Study by LC/ESI/MS and ESI/HR/MS of SO2 interactions in flavanols–aldehydes nucleophilic reactions

The study concerns the interactions between (+)-catechin and a representative oak wood aldehyde (5-(hydroxymethyl)furfuraldehyde for furanic aldehydes and vanillin for phenolic aldehydes) in a wine-like model solution in presence or not of SO₂. The formed condensation products were characterised by LC/MS, LC/ESI/MSⁿ, and ESI/HR/MS and we studied the effect of SO₂ on these condensation reactions.     

Simultaneous determination of aging markers in sugar cane spirits

In this work a method for simultaneous determination of 10 representative compounds in sugar cane spirits is reported. The low molecular weight phenolic compounds: gallic acid; vanillic acid; syringic acid; vanilin; syringaldehyde; coniferaldehyde; sinapaldehyde and coumarin; and the furanic aldehydes: 5-hydroxymethyl-furfural and furfural were simultaneously quantified by high performance liquid chromatography with UV detection. These compounds, together with acids, aldehydes and tannins are responsible for the organoleptic properties of aged beverages and can assest product quality, as well as be used as aging indicators. Determination of this group of compounds is important, as they are characteristic of types and styles of aged beverages.     

Effect of copper on oxidation of (+)-catechin in a model solution system

Summary Autoxidation of ( +)‐catechin in a model solution system, containing cupric ions, was monitored by high‐performance liquid chromatography with diode array detection. The rate of (+)‐catechin oxidation and the extent of browning increased with the copper concentration, showing an effect of copper on browning of flavanols. The progression of the reaction showed that the appearance of new compounds, which were initially absent in the mixture, was concomitant with (+)‐catechin decrease. Numerous reaction products, including both colourless compounds and pigments absorbing at 440, 460 and 550 nm, were detected. Among the colourless derivatives, four dimeric compounds, consisting of two catechin units linked by a carboxymethine bridge, were detected. Their formation involved the condensation of flavanols, mediated by glyoxylic acid, following a mechanism similar to that previously observed with iron. The yellowish compounds that were detected were identified as xanthylium salts and their corresponding esters, showing absorption maxima at 440 and 460 nm, respectively. Comparison of the results obtained with those reported with iron showed that copper ions play similar roles in enhancing the oxidation rate of (+)‐catechin and flavanols.     

An Alternative Method for the Determination of Some of the Antioxidant Phenolics in Varietal Turkish Red Wines

The concentration of eight biologically important phenolic compounds (β‐coumaric acid, gallic acid, ferulic acid, caffeic acid, trans‐resveratrol, quercetin, (+)‐ catechin and (?)‐ epicatechin) of red wines produced on a pilot plant scale were determined using gas chromatography with mass spectrometric detection in the selective ion monitoring mode (GC/MS‐SIM). The procedure involved an easy fractionation and liquid‐liquid extraction method. For derivatization, BSA [N,O‐bis‐trimethylsilyl aceta‐mide] / TMCS was used. The results showed that the p‐coumaric acid, gallic acid, ferulic acid, caffeic acid, trans‐resveratrol, quercetin, (+)‐ catechin and (?)‐epicatechin levels in the wine samples ranged between 2.05 and 4.21 mg/L; 21.78 and 60.83 mg/L; 0.33 and 0.82 mg/L; 1.50 and 4.06 mg/L; 0.96 and 3.93 mg/L; 2.66 and 3.14 mg/L; 8.72 and 11.30 mg/L; 5.50 and 9.58 mg/L, respectively. Although the quercetin and trans‐resveratrol levels of Turkish red wines were similar to previously reported values, (+)‐ catechin and (?)‐ epicatechin levels were lower than the values of red wines originating from other countries.     

