Magdalena Jeszka-Skowron

Analytical methods applied for the characterization and the determination of bioactive compounds in coffee

Coffee, the one of the most popular beverages in the world, contains many bioactive compounds especially caffeine—the natural stimulant and chlorogenic acids with antioxidative properties. Other chemicals such as diterpenes may influence human serum lipids and protect from the risk of some types of cancer. All these compounds are widely determined in Coffea arabica and robusta green and roasted coffee beans, coffee brews and instant coffees to increase food quality standards. The most important analytical methods are reviewed, including these using high-performance liquid chromatography, ultraviolet spectrophotometry and voltammetry techniques, that have been applied to quantify the major bioactive compounds of coffee samples: phenols—inter alia chlorogenic acids and derivatives; methylxanthines—caffeine; trigonelline; nicotinic acid; diterpenes; and short-chain carboxylic acids. Usage of hyphenated techniques such as liquid chromatography–mass spectrometry and gas chromatography–mass spectrometry for identification and determination of coffee constituents is also presented.

Potential health benefits and quality of dried fruits: Goji fruits, cranberries and raisins

Dried fruits are important snacks and additives to other foods due to their taste and nutritional advantages. Therefore there is an important goal to control the quality of the food on the market for consumers safety. Antioxidant activity of goji fruits (Lycium barbarum), cranberries (Vaccinium macrocarpon and oxycoccus) and raisins (Vitis vinifera) were studied using the DPPH (2,2-diphenyl-1-picrylhydrazyl) and Folin-Ciocalteu assays. Cu, Mn and Ge influencing antioxidant activity were determined together with selected toxic metals (Cd, Ni and Pb). Contamination with fungi was studied by quantification of their marker - ergosterol and important mycotoxins (aflatoxins B1, B2, G1 and G2, and ochratoxin A) were also determined. Antioxidant activity of all tested dried fruits was confirmed with goji fruits being the most profitable for consumers. Contamination of the tested fruits with toxic metals and mycotoxins was low.

Application of dendrimer modified halloysite nanotubes as a new sorbent for ultrasound-assisted dispersive micro-solid phase extraction and sequential determination of cadmium and lead in water samples

The combination of ultrasound-assisted dispersive micro-solid phase extraction (USA DMSPE) and high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) was developed for the sequential determination of cadmium and lead in water samples. During the preconcentration step, dendrimer modified halloysite nanotubes (HNTs-G3) were used as a solid sorbent. Fourier transform infrared (FTIR) spectroscopy was used to characterize HNTs during the modification steps. HNTs-G3 were dispersed in water samples containing trace elements to be determined. After the sorption, the aqueous samples were separated by centrifugation. Then, the metal loaded HNTs-G3 were suspended using a small volume of deionized water and introduced into an atomizer. The main extraction and detection parameters were investigated. The concentration limits of detection were 0.5 and 10 ng L−1 for Cd and Pb, respectively. The preconcentration factors achieved for Cd and Pb were 46 and 41, respectively. The relative standard deviations (RSDs) were 4% and 5% for Cd and Pb, respectively. The accuracy of this method was validated by analyses of NIST SRM 1643e (Trace Elements in Water), TMRAIN-04 (Rainwater) and ERM – CA011b (Hard Drinking Water). The measured element contents in these reference materials were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level. The proposed method has been successfully applied to the determination of cadmium and lead in six different water samples (seawater, lake water, river water, stream water, mine water and tap water).

Determination of Parabens in Polish River and Lake Water as a Function of Season

ABSTRACT A method for the determination of methylparaben, ethylparaben, propylparaben, butylparaben, and benzylparaben is reported. A polymeric cartridge containing ultra-pure polystyrene cross-linked with 50% divinylbenzene and 50% poly(methyl methacrylate) was employed for the isolation of parabens from water samples. The extracted samples were analyzed by high-performance liquid chromatography coupled with tandem mass spectrometry. The limits of detection for the method were from 0.3 to 2.9 ng L−1 that allowed the determination of parabens in river and lake water samples with suitable precision and accuracy. There was high variability in the results depending on time of sample collection. The highest concentrations were obtained for samples collected in July – up to 466 ng L−1 of methylparaben and 144 ng L−1 of propylparaben.

Determination of parabens in cosmetic products using high performance liquid chromatography with fluorescence detection

Parabens are preservatives with a broad spectrum of antimicrobial activity widely used in cosmetics, foods and pharmaceuticals. Reports suggesting estrogenic activity and lack of appropriate data on safety of some parabens led to introduction of law legislation restricting their use in cosmetics. As a result, only methylparaben, ethylparaben, propylparaben and butylparaben can be currently used in the European Union with concentrations restricted to below 1%. Therefore, a simple analytical method using HPLC with fluorescence detection was developed for the determination of these parabens in cosmetic products including tonics, micellar waters and eau de toilettes. The high sensitivity and selectivity of fluorescence detection (with excitation and emission wavelengths set to 254 nm and 310 nm, respectively) as well as appropriate chromatographic separation (with a methanol–water gradient on an octadecylsilica column) enabled analysis with very simple sample preparation including only a dilution step. The obtained limits of quantitation in the range from 24 to 46 μg mL−1 enabled the determination of parabens in accordance with the regulations issued by the European Parliament and the Council while only very simple and inexpensive laboratory equipment was used. Over 20 cosmetic samples were tested and the determined parabens were not exceeding the established limits. The samples were also subjected to HPLC analysis with mass spectrometric detection which confirmed the obtained results.

Positive and negative aspects of green coffee consumption - antioxidant activity versus mycotoxins: Positive and negative aspects of green coffee consumption

BACKGROUND The quality of coffee depends not only on the contents of healthy compounds but also on its contamination with microorganisms that can produce mycotoxins during development, harvesting, preparation, transport and storage. RESULTS The antioxidant activity of green coffee brews measured in this study by ABTS, DPPH and Folin-Ciocalteu assays showed that coffee extracts from Robusta beans possessed higher activity in all assays than extracts from Arabica beans. The occurrence of ochratoxin A and aflatoxins (B1, B2, G1 and G2) in green coffee beans was studied using liquid chromatography/mass spectrometry. Apart from mycotoxins, the content of ergosterol as a marker indicating fungal occurrence was also determined. Among aflatoxins, aflatoxin B1 was the dominant mycotoxin in coffee bean samples, with the highest level at 17.45 ng g-1 . Ochratoxin A was detected in four samples at levels ranging from 1.27 to 4.34 ng g-1 , and fungi potentially producing this toxin, namely Aspergillus oryzae, Alternaria sp., Aspergillus foetidus, Aspergillus tamarii and Penicillium citrinum, were isolated. CONCLUSION Steaming and decaffeination of coffee beans increased antioxidant activities of brews in comparison with those prepared from unprocessed beans. Although toxins can be quantified in green coffee beans and novel fungi were isolated, their concentrations are acceptable according to legal limits.