No description available.

No description available.

In Africa, the grain sorghum (Sorghum bicolor (L.) Moench), is malted to provide the most important ingredient in brewing, malt, which is used primarily for the production of traditional (opaque) sorghum beer. Malting is the germination of cereal grain in moist air under controlled conditions, the primary objective being to promote the development of hydrolytic enzymes which are not present in the ungerminated grain. The malting process can be physically split into three distinct unit operations (viz. steeping, germination and drying). To date, little attention has been given to optimising the conditions of steeping for sorghum. The effects of different steeping variables (time, temperature and aeration) on the quality (in terms of diastatic power (amylase activity), free amino nitrogen and hot water extract) of sorghum malt for brewing were investigated. Malt quality was found to increase with steeping time, over the range 16-40 hours and the optimum steeping temperature was found to be in the range 25 to 30°C. Aeration during steeping appeared to be necessary to maximise the malt quality, particularly when steeping was conducted for long periods at high temperatures. Of particular significance was the observation that final sorghum malt quality was highly significantly correlated (p<0.01) with grain moisture content at steep-out (the end of the imbibition period). When steeping conditions based on these findings were used, a germination temperature of 25-30°C was found to be optimal for sorghum malt quality. As with steep-out moisture, green malt (grain after the specified germination time) moisture content was correlated Significantly (p<0.01) with final sorghum malt quality. The finding that sorghum malt quality is related to steepout moisture content was given further substance when it was shown that the stimulatory effect on sorghum malt quality of steeping sorghum in a dilute solution of alkali, actually increases the amount of water taken up during steeping probably because the alkali disrupted the pericarp cell wall structure of the grain. Barley malting practices have taken advantage of the knowledge that the exogenous application of gibberellic acid can enhance the synthesis of the critically important malt hydrolytic enzyme, a-amylase. To date, literature on the effect of exogenous application of gibberellic acid on sorghum malt quality has been inconclusive; with reports both of no effects, and of positive effects, on amylase activity. To elucidate the possible control mechanisms involved in sorghum germination, a combined HPLC-radioimmunoassay technique was used to determine the levels of selected plant growth regulators from the groups auxin, cytokinins, gibberellins and abscisic acid in sorghum at various stages of germination. Levels of gibberellic acid were low throughout germination. During germination the levels of the other plant growth regulators declined, but a peak in cytokinins followed the first visible signs of root protrusion. The high level of the germination inhibitor and gibberellic acid antagonist, abscisic acid, in the germ (embryo inclusive of scutellum) portion of the mature non-germinated grains was noteworthy. Based on these findings, it was determined that sorghum malt quality could in fact be improved significantly by the application of exogenous gibberellic acid. However, this was effective only if it was administered during the end of steeping or at the beginning of the germination step. By optimising the conditions of steeping and germination and by steeping in dilute NaOH or in gibberellic acid not only should it be possible to enhance the quality of sorghum malt, it should be possible to reduce the time required to obtain the specific quality, thereby offering a saving to the sorghum maltster in terms of operation costs and enhancing the total throughput possible from the malting plant. / Thesis (Ph.D.)-University of Natal, Durban, 1997.

El tema del presente trabajo es la instalación de una planta productora de licor de higo fermentado para el mercado limeño, dicho producto busca ser considerado como una nueva opción para el consumo de bebidas alcohólicas, se puede tomar en toda ocasión, principalmente como acompañamiento en las comidas. / The theme of this project is the installation of a fig liqueur plant for the Lima market, this product is intended to be considered as a new option for consumption of alcoholic drinks, it can be drunk at all times, mainly as accompaniment in foods. / Trabajo de investigación

The Bayer process for the production of alumina (A1203) from bauxite involves a perennial gibbsite (y-Al(OH)3) precipitation step, relating to an inherently slow crystal growth from supersaturated sodium aluminate solutions (pregnant Bayer liquors). The kinetics and mechanisms involved in the transformation of the tetrahydroxo, Al(III)-containing species in solution into octahedrally-coordinated Al(OH)3 crystals in the presence of NA+ and excess of ions, are as yet not fully known. To gain further knowledge and better understanding of the nature of solution species, their specific interaction and participation in the gibbsite crystallization mechanisms, the role alkali ions play in the kinetic behaviour and mechanisms of nucleation, growth and aggregation/agglomeration from caustic aluminate solutions of industrial strength has been investigated.

No description available.

No description available.

Environmental concerns and cost reduction have been the focus of pretreatment and extended delignification in Kraft pulping for some time now. Previous work has looked at the diffusion of tritiated water into softwood chips. This thesis looks at the diffusion of Na2S into southern pine softwood chips. Two size fractions were used. The measured diffusion data were compared to the equilibrium of mixing between the HS ion and water alone. Since pine is porous, effective diffusivities were calculated for each size fraction using a 1-dimensional model. Tortuosities were then calculated for the HS / pine wood system. These diffusivities are compared to values previously obtained for tritiated water.

The Bayer process for the production of alumina (A1203) from bauxite involves a perennial gibbsite (y-Al(OH)3) precipitation step, relating to an inherently slow crystal growth from supersaturated sodium aluminate solutions (pregnant Bayer liquors). The kinetics and mechanisms involved in the transformation of the tetrahydroxo, Al(III)-containing species in solution into octahedrally-coordinated Al(OH)3 crystals in the presence of NA+ and excess of ions, are as yet not fully known. To gain further knowledge and better understanding of the nature of solution species, their specific interaction and participation in the gibbsite crystallization mechanisms, the role alkali ions play in the kinetic behaviour and mechanisms of nucleation, growth and aggregation/agglomeration from caustic aluminate solutions of industrial strength has been investigated.

Gasification of black liquor is an alternative to the combustion of black liquor, which is currently the dominant form of chemical recovery in the paper industry. Gasification of black liquor offers the possibility of higher thermal efficiencies than combustion, reducing manufacturing costs and creating new revenue streams through a forest biorefinery. Pressurizing the gasification reactor further enhances the efficiency advantage of gasification over combustion. This study uses a pressurized entrained flow reactor (PEFR) to study black liquor gasification behavior under pressures, temperatures, and heating rates similar to those of next-generation high-temperature black liquor gasifiers. The effects of pressure on black liquor char morphology, gasification rates, pyrolysis carbon yields, and sulfur phase distribution were studied. These characteristics were investigated in three main groups of experiments at 900oC: pyrolysis (100% N2), gasification with constant partial pressure (0.25 bar H2O and 0.50 bar CO2), and gasification with constant mole fraction (10% CO2, 2% H2O, 1.7% CO, 0.3% H2), under five, ten, and fifteen bar total pressure. It was found that pressure had an impact on the char physical characteristics immediately after the char entered the reactor. Increasing pressure had the effect of decreasing the porosity of the chars. Pressure also affected particle destruction and reagglomeration mechanisms. Surface areas of gasification chars decreased with increasing pressures, but only at low carbon conversions. The rate of carbon conversion in gasification was shown to be a function of the gas composition near the particle, with higher levels of inhibiting gases slowing carbon conversion. The same phenomenon of product gas inhibition observed in gasification was used to explain carbon conversions in pyrolysis reactions. Sulfur distribution between condensed and gas phases was unaffected by increasing total pressure in the residence times investigated. Significant amounts of sulfur are lost during initial devolatilization. With water present this gas phase sulfur forms H2S and did not return to the condensed phase.