Phenolic and furanic compounds of Portuguese chestnut and French, American and Portuguese oak wood chips

Botanical species used on aging process must be wisely and judiciously chosen, and for this selection, a basic knowledge of the chemical composition of woods is warranted. Aiming to contribute to extend the knowledge of the chemical composition of several wood species useful for enological purposes, we have focused our studies on Portuguese chestnut and French, American and Portuguese oak chips. The profile of low molecular weight phenolic composition of these chips was achieved, using an optimized extraction method based on pressurized liquid extraction, followed by the quantification of phenolic acids, phenolic aldehydes and furanic derivatives by high-performance liquid chromatography (HPLC-DAD). The identification of those compounds was also confirmed by LC-DAD/ESI-MS. This study allowed the determination of the low molecular phenolic composition of Portuguese chestnut and French, American and Portuguese oak wood. According to our results, the influence of the botanical species seems to be more relevant than the geographic origin of the wood species.     

Effect of reaction pH and CuSO4 addition on the formation of catechinone due to oxidation of (+)‐catechin

A novel hair dyeing technique being milder and safer for a human body is desired. The oxidation product of (+)‐catechin, catechinone, was invented as a safer dyestuff for hair colouring under such the situation. The preparation of catechinone by a chemical oxidation is a practical way and the objective of the study is clarify the effect of the solution pH and in the presence or absence of Cu²⁺ on the formation rate and yield of catechinone in order to improve the efficiency of the dye formation. The catechinone formation was monitored by ultraviolet‐visible spectroscopy. Catechinone was prepared chemically from (+)‐catechin in aqueous solution with O₂ gas introduced over a pH range of 7.1–11.7. The rate and amount of the dye formation increase with increasing pH. Dissociation of the hydroxyl group of the catechol part of (+)‐catechin is significant for the oxidation of (+)‐catechin and promotes the dye production. This is because the deprotonated (+)‐catechin has a higher reactivity with O₂. The production of catechinone is accelerated by the addition of CuSO₄ and the production rate reaches the maximum at pH = 8.8. (+)‐Catechin ‐ Cu²⁺ complexes are formed and the formation promotes the oxidation of the catechol part of (+)‐catechin at pH ≤ 8.8. On the other hand, the complex becomes too stable to proceed for the oxidation reaction at pH > 8.8.     

Structural diversity of nucleophilic adducts from flavanols and oak wood aldehydes

The reactions between (+)-catechin and a representative oak wood aldehyde (furfuraldehyde, 5-(hydroxymethyl)furfuraldehyde, 5-methylfurfuraldehyde, vanillin, or syringaldehyde) in a wine-like model solution were studied and the formed condensation products were characterized by LC/MS and LC/MS/MS.     

高效液相色谱法测定菠萝中多酚类化合物

利用高效液相色谱法(HPLC)分析了多酚类物质在菠萝果皮、果肉、果心中的含量及分布情况。色谱条件：色谱柱为 Diamonsil C_(18)柱(250 mm×4．6 mm,5μm),流动相为乙腈和0．3%醋酸溶液,柱温为25℃,流速为 1．0mL/min,线性梯度洗脱,检测波长为280nm。在此色谱条件下,各组分均得到良好分离。经测定,菠萝果皮中含有4种酚类物质,为没食子酸、儿茶素、表儿茶素、阿魏酸,含量较高；果肉及果心中酚类物质为表儿茶素和阿魏酸,含量较低。     

Phenolic profile and free radical‐scavenging activity of Cabernet Sauvignon wines of different geographical origins from the Balkan region

BACKGROUND: The phenolic profile, determined by the relative proportions of different phenolic compounds, is characteristic for each grape variety and its corresponding wine. The aim of this study was to determine the phenolic and hydroxycinnamate acid, flavan‐3‐ol and flavonol contents and free radical‐scavenging activity of single‐cultivar (Cabernet Sauvignon) wines from selected Balkan vineyard regions by spectrophotometric methods and high‐performance liquid chromatography with photodiode array and fluorescence detection. RESULTS: The contents of phenolic compounds varied depending on the agroclimatic factors and oenological practices of the vineyard region. The antioxidant activity of wine samples was estimated by their ability to scavenge the stable 2,2′‐diphenyl‐1‐picrylhydrazyl free radical (DPPH). All wines showed high DPPH‐scavenging activity (70.03–83.53%, mean 73.76%). Significant correlations between catechin (R² = 0.8504) and quercetin (R² = 0.8488) concentrations and DPPH‐scavenging ability of the wines were found. CONCLUSION: The concentrations of the main components catechin and quercetin can be used as biochemical markers for the authentication of red grape cultivars and their corresponding single‐cultivar wines. Copyright © 2010 Society of Chemical Industry     

