In vitro antioxidant activity of red grape skins

Phenolic antioxidants seem to be partly responsible for the protective effects against cardiovascular diseases attributed to moderate wine consumption. Grape skins greatly contribute to the phenolic composition of red wine. In this paper, the in vitro antioxidant activity of red grape (Vitis vinifera) skins is determined. We show that the radical scavenging activity (C ₅₀ values) against 2,2-diphenyl-1-picrylhydrazyl (DPPH^·) of grape skin extracts is relatively high (3.2–11.1 mg dried skin/mg DPPH^·) in relation to other foodstuffs and, as expected, is influenced by grape variety, stage of grape ripening and vintage. The antioxidant potential of grape skins seems to be transferred into wine since grape varieties with skins exhibiting high antioxidant potential also resulted in wines with high antioxidant activity. Statistically significant correlations were found between antioxidant activity and phenolic content (total polyphenols, proanthocyanins, catechins and anthocyanins) for both grape skins and wines.     

Evolution of some phenolic components,carotenoids and chlorophylls during ripening of three Italian grape varieties

A typical Italian white grape cultivar (Erbaluce) and two red ones (Barbera and Nebbiolo), all grown in the same vineyard, were picked at various ripening stages, from differentiation of the berry to the harvest, and analysed by HPLC to determine carotenoids, chlorophylls and polyphenols, i.e. the major antioxidant components. With regard to carotenoids, mostly represented by β-carotene and lutein, similar initial concentrations were found in the three cultivars. After an initial increase, carotenoids content decreased in the three cultivars, followed in the red grapes by a new peak, mainly due to lutein. Chlorophylls decreased in all cultivars and they almost disappeared in the white grapes, while 14–20% of the initial concentration was found in the red ripe grapes. Total phenolics showed a progressive increase up to veraison, then a decrease occurred, which was counteracted in red grapes by the formation of anthocyanins. The evolution of catechins (as the sum of (+)catechin and (−)epicatechin) and flavonols (as the sum of rutin, quercetin and quercetin-3-glucoside) was similar in all grapes: initial concentration was low (about 1 mg/100 g dw), a peak corresponding to veraison was observed, then a rapid decline occurred to final concentrations between 10 and 20 mg/100 g dw. Climatic conditions and sun exposure seem to play an important role in the evolution of the components under investigation, since very similar profiles were observed in the three cultivars.     

Microwave-assisted extraction of phenolic antioxidant compounds from peanut skins

A microwave-assisted extraction system was used to extract phenolic antioxidants from peanut skins. The effects of microwave power (10%, 50%, 90% nominal), irradiation time (30, 90, 150 s) and sample mass (1.5, 2.5, 3.5 g) on total phenolic content (TPC), ORAC (oxygen radical absorbance capacity) level and resveratrol content of peanut skin extracts (PSE) were investigated. Peanut skins were extracted with 37.5 ml of 30% ethanol (EtOH) in water. A response surface method was used to estimate optimum extraction conditions, based on TPC, ORAC level and resveratrol content. The maximum predicted TPC, under the optimised conditions (90% microwave power, 30 s irradiation time and 1.5 g skins), was 143.6 mg gallic acid equivalent (GAE)/g skins. The highest ORAC value was 2789 μmol trolox equivalents (TE)/g skins, which occurred at 90% power, 150 s and 1.5 g of skins. Resveratrol was identified in PSE by LC–MS–MS analysis.     

Relationship between chemical structure and biosynthesis and accumulation of certain phenolic compounds in grape skins during ripening

Summary The presence of benzoic acids and flavonol aglycones in the skin of grapes grown in the Madrid region of Spain during ripening was studied by HPLC. Two grape varieties, one red (Cencibel) and one white (Airén), were considered from véraison to the industrial definition of berry maturity over 3 consecutive years. Syringic, vanillic,p-hydroxybenzoic, protocatechuic, and gallic acids and the flavonol aglycones myricetin, quercetin, kaempferol, and isorhamnetin were detected in both varieties, although syringic acid (detection limit 6 ng) was only recorded in the Cencibel grapes and isorhamnetin (detection limit 25 ng) was only recorded in Airén grape samples collected at around maturity. Programme 5R of the BMDP-87 statistical package was used to plot trends in the concentration of these components. The trends recorded were not linear but comprised patterns of alternating maxima and minima, and a relationship between the chemical structure of each compound and the distance between the maxima was found.

