enzymes that consisted of ß-glucosidase, pectinase, xylanase, and ferulic acid esterase (FAE). Xylanase alone was ineffective, demonstrating yields of less than 2% of xylose and arabinose. The greatest xylose and arabinose yields, 44% and 53%, respectively, were obtained by the combination of pectinase and FAE. A mass balance accounted for 87% of the initially present glucan, 91% of the xylan, and 90% of the arabinan. The developed process offered a means for production of corn fiber gum as a value-added co-product and C5 sugars, which could be converted to other valuable co-products through fermentation in a corn wet-milling biorefinery.

Phosphorus runoff relationships for Louisiana Coastal Plain soils amended with poultry litter.

Long-term application of poultry (Gallus gallus domesticus) litter has built high levels of P in certain Coastal Plain soils of north Louisiana. However, soil P/runoff P relationships for soil and environmental conditions of the area have not been examined. This study measured soil P (total, Bray 1, Bray 2, Mehlich 3, resin-exchangeable, and water-extractable) and runoff P (dissolved P, DP; and total P, TP) at four pasture sites previously amended with poultry litter. Sites varied in soil P due to annual litter applications ranging from 1 to more than 20. Three replicated plots at each site were subjected to simulated rainfalls over 2 yr, and concentrations of DP and TP in runoff were measured and related to soil P. This allowed examination of soil P/runoff P relationships and their changes over time. Runoff DP was also related to DP desorbed from surface soil in a miscible displacement experiment. Among measures of soil P, only resin-exchangeable and water-extractable P showed significant decreases over 2 yr. These measures of soil P explained 54 to 64% of the variability in runoff DP data. However, the miscible displacement technique proved the best indicator of runoff DP, explaining 70% of the variability. Runoff varied among sites (decreasing with increasing years of litter application), limiting the predictive capability of the soil extraction methods. Linking runoff characteristics with miscible displacement data may be a useful predictive tool and warrants further examination.