Effect of oak wood on the quality of beer

Maturation in wood is an important practice that is widely used in the production of high‐quality beverages. The effect of French oak cubes on young lager beer was studied. Oak cubes (with light, medium or heavy toasting) were added to the beer, which was stored at 0°C for 3 months. Beer samples were analysed monthly, and an acceptance test was performed at the end of 3 months. The content of volatile compounds (aldehydes, esters and higher alcohols) was determined by gas chromatography using a flame ionization detector, and the content of low molecular weight phenolic compounds was determined by high‐performance liquid chromatography. The contents of aldehydes, esters, higher alcohols and wood‐derived compounds increased during the 3‐month maturation period. Lager beer stored with heavily toasted oak cubes had the highest concentration of low‐molecular‐weight phenolic compounds, followed by the beer matured in an oak barrel. These results suggest that beer maturation in wood barrels or with oak cubes changed the composition of their oak‐related aromatic compounds, indicating that interactions between the beer and the wood occurred. Copyright © 2015 The Institute of Brewing & Distilling     

Determination of aldehydes in tequila by high-performance liquid chromatography with 2,4-dinitrophenylhydrazine derivatization

In this work, the determination of aldehydes in different tequila brands was carried out by high-performance liquid chromatography after derivatization with 2,4-dinitrophenylhydrazine. For the comparative purposes, two commercial brandies were also analyzed. The derivatization agent (50 μl of 3.5 mmol l⁻¹ DNPH in HCl, 2 mol l⁻¹) was added directly to the sample (500 μl) and dinitrophenylhydrazones formed were extracted with hexane. After evaporation of the solvent in nitrogen stream, the residues were dissolved in 100 μl of acetonitrile. The calibration standards were prepared from respective dinitrophenylhydrazones, following the same procedure as for beverage samples. Reversed phase chromatographic separation was achieved on Luna C18 column (250 mm×4.6 mm, 5 μm), using gradient elution (acetonitrile:water, from 68 to 80% of acetonitrile in 20 min) and a total flow rate 1 ml min⁻¹. Spectrophotometric detection for furanic aldehydes was at 390 nm (for other aldehydes at 365 nm). The assignation of chromatographic peaks was accomplished by comparison of their relative retention times and UV/Vis spectra with those of external standards. The method of standard addition was also used. The aldehydes identified were 5-hydroxymethylfurfuraldehyde (t _ret=4.1 min), formaldehyde (t _ret=5.1 min), syringaldehyde (t _ret=5.6 min), acetaldehyde (t _ret=6.2 min), 2-furaldehyde (t _ret=7.2 min) and 5-methylfurfuraldehyde (t _ret=8.9 min). At least four chromatographic peaks with retention times higher than 12 min remained unidentified. The quantification results showed drastically higher concentrations of 2-furaldehyde and 5-methylfuraldehyde in tequilas as referred to brandies. Furthermore, 100% tequilas contained higher levels of these two compounds (for four brands analyzed, mean values 18.6 and 5.97 μg ml⁻¹, respectively) as compared to the mixed brands (five brands analyzed, mean values 6.46 and 3.30 μg ml⁻¹). The results obtained confirm that the profile of furanic aldehydes depends on the type of fructans contained in the raw material and also on heating treatment applied or not prior to fermentation. In contrast to other polysaccharides, inulin hydrolyzes at elevated temperature and the contribution of Maillard browning reactions increases the production of furanic compounds. Our results indicate that the levels of 2-furaldehyde and 5-methylfuraldehyde could be used for discrimination between 100% and mixed tequila brands.     

