Ochratoxin A: an improvement clean-up and HPLC method used to investigate wine and grape juice on the Polish market.

A routine method appropriate for the determination of ochratoxin A (OTA) in wine, grape juice and grape juice drinks was described, and the occurrence of the mycotoxin was investigated in the most popular red wines, grape juice and grape juice drinks available on the Polish market. After clean-up on immunoaffinity column, samples were analysed by RP-HPLC using a fluorescence detector at 330 and 460 nm. The average OTA recoveries from spiked blank wine samples varied from 60 to 82%, and RSD% ranged from 5 to 14%. The OTA recovery for spiked grape juice and grape juice drinks were 80-100%, but the RSD% was between 7 and 10%. The limit of detection and limit of quantitation for all sample types were 0.5 and 2.0 ng l(-1), respectively. Fifty-three samples of red wine and seven samples of grape juice and grape drinks were assessed by means of this analytical procedure. OTA was detected in most wine samples (92%); its concentrations ranged from 2.2 to 6710 ng l(-1). In all grape juice and drink samples, OTA levels ranged from 1.6 to 64.7 ng l(-1).     

Optimisation of the Amido Black assay for determination of the protein content of grape juices and wines

While the heat/chill stability of white wines cannot be predicted from the total protein concentration, this information is useful in assessing the effectiveness of fining treatments. We have adapted the Amido Black assay for use in grape juice and wine. The response of bovine serum albumin (BSA) was similar in water, model wine and model juice. The linear range of the assay (<100 mg l^?1) extends beyond protein concentrations typically found in grape juices and wines. The limit of quantification was 11.1 mg l^?1 for BSA in model wine and 7.6 mg l^?1 in model juice, while the limit of detection was found to be less than 3 mg l^?1 in either solution. In contrast to other methods of protein determination, this assay is not affected by common wine phenolic and pectic compounds or by glutathione. The mean response of BSA was similar in model juice and red and white grape juices. The mean response of BSA in red wine was lower than in white wine and model wine (p < 0.001), and there was considerable variation in response among wines. Protein concentrations determined using this method were reproducible (CV < 10%). This optimised assay can be used to monitor protein levels in grape juices and wines. © 2001 Society of Chemical Industry     

Ochratoxin A in wine and grape juice sold in Canada.

Ochratoxin A (OTA) was determined in 251 samples of wines and grape juice collected over 3 years in Canada. In total, 25/84 samples of red wine, 22/96 samples of white wine, 3/46 red grape juices and 1/25 white grape juices contained OTA levels above the limit of quantitation (LOQ). Canadian wines, when compared with imported products, showed both a lower OTA occurrence, noted as positive (19 versus 48% above the limit of detection (LOD) for wines), and a lower level of OTA contamination (upper bound mean of 17.5 versus 163pg ml(-1) for wines). Wines from the USA contained no quantifiable levels of ochratoxin A. OTA was found in Canadian and US grape juice samples, with 12.9% above the LOD and an upper bound mean of 13.3pg ml(-1). It was extracted from a wine or grape juice sample by passing it through an immunoaffinity column. The sample matrix was washed off the column with water. OTA was eluted from the column with methanol and quantitatively determined by liquid chromatography using a fluorescence detector. The presence of OTA was confirmed by esterification with boron trifluoride-methanol. The LOQ of OTA was estimated as 20 pg ml(-1) in white wine (S/N 10:1) and 40 pg ml(-1) in red wine, white grape juice and red grape juice (S/N 20.1). The LOD was estimated as 4pgml(-1) for white wine and 8pgml(-1) for red wine and white and red grape juices (S/N 3:1).     

Simple determination of main organic acids in grape juice and wine by using capillary zone electrophoresis with direct UV detection

An accurate, simple and rapid capillary zone electrophoresis (CZE) method with direct UV detection has been set up for the determination of main organic acids in grape juice and wine. The determination of tartaric, malic, and citric acids in grape juices and tartaric, malic, succinic, acetic, lactic and citric acids in wines can be achieved in less than 3 min with only a simple dilution and filtration treatment of the sample. Validation parameters of the method as detection and quantification limits, linearity, precision (intraday and interday analysis) and recovery were also studied in grape juice, white wine, rose wine and red wine, separately. The proposed method decreases the analysis times of the previous reported CZE methods and allows the rapid control of the grape maturity, the winemaking processes and the detection of wine alterations and/or illnesses.     

