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).     

Red clover isoflavonoids as anthocyanin color enhancing agents in muscadine wine and juice

Isoflavonoid extracts from red clover (Trifolium pratense) leaves were found to enhance overall color and stability of anthocyanin 3,5-diglucosides present in muscadine grape (Vitis rotundifolia) juice and wine through intermolecular copigmentation reactions. Predominant isoflavonoids present in red clover included formononetin, biochanin A, and prunetin and were the major polyphenolics identified to influence anthocyanin color and stability. Since red clover isoflavonoids have poor water solubility characteristics, this allowed for removal of extraneous non-isoflavonoid compounds using hot water and subsequent extraction with ethanol. Isoflavonoid solubility was evaluated as a function of ethanol concentration with recoveries up to 57% found in 20% solutions. Changes in maximum absorbance, total soluble phenolics, isoflavonoids, and anthocyanins were evaluated in muscadine juice and wine following the addition of isoflavonoid extracts with maximum color enhancement found at an anthocyanin to cofactor ratio of 1:8, after which their solubility was prohibitive. Additionally, dried leaves and ethanolic extracts of red clover were added prior to and following fermentation of muscadine wine (11% ethanol) stimulating the natural copigmentation that takes place during red wine fermentation and aging processes. Once fermentation was complete, finished wines were evaluated over a 9-week storage period at 20 and 37 °C. Despite low levels of isoflavonoids present, color improvement and anthocyanin stability was observed in the wines during storage. Little information is available on copigmentation reactions occurring in actual food systems, yet red clover isoflavonoids proved to be novel and effective color enhancing compounds when used in low concentrations in young muscadine wines.     

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.     

红提和糯米复合发酵葡萄酒工艺优化及香气成分分析

目的：通过添加天然外源糖提升鲜食葡萄酒品质。方法：以红提为原料,糯米糖化液为外源糖,进行复合发酵红提葡萄酒工艺优化并分析鉴定葡萄酒中香气成分。以发酵温度、糯米糖化液和红提体积比、酵母接种量、SO2添加量为单因素,以乙醇体积分数和花色苷为指标研究红提葡萄酒发酵工艺;在单因素试验基础上进行3因素3水平响应面试验优化最佳发酵工艺。结果：单因素试验表明SO2添加量80?mg/L、发酵温度20?℃、酵母菌接种量1?g/L、糯米糖化液和红提体积比1∶4为最适发酵条件;响应面法优化红提果酒最佳发酵工艺为发酵温度21?℃、酵母接种量1.2?g/L、SO2添加量84?mg/L、体积比1∶4,发酵7?d得到体积分数为12.7%的红提葡萄酒。气相色谱-质谱联用仪共鉴定出39?种挥发性化合物,其中醇类15?种、酯类15?种、酸类5?种、萜类2?种。香气活性值（odor activity value,OAV）分析表明,共有12 种香气物质的OAV较高,主要为β-大马士酮、己酸乙酯、辛酸乙酯、乙酸异戊酯、癸酸乙酯。结论：以糯米糖化液为外源糖,可提升红提葡萄酒的乙醇体积分数,同时该葡萄酒具备良好的口感及典型的葡萄酒风味。     

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     

干白葡萄啤酒的研究

利用优质大麦芽、大米、酒花、白葡萄为主要原料 ,经过葡萄的酒精发酵、陈酿 ,再参与啤酒发酵、贮藏过程 ,使产品即保留了传统啤酒的风格 ,又具备干白葡萄酒的特征 ,该产品新颖、独特 ,色、香、味具佳。此产品的开发 ,可充分利用啤酒厂与葡萄酒厂现有设备和我国丰富的葡萄资源 ,节约粮食 ,生产高档啤酒。开拓了啤酒与葡萄酒生产的新途径     

葡萄酒及葡萄皮渣提取物抑制乙酰胆碱酯酶活性研究

建立乙酰胆碱酯酶抑制剂体外筛选模型,对不同的葡萄酒及葡萄皮渣提取物等19种样品进行了乙酰胆碱酯酶活性抑制作用的研究。结果显示白葡萄酒几乎无乙酰胆碱酯酶抑制活性,红葡萄酒对乙酰胆碱酯酶具有不同的抑制活性,抑制率最高为山葡萄酒,其抑制率为11.12%。葡萄皮渣的水、乙醇、乙酸乙酯提取物,具有抑制乙酰胆碱酯酶活性,其抑制率分别为3.91%、18.25%、20.76%,乙酸乙酯提取物的抑制效果最好。红葡萄酒和葡萄皮渣的乙酸乙酯提取物可作为辅助治疗阿尔茨海默病的先导化合物进行深入研究。     

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.     

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 .     

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.     