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Beziehung zwischen chemischer Struktur und Biosynthese zur Anhäufung phenolischer Verbindungen in der Haut der Weintraube während des Reifens

Zusammenfassung Es wurde die Anwesenheit von Benzoesäuren und Aglykonen von Flavonol in der Haut von Trauben des Madrid-Gebietes (Spanien), mittels HPLC, studiert. Beeren einer roten Sorte (Cencibel) und einer weißen Sorte (Airén) wurden von der Frühreife bis zur technologischen Reife in drei aufeinanderfolgenden Jahren untersucht. Vanillinsäure,p-Hydroxybenzoesäure, Protocatechusäure, Gallussäure, Myricetin, Quercetin und Kämpferol wurden in beiden Sorten nachgewiesen. Syringasäure (Nachweisgrenze: 6 ng) wurde nur in der Cencibel-Sorte nachgewiesen und Isorhamnetin wurde nur in der Airen-Sorte am Ende der Reifungszeit identifiziert. Die Bestimmungsgrenze liegt bei 25 ng. Die Studie über die Veränderungen der Konzentrationen der Substanzen wurde durch Anwendung des Programms 5R aus dem statistischen Softwarepaket BMDP-87 durchgeführt. Es wurde festgestellt, daß diese Konzentrationen, bei den verschiedenen Proben keine lineare Abhängigkeit von der Zeit aufweisen, sondern verschiedene Maxima und Minima. Eine Beziehung zwischen der chemischen Struktur jeder Verbindung und dem Abstand zwischen den Maximums wurde festgestellt.

     

Influence of grape variety on the extraction of anthocyanins during the fermentation on skins

The extraction of anthocyanins in the fermentation on skins is conditioned by several factors, such as the grape composition and the enological practices. In this work, the varietal effect on the anthocyanins extraction was studied, considering a series of fermentation on skins of Tannat, Cabernet-Sauvignon and Merlot. The different anthocyanic structures have a different diffusion in the must, at least during first stages of maceration. The decrease of the proportions of cyanidin and peonidin during the first days, with a consequent increase of the malvidin and petunidin proportions was verified. The coumarates proportions increased after the first day of maceration in all the musts. However, the definitive proportions of each anthocyanic form are reached rapidly and remain constant after the second or third day of maceration. The anthocyanic fingerprint of the young wines obtained in classical fermentation on skins is characteristic of each grape variety, although their evolution follows the general tendencies indicated.     

Effect of ripening stage of grapes on the low molecular weight phenolic compounds of red wines

Different red wines were elaborated to study the effect of the date of the grape harvest on the levels of individual low molecular weight phenolic compounds, which are chiefly responsible for the wine color. Two red grape varieties and two consecutive years were studied at three different harvesting stages of grapes, and the changes during the 18 months of wine aging (12 months in oak barrels and 6 months in the bottle) were also followed. The results showed that the wines made from grapes harvested 1 week later than the usual date generally had higher contents of some simple phenols, which can act as cofactors that can maintain the color intensity and violet tonalities in aged wines. Besides, these wines had lower levels of caftaric and coutaric acids, which are two of the main substrates for oxidation and browning processes.     

西拉葡萄果实成熟过程中果皮内非花色苷酚类物质的变化

利用高效液相色谱-质谱联用(HPLC-MS)技术研究西拉葡萄果实成熟过程中果皮内非花色苷酚类物质的变化.结果表明:在葡萄成熟过程中共检测到27种非花色苷酚类物质,其中黄酮醇类物质舍量最高,黄烷-3-醇类次之.各类非花色苷酚类的含量在转色开始逐渐上升,到转色后1～2周达到最大值,随后缓慢下降;采摘前2周,除了酚酸类物质含量趋于稳定、白藜芦醇含量下降之外,其它非花色苷酚类物质含量再次升高.     

Efficient isolation of major procyanidin A-type dimers from peanut skins and B-type dimers from grape seeds

In order to fully explore the biofunctional potential of proanthocyanidins (PA), isolated and well-characterised PA dimers are of great importance. Current methods to obtain pure A- and B-type dimers are laborious, because they comprise multiple chromatographic steps, often yielding only one or two specific dimers. In the current study, an efficient isolation procedure is described, to isolate a large variety of A-type dimers from peanut skins and B-type dimers from grape seeds. Yields increased 20–400 times for A-type dimers and about 10 times for B-type dimers compared to other methods with a lesser number of chromatographic steps. Dimers isolated from peanut skins were identified as; epicatechin-(2-O-7, 4-8)-catechin (A1), epicatechin-(2-O-7, 4-8)-epicatechin (A2), epicatechin-(2-O-7, 4-6)-catechin, epicatechin-(2-O-7, 4-8)-entcatechin, isolated from peanut skins for the first time, and epicatechin-(4-6)-catechin (B7). Dimers from grape seeds were identified as; epicatechin-(4-8)-catechin (B1), epicatechin-(4-8)-epicatechin (B2), catechin-(4-8)-catechin (B3) and catechin-(4-8)-epicatechin (B4).     

