Browsing by Subject "Enzymes"

Now showing 1 - 7 of 7
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    Biocatalytic synthesis of polymeric esters used as emulsifiers
    (Croatian Society of Chemical Engineers, 2019) Ortega Requena, Salvadora; Serrano-Arnaldos, M.; Montiel Morte, María Claudia; Máximo, María Fuensanta; Bastida Rodríguez, Josefa; Murcia Almagro, María Dolores; Ingeniería Química
    Polyglycerol polyricinoleate (PGPR) is a polymeric ester widely used as emulsifier in the food industry. In this work, PGPR biocatalytic synthesis was carried out in a onestep solvent-free enzymatic process using lipase CALB immobilized in Lewatit® Monoplus MP 64 by adsorption. The optimal immobilization conditions were determined: initial enzyme concentration of 13 mg of Lowry protein per mL phosphate buffer pH 7, and ricinoleic acid as a support activator. An immobilized derivative with 35.93 ± 4.90 mg of Lowry protein per g of dry support was obtained. It was used as a catalyst for PGPR production in open air and vacuum batch reactors, and the results obtained showed that only when the reaction equilibrium was shifted towards ester production by means of water removal, the PGPR produced fulfilled the European legislation (acid value ≤ 6 mg of KOH per g of product).
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    Combining high-power ultrasound and enological enzymes during winemaking to improve the chromatic characteristics of red wine
    (Elsevier, 2021-12-28) Pérez Porras, Paula; Bautista Ortín, Ana Belén; Jurado, Ricardo; Gómez Plaza, Encarna; Tecnología de Alimentos, Nutrición y Bromatología; Facultad de Veterinaria
    Several techniques have been used by the winemaking industry to facilitate the extraction of grape phenolic compounds during the maceration process. Interest in innovative techniques such as high-power ultrasound (US) has increased in recent years, replacing more traditional techniques such as the addition of pectolytic enzymes (E). This study evaluates the combined effect of ultrasound and enological enzymes, used at semi-industrial scale at the time of crushing, on the chromatic characteristics of red wine. Variables such as the timing of enzyme addition and the ripening state of the grapes were considered. The results showed that ultrasound had a greater effect than enological enzymes when used alone, especially when the ripest grapes were used. The results also indicate that, when added after sonication, the enzymes favored the US effect, enabling the contact time necessary to achieve a wine with chromatic characteristics similar to those resulting from a traditional maceration process to be reduced by 4 days. Carried out on a semi-industrial scale, the study demonstrates that the adequate combination of these two techniques can optimize the maceration process both in terms of time and the wine organoleptic characteristics, making the technique of special interest for industrial application.
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    Effects of combining high power ultrasound and enological enzymes on the composition of polysaccharides in red wine
    (Elsevier, 2022-10-04) Martínez-Lapuente, Leticia; Guadalupe, Zenaida; Ayestarán, Belén; Pérez Porras, Paula; Bautista Ortín, Ana Belén; Gómez Plaza, Encarna; Tecnología de Alimentos, Nutrición y Bromatología; Facultad de Veterinaria
    In this work different oenological techniques, used at semi-industrial scale, were applied for their effect of deconstructing the polysaccharide network of the cells of the grape during the maceration: high-power ultrasound (US), a new technique recently introduced in the wine industry, and other conventional ones, such as the addition of pectolytic enzymes (E). The objective was to study if the combined effect of US and E, used at the moment of crushing, had a synergistic effect on the content of polysaccharides in red wines, compared to red wines made with the techniques applied separately. The timing of enzyme addition, maceration time and the ripening state of the grapes were the studied variables. Ultrasound treatment showed a greater effect than enological enzymes when used alone, especially when the ripest grapes were employed. The results also indicated that the combined treatment, regardless of the order of enzyme addition, did not improve the release of grape polysaccharides into the wine. Sonication maintained the same profile of polysaccharides than the control wine. The study demonstrated that sonication treatment increased the content of polysaccharides from the grapes into the wines, allowing a reduction of the maceration time.
