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Estabilização de Flavonóides Lábeis por imobilização em matrizes sólidas
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| 3.38 MB | Adobe PDF |
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Abstract(s)
As antocianinas são uma classe de pigmentos naturais cuja utilização é interessante enquanto alternativa aos corantes artificiais. Estas moléculas degradam-se facilmente sendo necessário estabilizá-las para que possam ser incluídas em produtos comerciais. A adsorção em matrizes sólidas porosas é uma possível forma de estabilização. A variação da cor é um indicador importante na avaliação da qualidade nas indústrias alimentar e cosmética e é monitorizada por espectrofotometria UV-Vis em líquidos ou por métodos colorimétricos de reflectância em sólidos. Este trabalho avalia a imobilização de antocianinas extraídas a partir de fontes naturais em cinco matrizes sólidas. Extractos ricos em antocianinas foram obtidos a partir de bagas de Myrica faya, Rubus grandifolia e Vaccinium cylindraceum e foram imobilizados em 5 adsorventes: 3 argilas, talco farmacêutico e resina sintética nãofuncionalizada Lewatit. A eficácia de adsorção foi medida por quantificação espectrofotometrica UV-Vis da antocianina em solução antes e após contacto com o adsorvente. A estabilidade dos complexos antocianina/adsorvente expostos a condições de radiação e temperatura elevada foi avaliada por métodos colorimétricos (CIELab). Os extractos de Myrica faya e Rubus grandifolia apresentaram apenas glucosídeos de cianidina enquanto os extractos de Vaccinium cylindraceum continham 10 conjugados glicosídicos de delfinidina, cianidina, petunidina, malvidina e ponidina. Os parâmetros de adsorção foram optimizados: concentração de solução de extracto de antocianina 5g/L, tempo de adsorção 20 minutos, pH 4,3, temperatura ambiente. Os complexos foram submetidos a processos de degradação acelerada e a estabilidade foi avaliada pelas variações colorimétricas traduzidas por parâmetros CIELAB. Os resultados são apresentados em valores de L*, a* e b* e em swacthes de cor obtidos pelo software Adobe Photoshop. A quantidade de antocianina adsorvida no equilíbrio de adsorção variou entre 2 a 43 mg de antocianina por grama de adsorvente; a resina Lewatit foi o melhor adsorvente e o talco o pior. As 3 argilas mostraram resultados idênticos de cerca de 20 mg/g. A resina que adsorve mais quantidade corresponde ao complex menos estável. As argilas provaram ser os adsorventes mais adequados.
Anthocyanins are a class of natural pigments that are interesting alternatives to artificial colorants. They degrade easily, so they need to be stabilized to be include in commercial products. Adsorption into porous solids is a possible form of stabilization. Color variation is an important indicator of quality assessment in food and cosmetics industries and it is monitorized by UV/Vis spectroscopy in liquids or by reflectance colorimetric methods in solids. This work, evaluates the immobilization of anthocyanins into five solid matrices. Anthocyanin rich extracts were obtained from Myrica faya, Rubus grandifolia and Vaccinium cylindraceum berries and were immobilized on 5 sorbents: 3 clays, 1 talc and 1 synthetic resin (non-functionalized Lewatit). Adsorption efficiency was measured by UV-Vis quantification of anthocyanin in solution before and after contact with adsorbent. The stability of anthocyanin / adsorbent complexes exposed to radiation conditions and temperature was evaluated by colorimetric methods (CIELab). Myrica faya e Rubus grandifolia showed only cyanidin glucosides while Vaccinium cylindraceum presented 10 glucoside conjugates of delfinidin, cyanidin, petunidin, malvidin and peonidin. Adsorption parameters were optimized: initial anthocyanin extract solution concentration 5g/L, time of contact 20 minutes, pH 4,3, at room temperature. Complexes were submitted to processes of accelerated degradation and stability was evaluated by color variations, as CIELAB parameters. Results are presented as L*, a* and b* and as color swatches using Adobe Photoshop software. Adsorption at equilibrium ranged from 2 to 43 mg of anthocyanin/g of adsorbent, the best the resin and the worst the talk. The 3 clays showed similar results, about 20 mg/g. The resin, which adsorbs the highest quantity, forms the least stable complex. Clays proved to be the most adequate adsorbents.
Anthocyanins are a class of natural pigments that are interesting alternatives to artificial colorants. They degrade easily, so they need to be stabilized to be include in commercial products. Adsorption into porous solids is a possible form of stabilization. Color variation is an important indicator of quality assessment in food and cosmetics industries and it is monitorized by UV/Vis spectroscopy in liquids or by reflectance colorimetric methods in solids. This work, evaluates the immobilization of anthocyanins into five solid matrices. Anthocyanin rich extracts were obtained from Myrica faya, Rubus grandifolia and Vaccinium cylindraceum berries and were immobilized on 5 sorbents: 3 clays, 1 talc and 1 synthetic resin (non-functionalized Lewatit). Adsorption efficiency was measured by UV-Vis quantification of anthocyanin in solution before and after contact with adsorbent. The stability of anthocyanin / adsorbent complexes exposed to radiation conditions and temperature was evaluated by colorimetric methods (CIELab). Myrica faya e Rubus grandifolia showed only cyanidin glucosides while Vaccinium cylindraceum presented 10 glucoside conjugates of delfinidin, cyanidin, petunidin, malvidin and peonidin. Adsorption parameters were optimized: initial anthocyanin extract solution concentration 5g/L, time of contact 20 minutes, pH 4,3, at room temperature. Complexes were submitted to processes of accelerated degradation and stability was evaluated by color variations, as CIELAB parameters. Results are presented as L*, a* and b* and as color swatches using Adobe Photoshop software. Adsorption at equilibrium ranged from 2 to 43 mg of anthocyanin/g of adsorbent, the best the resin and the worst the talk. The 3 clays showed similar results, about 20 mg/g. The resin, which adsorbs the highest quantity, forms the least stable complex. Clays proved to be the most adequate adsorbents.
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Keywords
Antocianinas Estabilidade Adsorção Argilas CIELab Bagas vermelhas Anthocyanins Stability Adsorption Clays Red berries Bioquímica Aplicada . Faculdade de Ciências Exatas e da Engenharia