First confirmation in red wine of products resulting from direct anthocyanin–tannin reactions

Analysis of wine fractions before and after thiolysis confirmed the occurrence in red wine of direct reactions between anthocyanins and tannins established earlier in model solutions. Results showed the presence of two types of structures differing in the linkage position of the anthocyanin moiety. On one hand, detection of malvidin‐3‐glucoside (Mv3g) among thiolysis products revealed the presence of anthocyanin‐derived pigments in which Mv3g is linked by its C‐6 or C‐8 top. On the other hand, LC/MS analysis allowed the detection of two derivatives tentatively identified as flavenes or a bicyclic condensation products yielded by the reaction of a flavanol monomer (C‐6 or C‐8 top) with malvidin‐3‐glucoside (C‐4 position). The presence of the corresponding benzylthioethers after thiolysis of the polymeric fractions confirmed that procyanidins are similarly involved in the latter reaction. Besides, MS also allowed the detection of new benzylthioethers of catechin derivatives released after thiolysis of the wine fractions, indicating that in addition to the postulated processes other types of reactions take place in wines. © 2000 Society of Chemical Industry     

Development changes of anthocyanins in Vitis vinifera grapes grown in the Douro Valley and concentration in respective wines

Grapes of Touriga Nacional and Touriga Francesa red Vitis vinifera varieties have been sampled from two vineyard sites at different altitudes during three consecutive vintage years (1997, 1998 and 1999) in the Douro Valley. The total anthocyanidin monoglucosides (AMGs) detected by HPLC/DAD and the red colour of grape skin extracts were monitored during the last month of maturation. Microvinifications were performed with the grapes studied and the resulting Port wines were analysed. Malvidin 3‐glucoside and its acylated esters were the major AMGs irrespective of cultivar at harvest date. Vineyard altitude, together with other variables, was found to be an important factor contributing to the amount of anthocyanin compounds found in grapes of Touriga Nacional and Touriga Francesa. Overall, the climatic conditions observed at higher vineyard sites appeared to be advantageous, resulting in larger amounts of AMGs in grapes. The same outcome was obtained in the resulting wines, which showed higher levels of AMGs when made from grapes grown at higher altitude, especially for Touriga Francesa. © 2002 Society of Chemical Industry     

Flavonol composition of Australian red and white wines determined by high‐performance liquid chromatography

Background and Aims: Flavonols are present in Vitis vinifera L. wine grapes as glycosides and are found in wines in both their glycosidic and aglycone forms. Flavonols and their glycosides are important components in wine because of their impact on colour, taste and health properties. An assessment of the flavonols and flavonol glycosides present in a wide selection of Australian red and white wines (n = 121 and 44, respectively) was undertaken. Methods and Results: Analyses were performed using HPLC, with compound identification being aided by HPLC‐MS. In the red wines, quercetin and myricetin dominated the flavonol profile, and quercetin‐3‐glucuronide was by far the most abundant glycoside present. White wines had considerably lower levels of flavonols and their glycosides, in most cases, being below the detection limit of the HPLC method. Conclusions: There appeared to be no correlation between the flavonol profile and wine variety or region in either white or red wines. Contrary to literature reports of rutin in wine, rutin was not found in any of the wines we analysed, and spiking experiments showed rutin rapidly degraded to the aglycone quercetin. Furthermore, changes in elution order for some quercetin glycoside standards were observed depending upon the acid used in the mobile phase. Significance of the Study: This is the first time the flavonol contents of an extensive cross section of Australian wines have been reported. The concentrations are consistent with those reported in wines from other countries. In light of the instability of rutin in wine, critical review should be given to reports discussing its presence.     

Oak‐matured wines: influence of the characteristics of the barrel on wine colour and sensory characteristics

The influence of oak origin (French or American oak), volume (220, 500 and 1000 l barrels) and age of the barrel (new or used) on the colour and sensory characteristics of a red wine, after 6 months of maturation, was studied. The colour of the wines is characterized by the red, yellow and blue percentages, total polyphenols index, free anthocyanins, polymeric anthocyanins, colour density, hue, tannin content and HCl index. The results of a multivariate analysis of variance showed that colour evolution is faster in small, new American barrels than in large, used barrels or in French barrels. This evolution towards a more stable colour is manifested by a higher content of polymeric anthocyanins, hue and HCl index and lower percentage of red colour. The sensory analysis also reflects these results: the samples obtaining higher scores, at this stage of maturation, are those aged in small, new American barrels. Copyright © 2003 Society of Chemical Industry     

