RESUMO
High pressure processing (HPP) technology was used to modify the structural composition of sugarcane bagasse. The effect of pressure (0, 150 and 250 MPa), time (5 and 10 min) and temperature (25 and 50 °C) as well as the addition of phosphoric acid, sulfuric acid and NaOH during the HPP treatment were assessed in terms of compositional analysis of the lignocellulosic fraction, structural changes and crystallinity of the bagasse. The effect of HPP pretreatment on the bagasse structure was also evaluated on the efficiency of the enzymatic hydrolysis of bagasse. Results showed that 68.62 and 45.84% of the hemicellulose fraction was degraded by pretreating at 250 MPa with sulfuric and phosphoric acids, respectively. The removal of lignin (54.10%) was higher with the HPP-NaOH treatment. The compacted lignocellulosic structure of the raw bagasse was modified by the HPP treatments and showed few cracks, tiny holes and some fragments flaked off from the surface. Structural changes were higher at 250 MPa and 50 °C. The X ray diffraction (XRD) patterns of the raw bagasse showed a major diffraction peak of the cellulose crystallographic 2θ planes ranging between 22 and 23°. The distribution of the crystalline structure of cellulose was affected by increasing the pressure level. The HPP treatment combined with NaOH 2% led to the higher glucose yield (25 g/L) compared to the combination of HPP with water and acids (>5 g/L). Results from this work suggest that HPP technology may be used to pretreat sugarcane bagasse.
Assuntos
Celulose/química , Pressão , Saccharum/química , Celulase/metabolismo , Celulose/metabolismo , Hidrólise , Lignina/química , TemperaturaRESUMO
Molasses "B" is a rich co-product of the sugarcane process. It is obtained from the second step of crystallization and is richer in fermentable sugars (50-65%) than the final molasses, with a lower non-sugar solid content (18-33%); this co-product also contains good vitamin and mineral levels. The use of molasses "B" for ethanol production could be a good option for the sugarcane industry when cane sugar prices diminish in the market. In a complex medium like molasses, osmotolerance is a desirable characteristic for ethanol producing strains. The aim of this work was to evaluate the use of molasses "B" for ethanol production using Saccharomyces cerevisiae ITV-01 (a wild-type yeast isolated from sugarcane molasses) using different initial sugar concentrations (70-291 g L(-1)), two inoculum sizes and the addition of nutrients such as yeast extract, urea, and ammonium sulphate to the culture medium. The results obtained showed that the strain was able to grow at 291 g L(-1) total sugars in molasses "B" medium; the addition of nutrients to the culture medium did not produce a statistically significant difference. This yeast exhibits high osmotolerance in this medium, producing high ethanol yields (0.41 g g(-1)). The best conditions for ethanol production were 220 g L(-1) initial total sugars in molasses "B" medium, pH 5.5, using an inoculum size of 6 × 10(6) cell mL(-1); ethanol production was 85 g L(-1), productivity 3.8 g L(-1 )h(-1) with 90% preserved cell viability.
Assuntos
Reatores Biológicos/microbiologia , Etanol/metabolismo , Melaço/microbiologia , Saccharomyces cerevisiae/metabolismo , Saccharum/metabolismo , Saccharum/microbiologia , Proliferação de Células , Sobrevivência Celular , Etanol/isolamento & purificaçãoRESUMO
Immunoglobulin Y (IgY) was purified from hen egg yolk water-soluble protein fraction by ultrafiltration-diafiltration with different membranes. The effect of changing solution properties (pH and ionic strength) on purification factor (P), process selectivity (Psi), and IgY recovery (RIgY) was studied. Salt presence (150 and 1500 mM) decreased the selectivity and purity factor. This effect was more evident at pH values closer to or higher than the IgY's isoelectric point. The best results were obtained in the absence of salt at pH values of 5.7 and 6.7 using poliethersulfone (PES) and modified PES (MPES), respectively. Process selectivity was doubled, and IgY's purification factors were increased in more than 1 order of magnitude when diafiltration was used. Results from this work show the potential of membrane technology for the purification of IgY from hen's egg yolk.