Determination of mepiquat chloride in grape, wine and juice by liquid chromatography with electrospray tandem mass spectrometry

A simple and rapid method was developed for the analysis of mepiquat chloride in grape, wine and juice by high-performance liquid chromatography with electrospray tandem mass spectrometry (LC/MS/MS). Mepiquat chloride was extracted with water-methanol (1:1). Extracted solution was adjusted to pH 10 with ammonia solution. A part of the extracted solution was cleaned up on a styrenedivinylbenzene (SDVB) cartridge for LC/MS/MS. The LC separation was performed on a C18 column (50 mm x 2 mm i.d.) using 0.1% IPCC-MS7-methanol (60:40) as the mobile phase at a flow rate of 0.2 mL/min. The mass spectral acquisition was done in the positive ion mode by applying selected reaction monitoring (SRM). The recoveries of mepiquat chloride from fresh grape, wine and juice fortified at 5 microg/kg and 50 microg/kg were 84.5-96.1%. The lower limit of quantification was 1 microg/kg. Fourteen fresh grape samples, 14 wines (white), 36 wines (red) and 11 juice samples were analyzed by this method. Mepiquat chloride was detected in 5 fresh grape samples, 3 wines (white) and 1 wine (red) at the level of 12.8-199 microg/kg, 5.7-47.7 microg/kg and 24.1 microg/kg, respectively.     

13C NMR spectroscopic determination of diethyleneglycol in wine

A procedure for the structure specific determination of diethylene glycol from wine is described. The analysis can be performed without pretreatment of the samples. The detection limit is 10 mg/l.     

Statistical optimization of ethanol fermentation parameters for processing local grape cultivars to wines

Grape juice from two local grape cultivars viz. Punjab MACS purple and H‐144 was subjected to prefermentation skin treatment. Ethanol fermentation w.r.t agitation rate, temperature, inoculum size, and nutrient supplementation were optimized using Triple M medium following response surface methodology (RSM). RSM results were numerically optimized keeping temperature “in range” for red wine and “low” for white wine which showed agitation rate of 80 ± 1 rpm for 24 hr, diammonium hydrogen orthophosphate supplementation @ 150 mg/100 ml, inoculum size of 6.1 and 6.5% (vol/vol), and fermentation temperature of 24.6 and 21 °C as optimum for ethanol fermentation of red and white wines, respectively. Optimized results were validated on grape juice of Punjab MACS purple and H‐144 cultivars that lead to 12.0 and 11.2 (%vol/vol) ethanol production, respectively. Gas chromatography mass spectrometry analysis revealed the presence of 41 volatile compounds in the form of phenols, alcohols, terpenes, esters, ketones, and amines that add to the nutraceutical and antioxidant value of the wines.

Practical applications

Present study provides the statistical optimized fermentation parameters for red and white wine production separately. Optimization of an efficient processing technology to produce local grape wines will help to reduce the price of wines so that they are available to common masses at affordable costs besides improving the economic status of grape growers in the state and providing valuable information to wine makers to establish winery under North Indian conditions. Use of synthetic grape juice (Triple M media; during off season of grapes) lead to optimization of ethanol fermentation parameters in two separate fashions considering fermentation temperature as key parameter. Gas chromatography mass spectrometry analysis showed the presence of flavonoids, terpenes, and esters increasing nutritive value of product, providing antioxidants to the consuming person.     

Occurrence of ochratoxin A in wine and grape juice marketed in Rio de Janeiro, Brazil.

Ochratoxin A (OA) is receiving attention world-wide because of the hazard it poses to human health. The aim was to test the distribution of OA in grape juice, pulps of frozen grapes, and national and imported table wine obtained from markets in Rio de Janeiro, Brazil. Analytical methodology using immunoaffinity column for OA extraction and clean-up with a final separation on a reversed-phase (C(18)) column and fluorescence detection in high-performance liquid chromatography showed a detection limit of 21 ng l(-1). The mean recovery was 91% for red wines and 82% for white wines; while the mean recoveries for juices and pulps of frozen grapes were 91.6 and 88%, respectively. Of 64 samples of grape juice and frozen pulps, 25% were positive for OA, being the mean content of 37 ng l(-1) with a maximum concentration of 100 ng l(-1). In wines, the mean concentration detected in 80 samples analysed was 34.4 ng l(-1) with 28.75% of positive samples. Red wines showed the highest percentages and levels of contaminated samples: 38% and 37 ng l(-1), respectively. The white wine contained levels above 26 ng l(-1) in 17.75% of the analysed samples. The levels of contamination detected in red wine sold in Río de Janeiro were not enough to surpass the virtually safe dose established as 5 n g kg(-1) body weight of daily intake.     

