Abstract. The content of some metals (Na, K, Ca, Mg, Mn and Li) in a variety of red wines produced in different geographical zones of Galicia was determined in a single analysis by capillary electrophoresis. Data were processed using multivariate supervised and non-supervised chemometric techniques involving cluster analysis, principal component analysis (PCA), linear discriminant analysis (LDA), K nearest neighbours (KNN) and soft independent modelling of class analogy (SIMCA). The results obtained have allowed for the categorisation of wine samples according to their origin; the wines with Ribeira Sacra Certified Brand of Origin (CBO) can be differentiated from the wines of two other CBO from Galicia: Ribeiro and Valdeorras. The latter two types of wine are made with the same or similar grape varieties; hence, due to their similar organoleptic properties they are possible substitutes for the falsification of Ribeira Sacra wines.
A quick technique for determination of kinetic parameters of fermentation processes is proposed and applied to the transformation of D-xylose into ethanol by Pichia stipitis. The commonly used method to evaluate these parameters is based on achieving several steady states. In the proposed procedure, p,,, and KS can be determined from only one steady state, by provoking a disturbance over it, after allowing the system to return to the original conditions. The main difference between the steady and unsteady state methods is the required fermentation time; while the former method lasted 350 h, the latter required a period 25 times lower. Kinetic and stoichiometric parameters were determined with both methods under anoxic and limited oxygen concentration conditions. Results from the two methods were com-
A simple technique is described for the routine simultaneous capillary electrophoretic determination of 6 cations in wine. Separation was achieved on a fused silica capillary column with a UV-Cat-1, α-hydroxysobutyric acid and 18-crown-6-ether buffer at pH 4.5 and indirect UV detection at 214 nm. The content of magnesium, sodium, potassium, calcium, manganese, and lithium was determined. The method is quantitative, with recoveries in the 92–102% range, and linear over more than one order of magnitude. The precision is better than 2.5–3.4%. The method is sensible, with detection limits between 0.01 and 0.06 mg/L. Twenty-five red wines with a Certified Brand of Origin from Galicia (northwestern Spain) were analyzed by the proposed method. Various wines showed very similar electrophoretic profiles, but significant quantitative differences were observed.
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