Mass spectrometry fragmentation pattern of coloured flavanol‐anthocyanin and anthocyanin‐flavanol derivatives in aged red wines of Rioja

Background and Aims: During wine ageing, a great variety of reactions take place, resulting in an immense variety of products whose structure sometimes remains unknown. The aim of this work is the study of different fragmentation patterns of flavanol‐anthocyanin derivatives formed along the wine ageing; these patterns are useful for elucidating the different structures of these compounds and other new related ones. Methods and Results: Several wines from the Protected Denomination of Origin Rioja have been studied by an analytical method that combines column chromatography and high‐performance liquid chromatography with diode array and mass and tandem mass spectrometric detections. Thirty‐five coloured flavanol‐anthocyanin compounds formed by direct reaction or by acetaldehyde‐mediated condensation have been identified. For direct reaction derivatives, two different fragmentation patterns (one of them not previously reported) have been observed depending on the position of flavanol in the coloured derivative. Several compounds have been identified in aged wines for the first time to the authors' knowledge, like (+)‐gallocatechin‐cyanidin‐3‐glucoside and (+)‐catechin‐cyanidin‐3‐glucoside Conclusions: The developed analytical procedure has allowed the identification of some compounds for the first time, and two different fragmentation patterns have been observed depending on the position of flavanol in the pigment. Significance of the Study: The establishment of different fragmentation patterns allows the structural elucidation of unknown compounds.     

Determination of purine alkaloids and catechins in different parts of Camellia assamica var. kucha by HPLC‐DAD/ESI‐MS/MS

BACKGROUND: Kucha (Camellia assamica var. kucha) is a novel wild tea resource grown in China and a tea plant containing a sizable amount of theacrine (1,3,7,9‐tetramethyluric acid). High‐performance liquid chromatography (HPLC) analysis of purine alkaloids and catechins in young leaves of Kucha has been reported previously. However, the compositions of purine alkaloids and catechins in other parts of the plant remain unknown, and more information about the chemical constituents of Kucha is also necessary for further research and development of this new tea resource. RESULTS: Using HPLC with diode array detection coupled with electrospray ionisation tandem mass spectrometry (HPLC‐DAD/ESI‐MS/MS), three purine alkaloids, seven catechins and four non‐catechin phenolic compounds were identified or tentatively identified in Kucha. Purine alkaloids and catechins in leaves at different developmental stages, flowers, stems, pericarps and seeds of the plant were also quantified for the first time by the HPLC method, which was fully validated. Recoveries of the quantified compounds ranged from 96.67 to 104.33%. CONCLUSION: The results showed that the total contents of purine alkaloids and catechins were highest in young leaves of Kucha. Theacrine was detected in all parts of the plant and found to be most abundant in pericarps. Copyright © 2009 Society of Chemical Industry     

Effect of ellagitannins,ellagic acid and volatile compounds from oak wood on the (+)‐catechin,procyanidin B1 and malvidin‐3‐glucoside content of model wines

Background and Aims: During ageing in oak barrels, wine undergoes changes because of the release of polyphenols and other molecules from wood. The aim of this study was to evaluate the influence of some oak wood‐derived volatile compounds, ellagic acid and oak wood extracts on the levels of (+)‐catechin, procyanidin B1 and malvidin‐3‐glucoside. Methods and Results: Phenolics and the oak wood derived volatile compounds studied were quantified by HPLC and by GC, respectively. Additionally, the new compounds formed in the solutions were characterised by their spectral properties. Ellagic acid and/or oak wood extracts slowed the decline in the levels of (+)‐catechin and procyanidin B1. In contrast, the decrease in malvidin‐3‐glucoside was more pronounced in the presence of ellagic acid and oak wood chip extracts. Furfural slowed (+)‐catechin degradation, while breakdown of malvidin‐3‐glucoside was slightly more pronounced in the presence of guaiacol, furfural, vanillin and eugenol. (+)‐Catechin, procyanidin B1 and malvidin‐3‐glucoside did not significantly affect the rate of the degradation of ellagitannins during the storage time studied. Finally, new HPLC peaks were detected in the solutions containing (+)‐catechin and ellagic acid, as well as with malvidin‐3‐glucoside with ellagic acid and oak wood extract. Conclusions: Malvidin 3‐glucoside and (+)‐catechin and procyanidin B1 presented distinct behaviours during time in the presence of volatile and non‐volatile compounds from oak wood. Significance of the Study: This work points out the importance of oak wood components in the degradation of anthocyanins and tannins, as well as the reactions that occur during the ageing of red wine.     