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    Enzyme histochemistry of corneal wound healing
    (Murcia : F. Hernández, 1998) Cejkova, J.
    The usefulness of enzyme histochemical methods for the localization of enzymes as catalysts of molecular interactions in the cells and tissues of healing corneal wounds is shown in rabbits. The current data on corneal wound healing in humans as well as in rabbits with particular reference to serine proteases are reviewed. Some inflammatory mediators are also discussed. Plasmin is a serine protease which is absent (or present only in very low concentration) in the tear fluid, and its activity appears under various pathological conditions in humans or following experimental injuries in rabbits. The role of increasing plasmin activity in the tear fluid in the depending upon the severity of corneal injury is evaluated. Great attention is devoted to conditions leading to long-lasting elevated levels of plasmin activity in the tear fluid correlated with corneal ulceration. The differences between the histochemical pattern of untreated corneas or corneas treated with some serine protease inhibitors are shown, and the efficacy of these drugs is discussed in light of present knowledge.
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    Mercury accumulation, structural damages, and antioxidant and immune status changes in the Gilthead Seabream (Sparus aurata L.) exposed to methylmercury
    (Springer, 2016-02-23) Chaves-Pozo, E.; Espinosa, C.; Romero, D.; Meseguer, J.; Cuesta Peñafiel, Alberto; Esteban Abad, María de los Ángeles; Guardiola Abellán, Francisco Antonio; Ciencias Sociosanitarias
    In aquatic systems, mercury (Hg) is an environmental contaminant that causes acute and chronic damage to multiple organs. In fish, practically all of the organic Hg found is in the form of methylmercury (MeHg), which has been associated with animal and human health problems. This study evaluates the impact of waterborne-exposure to sublethal concentrations of MeHg (10 [mu]g L^sup -1^) in gilthead seabream (Sparus aurata). Hg was seen to accumulate in liver and muscle, and histopathological damage to skin and liver was detected. Fish exposed to MeHg showed a decreased biological antioxidant potential and increased levels of the reactive oxygen molecules compared with the values found in control fish (nonexposed). Increased liver antioxidant enzyme activities (superoxide dismutase and catalase) were detected in 2 day-exposed fish with respect to the values of control fish. However, fish exposed to MeHg for 10 days showed liver antioxidant enzyme levels similar to those of the control fish but had increased hepato-somatic index and histopathological alterations in liver and skin. Serum complement levels were higher in fish exposed to MeHg for 30 days than in control fish. Moreover, head-kidney leukocyte activities increased, although only phagocytosis and peroxidase activities showed a significant increase after 10 and 30 days, respectively. The data show that 30 days of exposure to waterborne MeHg provokes more significant changes in fish than a short-term exposure of 2 or 10 days.
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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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    The production and application of enzymes related to the quality of fruit wine
    (Taylor and Francis, 2020-05-19) Yang, Hua; Lu, Jian; Gómez Plaza, Encarna; Tecnología de Alimentos, Nutrición y Bromatología; Facultad de Veterinaria
    Grape wine is the most widely consumed fruit wine in the world. With the increasing diversification of consumers' needs, the variety of fruit wines in the market is becoming more and more abundant. Whether it is the production of grape wine or other fruit wines these processes are inseparable from the participation of enzymes. The quality of these wines is closely related to the application of enzymes in the winemaking process. Enzymes are involved in pre-treatment, fermentation, filtration, flavoring, aging and storage of fruit wines. This review systematically illustrated the role of pectinase, β-glucanase, β-glucosidase, lysozyme, glucose oxidase, lysozyme, protease, tannase, urease, in the production of wines and their current production status and also provided a theoretical basis for better application of various enzymes in the production of various fruit wines. This knowledge could be great significance to improve the quality of fruit wines and reduce the production costs in the fruit wine industry.