红提葡萄不同发酵阶段功能性及抗氧化性研究

为研究红提葡萄在不同发酵阶段的品质变化,提高红提葡萄的产品价值,文章采用功能性成分和抗氧化能力的测定方法,结合主成分分析,对红提原汁、果酒和果醋的功能性成分(VC、花色苷、总酚和总黄酮)和抗氧化能力(总抗氧化能力、还原能力、DPPH、ABTS和羟自由基)进行测定分析。结果显示:红提原汁、果酒和果醋三者的功能性成分含量有较大的差异,其中红提果醋的总酚和总黄酮含量较高(总酚8.5mg/dL、总黄酮30mg/dL),造成这种差异可能是不同发酵阶段的菌种不同所引起的;在抗氧化性方面,红提果醋具有较高的抗氧化能力。该研究对红提葡萄不同发酵阶段产生的变化进行了分析,为不同加工过程的品质变化提供了依据。     

Determination of molecular and free sulphur dioxide in foods by headspace gas chromatography

A study was made of the equilibria between SO2 in packaged liquid foods and gaseous SO2 in their headspace atmospheres as a basis for a new analytical method for the determination of molecular and free SO,. Using a gas-chromatographic method developed previously to determine SO2 at the 1 × 10⁻³ mg/l level in atmospheres saturated with water vapour, studies with aqueous solutions showed that headspace SO2 was directly proportional to molecular SOz in accordance with Henry's law.
Using the Henry's law constant for the S02/H20 system, determinations of molecular SOz were made on a white and a red wine and a fruit juice, each adjusted to five levels of pH to achieve different concentrations of molecular SO,. The results observed by the headspace method showed good agreement with those determined by a reference analytical method with white wine and fruit juice, but with red wine the reference method gave values which were more than 45% higher. Free SO2 was determined in a range of white wines by the headspace and reference methods, and the results showed high correlations.
The headspace method is rapid, precise and non-destructive. A major advantage is that, during the analysis, it does not change the complicated equilibria between SO, and its ionised species, hence complexes of SO2 and food constituents are not disturbed.     

Occurrence and stability of inorganic and organic arsenic species in wines, rice wines and beers from Central European market

We investigated in total 80 wine samples of different types and seven grape juice and 23 beer samples purchased from markets in Central Europe in order to understand the arsenic (As) speciation and help assess the potential As toxicity via intake of alcoholic beverages. Generally, total As concentrations in most samples investigated were below the drinking water limit 10 μg l(-1) published by the World Health Organization (WHO); ranging from 0.46 to 21.0 μg l(-1) As in red and white wines and from 0.75 to 13.4 μg l(-1) As in beers. In addition, concentrations of total As in rice wine and in rice beer were 0.63-6.07 and 3.69-8.23 μg l(-1) As, respectively. The total As concentrations in ice wine ranged from 7.94 to 18.8 μg l(-1) As, significantly higher than in white and red wine. Arsenite predominated as the As species in most of the wine samples, whereas arsenate was the dominant species in rice wine, beer and rice beer. Methyl As components were usually minor components in all wine and beer samples. Monomethylarsonic acid, dimethylarsinic acid and two additional unknown As species were frequently found in grape juice, late harvest and ice wine with higher sweetness. After air exposure, arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid were stable at 4°C for months, probably due to the acidic conditions of wine and beer samples. The presence of sulfite had little influence on As speciation in wine. Despite the predominance of more toxic arsenite and arsenate in wine and beer, the estimated weekly exposure to As (via consumption of beer, wine and rice wine) is low. The As intake per capita is 6.81 μg from beer, <1.93 μg from wine and 0.88 μg from rice wine, estimated using the median of total As concentration multiplied by the average consumption per capita of the corresponding beverage.     

