Browsing by Author "Corzo, Nieves"
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- Improving Properties of a Novel β-Galactosidase from Lactobacillus plantarum by Covalent ImmobilizationPublication . Benavente, Rocio; Pessela, Benevides C.; Curiel, Jose Antonio; de las Rivas, Blanca; Muñoz, Rosario; Guisán, Jose Manuel; Mancheño, Jose M.; Cardelle-Cobas, Alejandra; Ruiz-Matute, Ana I.; Corzo, NievesA novel -galactosidase from Lactobacillus plantarum (LPG) was over-expressed in E. coli and purified via a single chromatographic step by using lowly activated IMAC (immobilized metal for affinity chromatography) supports. The pure enzyme exhibited a high hydrolytic activity of 491 IU/mL towards o-nitrophenyl -d-galactopyranoside. This value was conserved in the presence of different divalent cations and was quite resistant to the inhibition effects of different carbohydrates. The pure multimeric enzyme was stabilized by multipoint and multisubunit covalent attachment on glyoxyl-agarose. The glyoxyl-LPG immobilized preparation was over 20-fold more stable than the soluble enzyme or the one-point CNBr-LPG immobilized preparation at 50 degrees C. This -galactosidase was successfully used in the hydrolysis of lactose and lactulose and formation of different oligosaccharides was detected. High production of galacto-oligosaccharides (35%) and oligosaccharides derived from lactulose (30%) was found and, for the first time, a new oligosaccharide derived from lactulose, tentatively identified as 3'-galactosyl lactulose, has been described.
- Obtention of prebiotic oligosaccharides derived from lactulose using Kluyveromyces marxianus crude cell extractsPublication . Corzo, Nieves; Padilla, Beatriz; Belloch, Carmela; Cardelle-Cobas, Alejandra; Manzanares, Paloma; Matute, Ana I. Ruiz
- Study of Functional properties of chitosan-lactose derivatives obtained by Maillard reactionPublication . Ruiz-Matute, Ana I.; García-Bermejo, Ana B.; Cardelle-Cobas, Alejandra; Olano, Agusín; Corzo, Nieves
- Synthesis, characterization and functional properties of galactosylated derivatives of chitosan through amide formationPublication . Matute, Ana I. Ruiz; Cardelle-Cobas, Alejandra; García-Bermejo, Ana B.; Montilla, Antonia; Olano, Agustin; Corzo, NievesLow molecular weight chitosan (LMWC) and chitooligosaccharide (COS) derivatives were obtained by the introduction of lactobionic acid (LA) through amide formation, obtaining different complexes COS-LA and LMWC-LA (1-5), with a degree of substitution (DS) between 3 and 16%. The synthesis of these derivatives was monitored by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), High-Performance Liquid Chromatography-Size Exclusion Chromatography (HPLC-SEC) and proton Nuclear Magnetic Resonance (1H NMR) analyses. Different functional properties, solubility, water binding capacity (WBC) and fat binding capacity (FBC), as well as the antioxidant activity (DPPH radical scavenging activity) of these derivatives were evaluated. Solubility, WBC and FBC increased in all of the chitosan derivatives respect to those of the native LMWC or COS. The most substituted derivative (LMWC-LA1, DS 15%) presented the highest value of solubility (14.4mg/mL) while the highest levels of WBC and FBC were obtained for the derivative with a DS of 3% (LMWC-LA5; 4730% and 7100%, respectively). COS and COS-LA presented the best DPPH scavenging abilities, as shown by their low values of EC50 (1.29 and 3.45mg/mL, respectively). An inverse relationship between the DS of chitosan derivatives and antioxidant activity was observed. LMWC-LA5 (3% DS) was the derivative with the highest DPPH activity, being higher than LMWC in all the concentrations assayed (10.2-14.3% and 6.9-13.7%, respectively). Due to their enhanced functional properties, these chitosan derivatives could be considered as very promising for their future use as additives in the food industry (i.e. to bind fat and cholesterol or avoid hardening of foods).
- Synthesis, optimization and structural characterization of a chitosan-glucose derivative obtained by the Maillard reactionPublication . Gullón, Beatriz; Montenegro, María I.; Ruiz-Matute, Ana I.; Cardelle-Cobas, Alejandra; Corzo, Nieves; Pintado, Manuela E.Chitosan (Chit) was submitted to the Maillard reaction (MR) by co-heating a solution with glucose (Glc). Different reaction conditions as temperature (40, 60 and 80 °C), Glc concentration (0.5%, 1%, and 2%, w/v), and reaction time (72, 52 and 24h) were evaluated. Assessment of the reaction extent was monitored by measuring changes in UV absorbance, browning and fluorescence. Under the best conditions, 2% (w/v) of Chit, 2% (w/v) of Glc at 60°C and 32 h of reaction time, a chitosan-glucose (Chit-Glc) derivative was purified and submitted to structural characterization to confirm its formation. Analysis of its molecular weight (MW) and the degree of substitution (DS) was carried out by HPLC-Size Exclusion Chromatography (SEC) and a colloid titration method, respectively. FT-IR and (1)H NMR were also used to analyze the functional groups and evaluate the introduction of Glc into the Chit molecule. According to our objectives, the results obtained in this work allowed to better understand the key parameters influencing the MR with Chit as well as to confirm the successful introduction of Glc into the Chit molecule obtaining a Chit-Glc derivative with a DS of 64.76 ± 4.40% and a MW of 210.37 kDa.