Rapid determination of the fatty acid profile in pork dry-cured sausages by NIR spectroscopy

The feasibility of using near infrared reflectance spectroscopy to evaluate the generation of relevant and accurate nutritional information through a rapid determination of the fatty acid profiles in Iberian pork dry-cured sausages was analysed. Individual fatty acids contents together with the saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acid (PUFA) groups were determined in 86 samples of Iberian dry-cured sausages. NIR calibrations were developed using modified partial least squared regressions. Selected models for the estimation of major constituents (C14:0, C16:0, C16:1, C18:0, C18:1 and C18:2) exhibited coefficients of determination for cross-validation which ranged between 0.41 and 0.84 with standard errors of cross-validation (SECV) between 0.07 and 1.51. Calibrations developed for SFA, MUFA and PUFA showed coefficients of determination of 0.86, 0.53 and 0.61, and SECV values of 0.98, 1.47 and 0.88, respectively. The results obtained suggest that in general, NIR spectroscopy could provide an exceptional opportunity for the quality control of dry-cured sausages, since it allows an estimation of the major constituents and/or a classification based on their fatty acid profiles rapidly whilst avoiding the generation of chemical residues. This information could be used to estimate shelf life of products and to include extra nutritional information associated to consumers’ health in their labelling.     

Use of commercial grape phenolic extracts to supplement solid foodstuff

Osmotic treatment (OT) has been applied to infuse phenolic compounds into a model food. Two commercial grape extracts were used as a source of phenolics, a grape seed extract (GSE) and a white grape marc extract (WGME). Three different concentrations of total phenolics were applied with and without presence of osmo-active solute (50 g/100 g and 0 g/100 g of sucrose) in the osmotic solution (OS). With a 50 g/100 g sucrose and a total phenolic content in OS ranging from 3 g/L to 15 g/L and operating time up to 8 h, the final total phenolic content in the osmo-treated model food was between 815 mg GAE/kg and 7176 mg GAE/kg. That is between the 0.5 and 1.5 times higher than that of the richest fruits. A soaking process with the same phenolic content but with no sucrose in OS led to a total phenolic content in the model food that was between 80% and 100% higher.Mass transfer of the major phenolics infused into the model food during OT and soaking process was characterized considering the diffusional approach and Peleg's model. Progress of total and individual phenolic content fitted well both models with the exception of the flavan-3-ol dimer concentration.     

Monitoring biochemical changes during grape berry development in Portuguese cultivars by NMR spectroscopy

¹H nuclear magnetic resonance (NMR) was applied for the metabolic profiling of grapes from three Portuguese cultivars including ‘Trincadeira’, ‘Aragonês’, and ‘Touriga Nacional’, at four developmental stages. Two kinds of extraction methods including deuterated NMR solvent extraction and solid phase extraction (SPE) were used for the metabolomic analysis and all the metabolites detected in ¹H NMR were elucidated by two-dimensional NMR techniques as well as the in-house NMR chemical shift database. Multivariate data analyses were also performed to identify overall metabolic differences. Trincadeira was found different from the other two cultivars, having low phenolic contents as compared to other cultivars. The initial stages showed comparatively high phenolics and organic acid contents like caftaric and malic acid while the later stages showed higher glucose and fructose levels. Veraison was found to be a metabolically critical stage of berry development. On the basis of these findings distribution of metabolites among different cultivars at different developmental stages is discussed.     

傅立叶近红外光谱法测定桃果中果胶含量

目的 基于傅里叶近红外光谱(Fourier transform near infrared)检测桃果中果胶含量的研究。方法 近红外光谱采集样品利用两个品种的桃,探究光谱预处理对建模的影响,建模采用偏最小二乘法(PLS)以及主成分回归(PCR)方法,模型的评价标准采用建模相关系数(R_C)、建模均方偏差(RMSE_C)、预测相关系数(R_P)、预测均方偏差(RMSE_P)。结果 两个品种的近红外光谱图和果胶含量无明显差异(P＞0.05),采用标准正态变量变换(SNV)和多元散射校正(MSC)对原始光谱的光程进行选择,所得建模结果影响基本一致,合适光谱数据格式以及平滑处理,能提高PLS和PCR模型的预测精度和稳定性。综合得出模型最佳是利用PLS方法建模并采用MSC/SNV结合一阶导数和 Savitzky-Golay (S-G)平滑对近红外光谱图进行预处理,评价参数分别为R_C=0.7795、R_P=0.7545、RMSE_C=0.0933、RMSE_P=0.0534和R_C=0.7800、R_P=0.7530、RMSE_C=0.0932、RMSE_P=0.0534。结论 该方法为利用近红外建模快速检测桃果中果胶含量提供重要依据。     

