HPLC Analysis of Carbohydrates in Wines and Instant Coffees Using Anion Exchange Chromatography Coupled to Pulsed Amperometric Detection
ABSTRACT Carbohydrates (arabinose, fructose, fucose, galactose, glucose, mannose, rhamnose, ribose, sucrose, xylose, and the alditol mannitol) have been analyzed in wines and instant coffees, using anion exchange chromatography coupled to pulsed amperometric detection. Good separation and resolution of the 11 compounds were obtained using just nanopure water as eluent, although rinsing the column with 0.2 M NaOH was necessary to avoid gradual decline in column resolution. Coffee solution, red wines, and rose wines needed a cleanup process by solid-phase extraction on C18 cartridges. Arabinose, galactose, glucose, xylose, mannose, fructose, and ribose were detected and quantified in red wines using melezitose as internal standard. In the case of the coffee samples mannitol, fucose, arabinose, rhamnose, galactose, glucose, sucrose, mannose, and fructose were quantified and differences between unadulterated and adulterated coffees could be detected. Keywords: Pulsed amperometric detection; HPLC; carbohydrates; wines; coffees
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ABSTRACT: Coffee as high-price commodity is quite vulnerable to adulteration by cheaper roasted grains. Frauds are conventionally detected by microscopy; however, this technique is limited semi-quantitative assays that require training and skilled analysts. In this regard, carbohydrates as major macronutrients of grains can be used as chemical markers to qualitatively and quantitatively assess coffee authenticity. Although, some tamper´s studies have already been reported, this paper approaches on new analytical resources for detection of ground roasted coffee adulteration, applying roasted soybean and wheat as sources of fraud. The characterization of the pure roasted coffee beans and of adulterations profiles was taken by total carbohydrates validated method based on high-performance anion-exchange chromatography with pulsed amperometric detection. The influence of each matrix was evaluated employing the simplex-centroid design for experiments with mixtures thus relating the mixing ratio with each monosaccharide by response surface. The proposed models were effective in recognition and prediction of different mixture proportions, thereby allowing the distinction of genuine coffee by principal component analysis and linear discriminant analysis. Predominantly, pure roasted coffee presented higher levels of galactose and mannose. Glucose can be considered as a marker for wheat adulteration and fructose for soybean, respectively. These results correspond to polysaccharides of pure raw grains, confirming this approach as a feasible analytical tool for detection of adulterants in ground roasted coffee.Food Research International 07/2014; · 3.05 Impact Factor
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ABSTRACT: Rice beer samples of nine different varieties from four states of northeast India were studied for the content of organic acids, carbohydrates and amino acids by high-performance liquid chromatography. The aromatic compounds were detected by gas chromatography–mass spectrometry method. The analysis evinced a wide variation in content of the major organic acids. Lactic acid was found in high concentration in all of the samples, while the other organic acids were present in variable amounts. Among the carbohydrates, glucose was predominant and some other monosaccharides were also detected. Most of the essential amino acids were found to be present and among them aspartic acid was the most abundant. All of the samples contained volatile or semi-volatile aromatic compounds, with phenylethyl alcohol being the most abundant compound. The overall study revealed that this form of drink has important nutritional values for dietary requirements. Copyright © 2014 The Institute of Brewing & DistillingJournal of the Institute of Brewing. 04/2014; 120(3).
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ABSTRACT: Coffee is one of the most consumed beverages in the world. Due to its commercial importance, the detection of impurities and foreign matters has been a constant concern in fraud verification, especially because it is difficult to percept adulterations with the naked eye in samples of roasted and ground coffee. In Brazil, the most common additions are roasted materials, such as husks, sticks, corn, wheat middling, soybean, and more recently - acai palm seeds. The performance and correlation of two chromatographic methods, HPLC-HPAEC-PAD and post-column derivatization HPLC-UV-Vis, were compared for carbohydrate analysis in coffee samples. To verify the correlation between the two methods, the principal component analysis for the same mix of triticale and acai seeds in different proportions with coffee was employed. The performance for detecting adulterations in roasted and ground coffee of the two methods was compared.Food Chemistry 03/2014; 146:353-62. · 3.26 Impact Factor