Eating five servings of fruits and vegetables per day! This is what is highly recommended and heavily advertised nowadays to the general public to stay fit and healthy! Drinking green tea on a regular basis, eating chocolate from time to time, as well as savoring a couple of glasses of red wine per day have been claimed to increase life expectancy even further! Why? The answer is in fact still under scientific scrutiny, but a particular class of compounds naturally occurring in fruits and vegetables is considered to be crucial for the expression of such human health benefits: the polyphenols! What are these plant products really? What are their physicochemical properties? How do they express their biological activity? Are they really valuable for disease prevention? Can they be used to develop new pharmaceutical drugs? What recent progress has been made toward their preparation by organic synthesis? This Review gives answers from a chemical perspective, summarizes the state of the art, and highlights the most significant advances in the field of polyphenol research.

Plant Polyphenols: Chemical Properties, Biological Activities, and Synthesis

Extraction and analysis of phenolics in food

Phenolics in cereals, fruits and vegetables: Occurrence, extraction and analysis

The impetus for developing analytical methods for phenolic compounds in natural products has proved to be multifaceted. Hundreds of publications on the analysis of this category of compounds have appeared over the past two decades. Traditional and more advanced techniques have come to prominence for sample preparation, separation, detection, and identification. This review provides an updated and extensive overview of methods and their applications in natural product matrices and samples of biological origin. In addition, it critically appraises recent developments and trends, and provides selected representative bibliographic examples.

Extraction, separation, and detection methods for phenolic acids and flavonoids

http://chglib.icp.ac.ru/subjex/2013/pdf02/ChemPhysicsLetters-2010-487(1-3)1.pdf

Quantum cascade lasers in chemical physics

Mid-infrared spectroscopy and UV−vis spectroscopy combined with multivariate data analysis have been applied for the discrimination of Austrian red wines, including the cultivars Cabernet Sauvignon, Merlot, Pinot Noir, Blaufrankisch (Lemberger), St. Laurent, and Zweigelt. Both authentic wines and their phenolic extracts were investigated by attenuated total reflectance (ATR)−mid-infrared spectroscopy. Phenolic extracts were also investigated by UV−vis spectroscopy. The wine extracts were obtained by solid-phase extraction with C-18 columns and elution by methanol containing 0.01% hydrochloric acid. Hierarchical cluster analysis was performed with mid-infrared spectra of both wines and extracts, as well as with UV−vis spectra of the phenolic extracts. Data processing involved vector normalization and derivation of the spectra. Due to varying concentrations of main components including sugar and organic acids, satisfactory classification of untreated wines was not achieved. However, when using mid-infrared ...

Rapid Method for the Discrimination of Red Wine Cultivars Based on Mid-Infrared Spectroscopy of Phenolic Wine Extracts

The interaction of polyphenols (tannins) with proline-rich proteins (gelatin) has been studied using an automated flow injection system with Fourier transform infrared spectroscopic detection to gain insight into chemical aspects related to astringency. In the perception of astringency, a major taste property in red wines and other beverages such as beer, tea, or fruit juices, an interaction between proline-rich salivary proteins and tannins present in the sample takes place. To study this interaction, agarose beads carrying gelatin (a proline-rich protein) were placed in the IR flow cell in such a way that the beads were probed by the IR beam. Using an automated flow system, we injected samples in a carrier stream and flushed over the proteins in a highly reproducible manner. Simultaneously, any retardation due to tannin-protein interactions taking place inside the flow cell was monitored by infrared spectroscopy. Tannins of different sources (grapes, wooden barrels, formulations used in wine making) were investigated, and their flow-through behavior was characterized. Significant differences in their affinity toward gelatin could be observed. Furthermore, because of small but characteristic differences in the IR spectrum, it is possible to distinguish condensed from hydrolyzable tannins. Nonastringent substances such as alcohols, sugars, and acids did not show retention on gelatin. The selectivity of the flow-through sensor was also demonstrated on the example of red and white wine. In contrast to white wine, where no interaction could be observed, in red wine a major interaction of the red wine tannins was found.

Toward the Optical Tongue: Flow-Through Sensing of Tannin−Protein Interactions Based on FTIR Spectroscopy

A nondestructive analytical method for peroxide-based explosives determination in solid samples is described. Reversed-phase high-performance liquid chromatography in combination with on-line Fourier transform infrared (FT-IR) detection is used for the analysis of triacetonetriperoxide (TATP) and hexamethylenetriperoxide diamine (HMTD). In contrast to other liquid chromatographic methods with optical detection, no derivatization or decomposition of the peroxides is required. The peroxides are identified and quantified via their characteristic absorption spectra in the mid-infrared range of the electromagnetic spectrum. The detection limit of 0.5 mmol L-1 for HMTD and 1 mmol L-1 for TATP allows the identification of the explosives in complex matrixes.

Determination of peroxide-based explosives using liquid chromatography with on-line infrared detection.

A horizontal diamond attenuated total reflection (ATR) element has been incorporated in a flow-through cell with low dead volume and used for on-line mid-IR detection in high-performance liquid chromatography. The chemical inertness of the ATR element permitted the use of a strongly acidic mobile phase in the isocratic separation. The hyphenation was used for the analysis of organic acids, sugars and alcohols in red wine. In the case of co-eluting analytes multivariate curve resolution-alternating least squares (MCR-ALS) was successfully employed for quantitative analysis.

High-performance liquid chromatography with diamond ATR–FTIR detection for the determination of carbohydrates, alcohols and organic acids in red wine

https://publik.tuwien.ac.at/files/pub-tch_4951.pdf

Andrea Edelmann

Papers

Rapid Method for the Discrimination of Red Wine Cultivars Based on Mid-Infrared Spectroscopy of Phenolic Wine Extracts

Toward the Optical Tongue: Flow-Through Sensing of Tannin−Protein Interactions Based on FTIR Spectroscopy

Determination of peroxide-based explosives using liquid chromatography with on-line infrared detection.

High-performance liquid chromatography with diamond ATR–FTIR detection for the determination of carbohydrates, alcohols and organic acids in red wine

Towards functional group-specific detection in high-performance liquid chromatography using mid-infrared quantum cascade lasers.