Antioxidant potential of single-variety red wines aged in the barrel and in the bottle

Wine constitutes a dynamic system in continuous evolution, in which numerous reactions involving polymerization and condensation take place between its phenolic compounds during the ageing process, which undoubtedly affect its structure and, very probably, its antioxidant effect. This study set out to evaluate the effect of ageing on the antioxidant potential of wine. A group of 162 wines were studied, of varying ages, which had undergone different ageing processes, both in the barrel and in the bottle, and which were prepared from different grape varieties and vintages. Total antioxidant capacity (ABTS, DPPH, DMPD, ORAC and FRAP), scavenger activity (HRSA and SRSA) and the biomarkers of oxidative stress (DNA-damage and ABAP-LP) were all analysed. The assay methods showed different behaviours for the same wines, thus the young wines presented higher indices for ABTS, DPPH and DMPD, whereas those that were aged showed higher indices for ABAP-LP and ORAC. Finally, the antioxidant potential of the wines in the study appeared not to be influenced by other factors, such as microoxygenation or grape variety.     

Simultaneous Determination of 15 Phenolic Constituents of Chinese Black Rice Wine by HPLC‐MS/MS with SPE

This study established a new method for quantitative and qualitative determination of certain components in black rice wine, a traditional Chinese brewed wine. Specifically, we combined solid‐phase extraction and high‐performance liquid chromatography (HPLC) with triple quadrupole mass spectrometry (MS/MS) to determine 8 phenolic acids, 3 flavonols, and 4 anthocyanins in black rice wine. First, we clean samples with OASIS HLB cartridges and optimized extraction parameters. Next, we performed separation on a SHIM‐PACK XR‐ODS column (I.D. 3.0 mm × 75 mm, 2.2 μm particle size) with a gradient elution of 50% aqueous acetonitrile (V/V) and water, both containing 0.2% formic acid. We used multiple‐reaction monitoring scanning for quantification, with switching electrospray ion source polarity between positive and negative modes in a single chromatographic run. We detected 15 phenolic compounds properly within 38 min under optimized conditions. Limits of detection ranged from 0.008 to 0.030 mg/L, and average recoveries ranged from 60.8 to 103.1% with relative standard deviation ≤8.6%. We validated the method and found it to be sensitive and reliable for quantifying phenolic compounds in rice wine matrices.     

不同品种蓝莓酒抗氧化能力及其多酚含量分析

本实验对6个不同品种的蓝莓酒的总酚、总类黄酮、原花青素、总花色苷和总抗氧化能力及其相关性进行了分析,结果发现,不同品种的总酚、总类黄酮、原花青素、总花色苷和总抗氧化能力变幅和变异系数较大,存在显著差异(p＜0.05);蓝莓酒总抗氧化能力与总酚、总类黄酮、原花青素和总花色苷含量之间存在显著性的相关性(p＜0.01),其中与原花青素的相关性最强,达到0.898.     

Rapid determination of ethyl carbamate in Chinese rice wine using headspace solid‐phase microextraction and gas chromatography–mass spectrometry

Ethyl carbamate (EC) is a naturally occurring toxic contaminant that may imply a risk to human health and is usually found in alcoholic beverages such as Chinese rice wine. An automated procedure for the rapid determination of EC in Chinese rice wine was developed by headspace solid‐phase microextraction (HS‐SPME) coupled to gas chromatography–mass spectrometry (GC‐MS). Using propyl carbamate as internal standard, the optimized HS‐SPME sampling with a polyacrylic fibre was 45 min at 70°C after applying 38.8% NaCl to saturate the sample. This method showed good linearity over a range of 25–600 µg L^?1 (R² = 0.997). The recovery, relative standard deviation and limit of detection were 90.21–97.35%, lower than 2.89% and 1.19 µg L^?1, respectively. Additionally, the ethanol concentration had no effect on the analysis of EC. The total analysis time of 57 min per sample in continuous determination was twice as fast as the widely used solid‐phase extraction–GC‐MS method. This solvent‐free HS‐SPME‐GC‐MS procedure is suitable for the rapid, automated, and therefore convenient, determination of EC in Chinese rice wine. Copyright © 2012 The Institute of Brewing & Distilling     

Proximate composition and sensory evaluation of anthocyanin‐rich purple sweet potato (Ipomoea batatas L.) wine