气相色谱指纹图谱法快速鉴别红葡萄酒真假

通过采集10个常见葡萄酒产地中85份真红葡萄酒样品的气相色谱指纹图谱,利用中药色谱图分析和数据管理系统软件进行识别分析,建立了红葡萄酒的气相色谱指纹图谱鉴别葡萄酒真假方法。结果表明,该方法过程仪器的精密度和方法的重现性很好,真红葡萄酒标准指纹图谱包括12个特征色谱峰,其气相色谱指纹图谱峰面积相关系数法、峰面积夹角余弦法、全图谱相关系数法和全图谱夹角余弦法的相似度阈值为≥0.9700。3种方式勾兑的假葡萄酒的试验表明,掺水稀释葡萄酒峰面积的相关系数法和夹角余弦法相似度值都在0.1700以下;葡萄汁勾兑葡萄酒峰面积相关系数法和夹角余弦法相似度值在0.6128以下;人工色素勾兑假葡萄酒峰面积相关系数法和夹角余弦法的相似度值在0.1001以下。通过市售2种可疑葡萄酒的验证试验表明,该2种可疑葡萄酒的峰面积相关系数法和夹角余弦法的相似度值在0.1500以下,低于真红葡萄酒的相似度阈值;且缺少红葡萄酒具有的特征色谱峰,可确定为假葡萄酒。本方法操作简便、快速、客观、准确,是一种值得推广应用的葡萄酒真假的鉴别方法。     

13C NMR-spektroskopische Bestimmung von Diethylenglykol im Wein

Zusammenfassung Es wird eine strukturspezifische (¹³C NMR-Spektroskopie) Bestimmung von Diethylenglykol direkt aus Wein ohne Probenvorbehandlung beschrieben. Die Nachweisgrenze liegt bei 10 mg/1.

---

Determination of diethylene glycol in wine with¹³C NMR- spectroscopy

Summary A procedure for the structure specific determination of diethylenglycol from wine is described. The analysis can be performed without pretreatment of the samples. The detection limit is 10 mg/l.

     

响应面法优化黑枸杞-葡萄复合果酒发酵工艺的研究

以黑枸杞汁和葡萄汁为原料,考察酵母添加量、发酵温度和初始糖度对复合果酒的品质的影响。在单因素试验结果的基础上,采用响应面法优化黑枸杞-葡萄复合果酒的发酵工艺参数。结果表明,黑枸杞汁与葡萄汁的最佳配比为7∶3（V/V）,最佳发酵工艺条件为发酵温度20 ℃、酵母添加量0.03%、初始糖度24%。在此条件下,发酵所得复合果酒酒精度为12.7%vol,感官评分为90分,果酒酒香浓厚,酒体澄清透明,呈酒红色。     

Enhancement of red wine colour by pre-fermentation addition of copigments

The effects of pre-fermentation additions of catechin and caffeic acid to musts were investigated. The cultivar Listan negro, a major red grape grown in the Canary Islands, was used for these studies. The addition of catechin at 120 mg/l resulted in only 10% enhancement in wine colour (AU at 520 nm) after fermentation, while caffeic acid, at the same level, enhanced the wine colour by 60%. These results appear to be the first report of such a significant increase in wine colour achieved by pre-fermentation treatments with natural grape constituents, supporting the view that red wine colour is generally limited by the levels of cofactors for copigmentation rather than by the level of anthocyanins alone. This demonstrates the importance of non-pigment composition in establishing red wine colour and the influence of initial must composition.     

Cell-recycle membrane bioreactor for conducting continuous malolactic fermentation

A cell-recycle membrane bioreactor system has been evaluated for conducting rapid, continuous malolactic conversion in wine. A reactor (300 mL) containing 10¹⁰ cfu/mL of Leuconostoc oenos and operating at a flow rate of 6 mL/min for periods up to 56 h gave greater than 95% degradation of L-malic acid in a range of red and white wines. Stability of malic acid degrading activity and long term performance of the reactor varied with strain of Leuc. oenos , wine being processed and temperature. Increasing operating temperature from 20°C to 30°C caused rapid loss of activity. When grape juice was processed, reactor performance (>95% degradation of malic acid) was stable for at least 125 h. Addition of 10% ethanol to the juice caused a loss in reactor activity. Some off-flavours were acquired by the wine during processing in the reactors, but this problem was minimised by using reactors containing a mixture of cells of Leuc. oenos and Saccharomyces cerevisiae .     

