Browsing by Subject "Chromatography"

Now showing 1 - 5 of 5
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    Determination of beet root betanin in dairy products by High-Performance Liquid Chromatography (HPLC)
    (American Chemical Society, 2012-03-23) Simón-Carrillo, Ana; Escribano Cebrián, Josefa; Gandía Herrero, Fernando; García Carmona, Francisco; Departamentode Bioquímica y Biología Molecular "A"
    The food industry uses different additives to give foods and beverages the appearance expected by the consumer. Among them, pigments of natural origin are receiving increasing attention due to safety concerns about traditional colorants and the relevance of a healthy diet. This experiment describes the quantitative determination of the characteristic pigment of red beet roots in dairy foods such as conventional yogurt, drinking yogurt, and fromage frais of strawberry, blackberry, and apricot varieties. The laboratory experiment is suitable for an undergraduate instrument analysis course and introduces the principles involved in chromatographic techniques and the use of high-performance liquid chromatography (HPLC) equipment. It also opens the discussion to other concepts such as carbon chirality, absorbance, and the requirements of food additives.
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    Optimized enzymatic synthesis of the food additive polyglycerol polyricinoleate (PGPR) using Novozym® 435 in a solvent free system
    (Elsevier, 2014-01-21) Ortega Requena, Salvadora; Bódalo-Santoyo, A.; Bastida Rodríguez, Josefa; Máximo, María Fuensanta; Montiel Morte, María Claudia; Gómez Gómez, María; Ingeniería Química; Facultad de Química
    Polyglycerol polyricinoleate (PGPR) is used as an emulsifier in the food industry, especially in chocolate coatings and chocolate bars. PGPR improves the characteristics of molten chocolate by reducing yield stress, facilitating the coating of confectionery pieces, while limiting the amount of cocoa butter involved. The enzymatic synthesis of PGPR catalyzed by lipases presents several advantages over chemical synthesis, including enzyme specificity and the mild conditions needed, thereby avoiding undesirable side-reactions and by-products. A novel process to synthesize PGPR using a biocatalyst, Novozym® 435, is presented. Novozym® 435 is appropriate for catalyzing both the reactions involved in this process. A PGPR fulfilling European specifications for this food additive as well as recommendations set out in the Food Chemical Codex, was obtained using a discontinuous vacuum reactor with a dry nitrogen flow. In addition, the biocatalyst reuse would decrease costs. Moreover, it was confirmed that the ability to obtain PGPR in a one-step reaction significantly shortens the time required.
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    Size-exclusion chromatography of macromolecules: a brief tutorial overview on fundamentals with computational tools for data analysis and determination of structural information
    (MDPI, 2025-02-22) Henández-Cifre, José Ginés; Collado-González, Mar; Díaz Baños, F. Guillermo; García de la Torre, José; Química Física; Ingeniería Química; Biología Celular e Histología
    Size-exclusion chromatography (SEC) is presently a widely used and very informative technique for the characterization of macromolecules in solution. Beyond the first implementations of SEC—which required cumbersome column calibrations and were mainly intended for the determination of molecular weights—the modern SEC approach involving multiple detectors (md-SEC) is based on solution properties such as intrinsic viscosity and light scattering. Thus, md-SEC enables the direct and more efficient determination of molecular weights, as well as the determination of relationships between property and molecular weight, which can be quite useful in structural studies. Here, we first present a review of the fundamental aspects of the dilute-solution properties of macromolecules—particularly the differential refractive index, intrinsic viscosity, and scattering-related properties—on which the various detectors involved in md-SEC are based. Then, we developed SECtools, a suite of public-domain, open-source computer programs, which allow for the full analysis of md-SEC chromatograms. These analyses range from just the recorded raw signals (mV) of the detectors to a full determination of molecular weight averages and distributions. The use of these programs is illustrated through experimental studies using various samples.
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    Structural characterization of mesquite (Prosopis velutina) gum and its fractions
    (Wiley, 2008-07-31) López Franco, Yolanda L.; Calderón de la Barca, Ana María; Valdez, Miguel Ángel; Peter, Martin G.; Rinaudo, Marguerite; Chambat, Gérard; Goycoolea Valencia, Francisco Martín; Biología Celular e Histología; Facultades de la UMU::Facultad de Biología
    Structural and physicochemical characteristics of mesquite gum (from Prosopis velutina) were investigated using FT-IR spectroscopic, mass spectrometric and chromatographic methods. Four fractions (F-I, F-IIa, F-IIb and F-III) were isolated by hydrophobic interaction chromatography. The samples were characterized and analyzed for their monosaccharide and oligomers composition by high performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). L-Arabinose (L-Ara) and D-galactose (D-Gal) were found as the main carbohydrate constituent residues in the polysaccharides from mesquite gum and their ratio (L-Ara/D-Gal) varied within the range 2.54 to 3.06 among the various fractions. Small amounts of D-glucose (D-Glc), D-mannose (D-Man) and D-xylose (D-Xyl) were also detected, particularly in Fractions IIa, IIb and III. Infrared spectroscopy identified polysaccharides and protein in all the samples. Data from mass spectrometry (MALDI-TOF MS) was consistent with the idea that the structure corresponding to the periphereal chains of Fraction I is predominantly a chain of pentoses attached to uronic acid.
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    Study of the effect of sample pressure on in situ BTEX chromatographs
    (Springer, 2016-11-12) Romero Trigueros, Cristina; Doval Miñarro, Marta; González Duperón, Esther; Marzal Martínez, Francisco José; González Ferradás, Enrique; Ingeniería Química
    In this paper, the influence of sample pressure on benzene measurements obtained with two automated in situ gas chromatographs is studied. The analysers were calibrated using a non-linear regression at 293 ± 1 K and 101.3 ± 0.2 kPa. A gas mixture of benzene in air (5 μg/m3) was produced and measured at calibration conditions. Subsequently, the sample pressure was changed to 80 and 110 kPa. Differences in readings were observed even though the pressure compensators were on, indicating incorrect performance of this tool. Further tests with two different benzene in air mixtures (5 and 40 μg/m3) at 80, 90, 105 and 110 kPa were also carried out. Results showed that the analysers take air from one or several unidentified inlets (apart from the sampling port) when the sampling pressure is lower than the atmospheric one. This is usually the case in air monitoring stations, so this phenomenon is particularly important as systematic biases could be affecting air quality data.