Examinando por Autor "Giraldo-Estrada, C."
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Ítem Biodegradation of vegetable residues by polygalacturonase-agar using a trickle-bed bioreactor(Institution of Chemical Engineers, 2018-09-01) Ramírez-Tapias, Y.A.; Rivero, C.W.; Giraldo-Estrada, C.; Britos, C.N.; Trelles, J.A.; Universidad EAFIT. Departamento de Ciencias; Ciencias Biológicas y Bioprocesos (CIBIOP)Bacterial pectinases degrade the pectic substances present in plant tissues and particularly, polygalacturonases catalyze the hydrolysis of a-(1,4) glycosidic bonds linking D-galacturonic acid units. In this study, polygalacturonase from Streptomyces halstedii ATCC 10897 was immobilized by the matrix entrapment technique using different thermogels. Bacteriological agar added with magnesium cation produced beads with a more stabilized microstructure for enzyme retention, monitored by oscillatory measurements of storage and loss modulus. Agar concentration and protein content were optimized to maximize protein entrapment, product conversion, and reaction yield. Results showed that the mixture at 10:90% (v/v) of protein (2 mg/mL) and agar (4% w/v) was the best immobilization condition to retain 91% of protein and hydrolyze 38% of pectin to allow the highest reaction yield (9.279 g/g) and increase stability up to 48 h of successive reactions. Agarose bead biocatalysts were used in a trickle-bed column operated with recirculation, and this bioreactor allowed the degradation of pear and cucumber residues by enzymatic liquefaction to enhance sugar content up to 15.33 and 9.35 mg/mL, respectively, and decrease viscosity by 92.3%. The scale-up of this process adds value to vegetable residues such as fructooligosaccharides or fermentable sugars, which become a sustainable source of fuels and chemicals. © 2018 Institution of Chemical EngineersÍtem Evaluation of biological production of lactic acid in a synthetic medium and in Aloe vera (L.) Burm. f. processing by-products(Pontificia Universidad Javeriana, 2015-01-01) Gómez-Gómez, J.A.; Giraldo-Estrada, C.; Habeych, D.; Baena, S.; Universidad EAFIT. Departamento de Ciencias; Ciencias Biológicas y Bioprocesos (CIBIOP)This study evaluated lactic acid production through batch fermentation in a bioreactor with Thermoanaerobacter sp. strain USBA-018 and a chemically defined culture medium and with hydrolyzed pressed extract of Aloe vera peel (AHE). The strain USBA-018 fermented various sugars, but its primary end-product was L-lactic acid. Factors which influenced L- lactic acid production were pH, addition of yeast extract (YE) and manganese chloride. Under the most favorable growing conditions for the production of lactic acid, yield (Yp/s) increased from 0.66 to 0.96 g/g with a productivity (Qp) of 0.62 g.l-1.h and a maximum lactic acid concentration of 178 mM at 26 hours of fermentation. When AHE was used, 93.3 mM, or 0.175 g.l-1.h, was obtained. These results show the potential for transformation of sugars that strain USBA-018 offers, but additional studies are needed to find out if different strategies using AHE as carbon source can produce large enough quantities of lactic acid to allow AHE to become a low-cost alternative substrate.Ítem Supercritical CO2 extraction of oil and omega-3 concentrate from Sacha inchi (Plukenetia volubilis L.) from Antioquia, Colombia(Instituto de la Grasa, 2017-01-01) Triana-Maldonado, D.M.; Torijano-Gutiérrez, S.A.; Giraldo-Estrada, C.; Universidad EAFIT. Departamento de Ciencias; Ciencias Biológicas y Bioprocesos (CIBIOP)Sacha inchi (Plukenetia volubilis L.) seeds were employed for oil extraction with supercritical CO2 at laboratory scale. The supercritical extraction was carried out at a temperature of 60 °C, pressure range of 400-500 bars and CO2 flow of 40-80 g/min. The maximum recovery was 58% in 180 min, favored by increasing the residence time of CO2 in the extraction tank. Subsequently, the process was evaluated at pilot scale reaching a maximum recovery of 60% in 105 min, with a temperature of 60 °C, pressure of 450 bars and CO2 flow of 1270 g/min. The fatty acid composition of the oil was not affected for an extraction period of 30-120 min. The Sacha inchi oil was fractionated with supercritical CO2 to obtain an omega-3 concentrate oil without finding a considerable increase in the proportion of this compound, due to the narrow range in the carbon number of fatty acids present in the oil (16-18 carbons), making it difficult for selective separation. © 2017 CSIC.