高速逆流色谱法分离红葡萄皮中的花色苷

建立高速逆流色谱(HSCCC)法分离制备红葡萄皮中花色苷单体的方法。以乙腈-正丁醇-甲基叔丁基醚-水-三氟乙酸(1∶40∶1∶50∶0.01, V/V)为溶剂体系,上相（有机相）为固定相,下相（水相）为流动相,流速为2.0 mL/min,转速为950 r/min,进样量为200 mg,分离得到的组分利用紫外-可见（UV）光谱和液质联用（HPLC-MS）技术进行定性分析。结果表明,经过一次高速逆流分离即可得到3种花色苷单体,分别为飞燕草色素-3-O-葡萄糖苷、锦葵色素-3-O-葡萄糖苷和芍药色素-3-O-葡萄糖苷,高效液相色谱（HPLC）峰面积归一法计算其纯度分别为93.7%、95.2%、91.6%。采用高速逆流色谱法成功从红葡萄皮中一次性分离得到3种高纯度的花色苷单体,其中芍药色素-3-O-葡萄糖苷为首次分离得到。     

Phenolic compounds and antioxidant properties of different grape cultivars grown in China

Skins and seeds of 18 grape cultivars belonging to Oriental and North American Vitis Species/hybrids, and Vitis vinifera were analysed for health beneficial properties. Four phenolic compound parameters (total phenols, flavonoids, flavan-3-ols and anthocyanins) and three antioxidant property parameters (DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, ABTS [2,2-azino-di-(3-ethylbenzothialozine-sulphonic acid)] radical scavenging and FRAP (ferric reducing antioxidant power)) were measured. Principal component analysis (PCA) was used for this evaluation and results showed that both phenolic compounds and antioxidant properties in the seeds and skins varied among the cultivars investigated. V. vinifera “Cabernet Sauvignon” had the highest values of phenolic compounds and antioxidant properties in seeds followed by Muscadines, while the lowest appeared in the Oriental Vitis species. As expected, these values of the Euro-Asian or Euro-American hybrids fell between the parents. However, far less variation of these values was observed in the skins among different grape cultivars investigated. Interestingly, even the total phenolic contents in the berries of two cultivars are similar, distributions of phenolic compounds in seeds and skins varied greatly among them. Additionally, significant correlations among different antioxidant assays in both seeds and skins were observed. These antioxidant properties were also found highly correlated to the main phenolic compounds.     

A comparative study to distinguish the vineyard of origin by NIRS using entire grapes,skins and seeds

BACKGROUND: Interest in high‐quality products with a clear geographical origin is increasing. For the wine industry and market sector, identity preservation is of fundamental importance owing to the large number of geographical classifications. Nowadays, there is a growing demand for analytical methods for tracing grapes and wines. In the oenological sector, infrared spectroscopy is becoming an attractive tool allowing simultaneous measurement of several analytical parameters and enabling real‐time decision making. RESULTS: Discriminant partial least squares, a supervised pattern recognition technique, was employed to discriminate between vineyards of origin using the near‐infrared spectra of intact grapes, skins or seeds. In order to compare the three sample presentations, a receiver operating characteristic curve was used. The best results were obtained using intact grape seeds, with prediction rates of samples correctly classified of about 95%, although the good results obtained with entire grapes (about 93% of samples correctly classified) and the simplicity of use of the fibre optic probe could advise using entire grape presentation for comprehensive studies. CONCLUSION: The procedure reported here seems to have excellent potential for a fast and reasonably inexpensive analysis of the origin of samples. It is noted that such classification can be made at any time of ripening. This paper provides information of interest to develop new and extensive models in the future. © 2012 Society of Chemical Industry     

Pre-bottling use of dehydrated waste grape skins to improve colour,phenolic and aroma composition of red wines

Different dehydrated waste grape skins from the juice industry were added into aged and young red wines as an innovative way of compensating for colour loss before bottling. After addition of grape skins, colour intensity of wines increased a mean 11% and a maximum of 31% with predominance of the red component. Total polyphenols mean increase was 10% with a maximum value of 20%. Analysis of low molecular weight phenolic compounds by HPLC–DAD showed a significant (p < 0.05) content increase of the bioactive compounds gallic acid, (+)-catechin, (−)-epicatechin, and (E)-resveratrol. Anthocyanins content also increased at an average of 50 mg/l. The volatile profile of wines analysed by SBSE–GC–MS was only moderately influenced by the treatments. Mixtures of dehydrated waste grape skins were useful to improve the colour and polyphenol profile of red wines, considering them a useful tool for correcting colour loss before bottling.     

近红外光谱法快速测定烟草中的总挥发酸与总挥发碱

应用傅立叶变换近红外光谱法测定730个具有代表性的烟草近红外光谱数据,采用偏最小二乘回归建立了近红外光谱信息与其含量之间的定量校正模型,并对50个验证样品进行预测验证。总挥发碱和总挥发酸的预测标准差(RMSEP)分别为0.020和0.009,验证样品的相对标准偏差各为1.120%和0.919%。