Phenolic composition of European cranberrybush (Viburnum opulus L.) berries and astringency removal of its commercial juice

Phenolic composition of the European cranberrybush (ECB) (Viburnum opulus L.) juice was determined using high‐performance liquid chromatography. The juice contained 2037 mg kg^?1 chlorogenic acid, which was 54% of total phenolics, and several other phenolics such as (+)‐catechin, (?)‐epicatechin, cyanidin‐3‐glucoside, cyanidin‐3‐rutinoside and six different glucosides of quercetin. Because of its strong astringent taste, the juices were treated with various doses of two different types of activated carbons (Granucol Bi and Granucol Ge) in order to remove phenolic compounds. Results revealed that both types of activated carbons were equally effective on astringency removal (P < 0.01). A 20–30% reduction in total phenolics was achieved by application of 2.0–3.0 g L^?1 activated carbon which also removed unpleasant taste and odour.     

Effects of catechin on the phenolic content and antioxidant properties of low‐fat cheese

The effect of (+)‐catechin on total phenolic content (TPC) and antioxidant properties in low‐fat hard cheese were examined over a 90‐day ripening period at 8 °C. Antioxidant activity (AA) in cheese was measured by ferric reducing antioxidant power, oxygen radical absorbance capacity (ORAC) and 2,2‐diphenyl‐1‐picrylhydrazyl assays and compared with TPC. Catechin retention coefficients in cheese curds were in the range of 0.63–0.75 and decreased the pH of cheese without affecting protein, fat or moisture content. Both TPC and AA increased during the 90‐day ripening period. Oxygen radical absorbance capacity was the most suitable technique for evaluating AA in cheese due to the high correlation with TPC and suitability in both lipophilic and hydrophilic systems.     

Optimizing the orosensory properties of model functional beverages: the influence of novel sweeteners, odorants, bitter blockers, and their mixtures on (+)-catechin

This paper is dedicated to the memory of colleague and friend, Dr. Samson Agboola, who recently passed away. Abstract: The use of flavor‐modifying strategies are important to improving the sensory profile of some excessively bitter and astringent functional ingredients, such as (+)‐catechin (CAT). Two bitter blockers (ß‐cyclodextrin [CYCLO], homoeriodictyol sodium salt [HED]), two sweeteners (sucrose [SUC], rebaudioside A [REB]), and two odorants (vanillin [VAN], black tea aroma [TEA]) were assessed for their efficacy at modifying the bitterness and astringency of CAT in model aqueous solutions. The intensity of oral sensations elicited by CAT was determined in duplicate in binary, ternary, and quaternary mixtures of these stimuli by a trained panel (n= 15) using a 15 cm visual analogue scale. Overall, bitterness and astringency were most effectively reduced by ternary solutions containing CYCLO + REB or CYCLO + SUC (68%, 60%, and 45%, 43% for bitterness and astringency, respectively). Odorants were not effective at modifying the bitterness or astringency of CAT. We conclude that the use of select bitter blockers and sweeteners may be of value in optimizing the flavor and acceptance of functional food and beverages fortified with phenolic compounds. Practical Application: (+)‐Catechin is a bitter‐tasting plant‐derived health‐promoting phenolic compound of interest to functional food and beverage manufacturers. We investigated the efficacy of bitter blockers, plant‐based sweeteners, and odorants in decreasing the bitterness and astringency elicited by (+)‐catechin. Some of these additives, both alone and in combination, reduced bitterness and astringency, and may therefore assist in optimizing the flavor and consumer acceptance of some phenolic‐based functional foods and beverages.     