Purple sweet potato (PSP) is a special type of sweet potato having high anthocyanin pigment in the root. The starch contents of PSP (root/water homogenised in 1:1 ratio) were enzymatically saccharified [using commercial thermostable enzymes Termamyl^® (0.2%) and Dextrozyme^®GA (1%)] to fermentable sugars, and the filtrate was ameliorated with cane sugar to achieve 20° Brix, for subsequent fermentation into a red wine using 2% yeast (Saccharomyces cerevisiae) as starter culture. The wine had the following proximate compositions: total soluble sugar (TSS), 2.25° Brix; starch, 0.15 g per 100 mL; total sugar, 1.35 g per 100 mL; TA, 1.34 g tartaric acid per 100 mL; phenol, 0.36 g (caffeic acid equivalent) per 100 mL; anthocyanin, 55.09 mg per 100 mL; tannin, 0.64 mg per 100 mL; lactic acid, 1.14 mg per 100 mL; ethanol, 9.33%(v/v); and pH, 3.61. 2, 2‐Diphenyl‐1‐picrylhydrazyl (DPPH) scavenging activity of the wine was 58.95% at a dose of 250 μg mL^?1. Principal component analysis reduced the eleven original analytical and proximate variables (TSS, starch, total sugar, TA, phenol, anthocyanin, tannin, lactic acid, ethanol, pH, DPPH) to four independent components, which accounted for 76.65% variations. Sensory evaluation was carried out by sixteen trained panellists on various attributes such as clarity, colour, viscosity, odour, flavour, spritz and finish. Independent ‘t’ test confirmed that all the sensory attributes of the PSP wine scored closely (within 10% variation) to that of a commercial grape wine. The red wine produced contains essential antioxidants and acceptable sensory qualities.     

Study and quantification of monomeric flavan‐3‐ol and dimeric procyanidin quinonic forms by HPLC/ESI‐MS. Application to red wine oxidation

Monomeric flavan‐3‐ols and dimeric procyanidins of red wine were oxidised by two processes, chemical and enzymatic. Unstable quinonic forms were stabilised by sulphonation, and the resulting sulphones were quantified by coupled HPLC/ESI‐MS. The effects of temperature and UV light on the oxidation of phenolic compounds were also investigated. The concentration of quinones increased with increasing temperature, but the kinetics of the reaction was independent of temperature. Likewise, more quinones were formed in the presence of UV light than in its absence, but UV light also did not affect the kinetics of the reaction. Thus temperature and UV light affect the quantity of quinones formed but not the rate at which they appear. © 2001 Society of Chemical Industry     

Comparative study of browning and flavan‐3‐ols during the storage of white sherry wines treated with different fining agents

White sherry wines were treated with three fining agents (activated charcoal, PVPP and Riduxhigh), in addition to an initial treatment with casein and bentonite, in four different combinations. The wines were stored at 20 or 30 °C for 1 year with a view to examining changes in their flavan‐3‐ol fraction and differences in their degree of sensitivity to browning. Flavan‐3‐ol monomers and dimers, as well as browning measured as absorbance at 420 nm, increased during storage in all the wines. After this period the wines treated with fining agents containing activated charcoal, PVPP and Riduxhigh exhibited less marked browning, with no significant differences among them at both 20 and 30 °C. However, taking into account the higher initial colour of bottled wines treated with Riduxhigh in relation to those treated with activated charcoal or PVPP, this fining agent showed higher capacity to control browning. © 2000 Society of Chemical Industry     

Characterization of Volatile and Semi‐Volatile Compounds in Chinese Rice Wines by Headspace Solid Phase Microextraction Followed by Gas Chromatography‐Mass Spectrometry

The volatile and semi‐volatile compounds of Chinese rice wines were extracted by headspace solid phase microextraction (HS‐SPME) and analyzed by gas chromatography‐mass spectrum (GC‐MS). The original Chinese rice wine samples were diluted with deionized water to a final concentration of 6% (v/v) ethanol and then extracted by HS‐SPME. The samples were pre‐equilibrated at 50°C for 15 min and extracted with stirring at the same temperature for 45 min prior to injection into a GC‐MS. A total of 97 volatile and semi‐volatile compounds were identified from ten Chinese typical rice wine samples, including 13 alcohols, 8 acids, 28 esters, 4 aldehydes and ketones, 17 aromatic compounds, 3 lactones, 6 phenols, 3 sulphides, 9 furans and 6 nitrogen‐containing compounds, of which, 39 compounds were firstly reported in Chinese rice wine. By stepwise linear discrimination analysis, the ten Chinese rice wine samples could be classified into three groups according to the production area, and in particular, the production technologies.