Mousy off-flavour production in grape juice and wine by Dekkera and Brettanomyces yeasts

The ability of four known species of Dekkera and Brettanomyces yeasts to produce mousy off-flavour in grape juice and wine was investigated for the first time. Using a sensory assessment technique the twelve type strains of Dekkera and Brettanomyces , representing four species, were found to grow and to be capable of producing mousy off-flavour in a grape juice medium; however, differences between strains were apparent. Four strains representing the two species of Dekkera (D. bruxellensis and D. anomala ) known to be associated with the spoilage of wine and other fermented beverages were further investigated for mousy off-flavour production in a red and white wine supplemented with nutrients. D. anomala and only one of the three D. bruxellensis strains tested grew in both wines and generally produced a moderate level of off-flavour, whereas the remaining two strains of D. bruxellensis , despite slowly losing viability (10- to 100-fold) over the 52–55 day period, produced detectable off-flavour. This work demonstrates the general ability of Dekkera and Brettanomyces yeasts to produce mousy off-flavour and confirms the importance of these yeasts for off-flavour production in grape juice and wine.     

Physico-chemical properties of cell wall materials obtained from ten grape varieties and their byproducts: grape pomaces and stems

The availability and the potential of wine by-products, grape pomaces and stems, obtained from ten different grape (Vitis vinifera L.) varieties (six red and four white) as raw materials for the production of dietary fibre (DF) concentrates were evaluated. The overall chemical composition, carbohydrate analysis and functional properties of DF from fresh grapes, grape pomaces and stems from those grape varieties were analysed. Both winemaking by-products presented considerable quantities of DF, ranging from 60% to 90% of total dry matter. The cell wall polysaccharides (CWP) composition of grape pomaces and fresh grapes was rather similar, pectic substances being the main component of the cell walls (40–54% total CWP). In contrast, cellulose was the predominant cell wall polymer for the stems (40–49% total CWP). In addition, the pectin content of grape pomaces exhibited significant differences between red and white grape varieties. The degree of methyl-esterification of uronic acids from wine by-products ranged from 21 to 39%; thus, pectic polysaccharides from the different samples could be classified as low methyl-esterified pectins. Klason lignin accounted for around 20–25% of DF in both grape pomaces and stems. With regard to the potential incorporation of DF concentrates into the food chain, functional properties were also determined. Swelling, water and fat retention capacity results showed great variability depending on the grape variety analysed.     

Response surface methodological study on HMF and fluorescent accumulation in red and white grape juices and concentrates

White and red grape juices and their concentrates were subjected to thermal treatments at different temperatures ranging from 50 to 70 °C at different times. 5-Hydroxymethylfurfural (5-HMF) and fluorescence relative index (FLRI) were measured. Response surface methodology (RSM) was applied to determine the effect of temperature and time on the HMF and FLRI formation at the different Brix (bx) degrees. An increase in temperature (from 50 to 70 °C) and time (from 12 to 192 h) for 15°, 45° and 65° Brix degrees was associated with an increase in HMF and FLRI development of white and red grape juices. HMF formation was higher in white grape juice and concentrates than in red ones. Optimum conditions were confirmed and these fitted the experimental data well. Thus, regression equations can be used to estimate HMF and FLRI values at various Brix degrees for white and red grape juices and concentrates.     

Treatment of Grape Juice by Osmotic Evaporation

ABSTRACT: Osmotic evaporation (OE) was applied to grape juice to increase the sugar content and thus to improve the quality of wine obtained after fermentation. The use of aqueous solutions of glycerol as extractant avoids corrosion and scaling, which are the main problems in OE with brines. Preliminary experiments were performed on lab scale using water or glucose solutions as feed, and NaCl or glycerol as extractant. The runs with NaCl allowed measurement of the membrane transport properties, whereas glycerol was used to quantify the concentration polarization phenomena involved. The extract side concentration polarization severely limited the flux achievable for glycerol concentration above 50% wt, while the extract side concentration was negligible in the OE with NaCl. The feed side concentration polarization played a minor role for glucose content up to 40% wt. Experiments with grape juice were performed on pilot scale equipped with plate and frame modules. The performance were in good agreement with lab results on glucose model solutions, the lower flux observed was due only to the low temperature of operation. The process was tested on 3 types of grape juice (white, rosé, and red). Treated and control juices were fermented, and corresponding wines were analyzed for selected parameters and evaluated by sensory analysis. The OE treatment removed water from grape juice and increased both the total soluble solids and sugar content of juice, thus ethanol content and dry extract in wine always increased. The osmotic evaporation significantly improved sensory quality of red wine that was judged as having a full body, more structure, and persistence.