Correlation between Antimicrobial,Antioxidant Activity,and Polyphenols of Alkalized/Nonalkalized Cocoa Powders

Many factors can influence antioxidative and antimicrobial characteristics of plant materials. The quality of cocoa as functional food ingredient is influenced through its processing. The main aim of this study was to test if there is difference in polyphenol content, antioxidant capacity, and antimicrobial activity between nonalkalized and alkalized cocoa powders. To estimate polyphenol and flavonoid content in cocoa samples the spectrophotometric microassays were used. Flavan‐3ols were determined with reversed‐phase high‐performance liquid chromatography (RP‐HPLC). Antimicrobial activity against 3 Gram positive bacteria, 4 Gram negative bacteria and 1 strain of yeast was determined using broth microdilution method. Total polyphenol content was 1.8 times lower in alkalized cocoa samples than in natural ones. Epicatechin/catechin ratio was changed due to the process of alkalization in favor of catechin (2.21 in natural and 1.45 in alkalized cocoa powders). Combined results of 3 antioxidative tests (DPPH, FRAP, ABTS) were used for calculation of RACI (Relative Antioxidant Capacity Index) and GAS (Global Antioxidant Score) values that were consistently higher in natural than in alkalized cocoa extracts. Obtained results have shown significant correlations between these values and phenolic content (0.929 ≤ r ≤ 0.957, P < 0.01). Antimicrobial activity varied from 5.0 to 25.0 mg/ml (MICs), while Candida albicans was the most sensitive tested microorganism. Cocoa powders subjected to alkalization had significantly reduced content of total and specific phenolic compounds and reduced antioxidant capacity (P < 0.05), but their antimicrobial activity was equal for Gram‐positive bacteria or even significantly enhanced for Gram‐negative bacteria.     

(+)‐Catechin and (−)‐epicatechin levels of concentrated and ready‐to‐drink grape juices through storage

Commercial concentrated Concord (CCJ) and Isabel (CIJ) grapes juices were stored at 4–5 °C while pasteurised ready‐to‐drink juices of the same grape cultivars (PCJ and PIJ) were kept at 20–25 °C under indirect light for 10 months, simulating industrial storage conditions. (+)‐catechin preservation during storage ranged between 63% (PCJ) and 52% (PIJ); (?)‐epicatechin retention was of 32% (CCJ) and 15% (CIJ). Total phenols retention ranged from 93% (CCJ) to 84% (PCJ) and radical scavenging activity (RSA) from 87% (PIJ) to 85% (CCJ and PCJ). Concentrated juices showed higher monomeric flavan‐3‐ols amounts and CCJ depicted superior phenolic contents. PIJ yielded the highest RSA during storage per phenolic unit. Process and storage impacted flavan‐3‐ols and not total phenolics and RSA during 10‐month ageing.     

高效液相色谱-串联质谱测定黄冠梨果皮中主要酚类物质

为研究黄冠梨果皮中的主要酚类物质,采用了高效液相色谱—串联质谱方法定性、定量检测黄冠梨果皮中主要酚类物质,并评价该方法定量分析的准确性、线性和检出限。以甲醇—1%乙酸溶液为流动相做梯度洗脱,柱温30℃,检测波长280 nm,流速为0.6 mL/min;质谱检测在负离子模式下,利用全扫描模式、多反应检测模式和中性丢失模式进行。在此方法下,样品中的酚类物质在50 min内得到分离并由色谱的保留时间和质谱信息确定。结果表明:黄冠梨果皮中共检测出15种酚类物质,主要以绿原酸含量最多,含量为65.765 2 mg/100gDW,其次是熊果苷、儿茶素、香豆酸、咖啡酸、槲皮素等。