Neste estudo foi desenvolvida uma metodologia para autenticação de azeites de oliva extra virgem com diferentes níveis de acidez através da espectroscopia na região do Ultravioleta e Visível (UV-Vis) acoplada ao método de Mínimos Quadrados Parciais com Análise Discriminante (PLS-DA). A sensibilidade do modelo foi igual a 1.0. Com base nesse resultado, o modelo foi capaz de classificar corretamente todas as amostras de azeite de oliva de acordo com seus diferentes níveis de acidez. A especificidade também apresentou resultado igual a 1.0, o que significa que nenhuma amostra foi classificada de forma errônea em uma outra classe. A habilidade da espectroscopia UV-Vis na autenticação dos azeites de oliva extra virgem baseado em seus diferentes níveis de acidez pode ser atribuída aos deslocamentos hipocrômico e hipercrômico, devido às absorções entre 250 – 510 nm e 670 nm, que são características de carotenos e clorofilas.
<p>The objective of this study was to chemically modify the pregelatinized cassava starch to obtain resistant starches to the action of α-amylase present in the egg and evaluate their application in cold cheese bread dough. In this study native cassava starch was cross-linked with sodium trimetaphosphate in a concentration of 0.5% (d.b.). The cross-linked starch was oxidized with sodium hypochlorite (2.0%), hydrogen peroxide (2.0%) and combinations of hydrogen peroxide with potassium permanganate (0.1%), ferrous sulfate (0.05%) and ozone (1.0 g/h). All oxidations occurred during a period of 2 hours at room temperature. The modified starches were pregelatinized for 30 minutes at 95 ° C and spray dried. The solubility index and water absorption, content of carboxyl groups and the enzymatic susceptibility to α-amylase of the modified starches were evaluated. Cheese bread dough was prepared with pregelatinized modified starch and stored under refrigeration (8 °C) for sixteen days. The tackiness index of the dough, which represents its stability during refrigerated storage, and physical characteristics of the cheese breads were evaluated. The starches studied exhibited lower susceptibility to enzymatic hydrolysis. During refrigerated storage, doughs showed a lower rate of tackiness, good consistency and the cheese breads exhibited good appearance, however they had lower specific volume and rate of expansion. The results of the study show that the characteristics of the modified starch during the storage period, promoted better product stability.</p><p> </p><p>DOI: http://dx.doi.org/10.14685/rebrapa.v4i2.124</p>
<p>The objective of this study was to esterification cassava starch with stearic acid, to obtain starches with emulsifying properties, stabilizing and encapsulant of oleic acid. The cassava starch was treated with stearic acid in an alkaline medium (pH 8.0, 9.0, 11.0 and 13.0) and catalyzed by microwave radiation, to obtain the saturated ester starch. The percentage of esterification and degree of substitution (DS), the swelling power and solubility, the apparent viscosity of gels, emulsifying activity and the stability of the emulsions prepared with the modified starches were determined. The use of modified starch in the encapsulation of oleic acid and salad dressings was assessed. The pH of the reaction influences the content and esterification in the GS, only sample evaluated at pH 13.0 showed no percentage esterification. The modification reduced apparent viscosity, the swelling power and the solubility of the granules. Esterification at pH 8.0, 9.0 and 11.0 increased the emulsifying stability and encapsulation efficiency of the starches. Could not find correlation between encapsulation efficiency and the hydrophobicity of the starches. The application of modified starch in sauces like mayonnaise for salads did not show favorable results since the emulsion formed was not stabilized. The emulsion stability was compromised due to low viscosity of the starches after modification</p>
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