适宜‘法国野’葡萄的葡萄酒生产类型探究

为挖掘云南地方酿酒葡萄品种‘法国野’的酿酒潜力,筛选适合该品种的葡萄酒生产类型和基本工艺。采用4种工艺酿制2个类型葡萄酒:浸渍发酵法(maceration-fermentation,MF)酿制干红葡萄酒、冷浸渍+放血法(cold pre-fermentation maceration&saignée,CMS)酿制桃红葡萄酒、冷浸渍+放血+浸渍发酵法(cold pre-fermentation maceration,saignée and maceration-fermentation,CMS-MF)酿制干红葡萄酒,直接压榨法(direct press,DP)酿制桃红葡萄酒,其中2款干红葡萄酒均进行苹果酸-乳酸发酵(malolactic fermentation,MLF)。陈酿3个月后,对4款葡萄酒进行理化指标分析和感官评价。结果表明:与DP和MF相比,CMS和CMS-MF可分别显著提高桃红和干红葡萄酒的单宁、花色苷、总浸出物含量及色度;且CMS和DP桃红葡萄酒的香气、口感和总评得分均显著高于MF和CMS-MF干红葡萄酒,但同类型葡萄酒间的感官质量并无显著差异(P<0.05)。相关性分析表明,感官评价总评得分与酒精度和可滴定酸含量呈显著正相关,与花色苷、单宁和总浸出物含量呈显著或极显著负相关,这证明了MF和MLF工艺均不利于改善‘法国野’葡萄酒的感官质量。此外,与CMS相比,DP可显著提高葡萄汁的还原糖含量和最终葡萄酒的酒精度,并显著降低对单宁的浸提,且保持相当的感官质量。因此,酿酒葡萄‘法国野’更适合于酿造桃红葡萄酒,可将DP作为首选工艺,因其在确保葡萄酒感官质量的同时,又可减少工序、节约成本。     

Detection of ochratoxin A in tropical wine and grape juice from Brazil

BACKGROUND: Ochratoxin A (OTA) is the main mycotoxin found in grapes, wines and grape juices and is considered one of the most harmful contaminants to human health. In this study, samples of tropical wines and grape juices from different grape varieties grown in Brazil were analysed for their OTA content by high‐performance liquid chromatography. RESULTS: The detection and quantification limits for OTA were 0.01 and 0.03 µg L^?1 respectively. OTA was detected in 13 (38.24%) of the samples analysed, with concentrations ranging from < 0.03 to 0.62 µg L^?1. OTA was not detected in any of the grape juice samples. Most of the red wine samples proved to be contaminated with OTA (75%), while only one white wine sample was contaminated. However, the OTA levels detected in all samples were well below the maximum tolerable limit (2 µg L^?1) in wine and grape juice established by the European Community and Brazilian legislature. CONCLUSION: The results of this study indicate a low risk of exposure to OTA by consumption of tropical wines and grape juices from Brazil. © 2012 Society of Chemical Industry     

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。     

低温带皮浸渍发酵对薏斯琳干白葡萄酒品质的影响

采用低温带皮浸渍、澄清汁发酵的工艺酿造薏斯琳干白葡萄酒.以传统酿造工艺为对照,研究了发酵前对葡萄原料适度破碎,添加适量的果胶酶和SO2,在6℃下带皮浸渍、采用澄清汁发酵的酿造工艺(简称新工艺)对山东胶东地区的薏斯琳干白葡萄酒品质的影响.结果表明,冷浸渍48h、清汁发酵温度18℃处理条件下获得的葡萄酒香气成分更为复杂,通过分析,得知采用新工艺对品质较好的薏斯琳原料酿造的干白葡萄酒,质量优于传统酿造工艺.     

The role of processing on ochratoxin A content in Italian must and wine: a study on naturally contaminated grapes

Available data show that ochratoxin A (OTA) is a possible contaminant of wine and its concentration is higher in red wines than in white and rosé. The aim of this work was to study the fate of OTA during the main stages of the winemaking process (crushing, maceration, alcoholic fermentation, malo-lactic fermentation, bottle-aging) and the influence of technological treatments on OTA concentration in order to identify the critical process steps. Attention was focused on red winemaking, in different wineries in the south of Italy, with two naturally OTA contaminated grape varieties ('Negroamaro' and 'Primitivo') and on different vintages (2001-2002-2003). The results show that no OTA is produced during winemaking, but each operation during winemaking can modify OTA content. The OTA present in grapes to a certain degree is released to the juice during crushing. Maceration increases the OTA content, while alcoholic and malo-lactic fermentation cause a reduction in OTA in the wine.     

Stereodifferentiation of geosmin in wine

Geosmin (trans-1,10-dimethyl-trans-9-decalol), a well-known, highly odorous compound, has recently been identified and quantified in red and sweet white wines, as well as in grape juice before alcoholic fermentation. Geosmin is a chiral compound and the (-) form is much more odoriferous than the (+) form. Enantioselective multidimensional gas chromatography analysis of a purified Cabernet Sauvignon wine extract revealed the presence of only one enantiomer: (-) geosmin. In grape juices obtained from rotten grapes and in wines this compound can be found at concentrations much higher than its olfactory perception threshold, indicating that it contributes to their earthy aroma. (-) Geosmin is also the only enantiomer to have been identified in pure cultures of Streptomyces sp. and Penicillium sp. strains isolated from rotten grapes.     

Selection and modification of yeasts and lactic acid bacteria for wine fermentation

Historically, the fermentation of grape juice to wine has been carried out by indigenous yeasts found on the berry. However, in newer wine regions, e.g. the USA, inoculation with selected wine yeast strains is employed. Grape juice is high in nutritional factors and difficulties in fermentation usually arise from the inhibitory effects of the high concentration of sugar initially present and the ethanol produced. A secondary fermentation, brought about by indigenous or added lactic acid bacteria, converts malic acid to lactic acid and carbon dioxide and often occurs. This ‘malolactic’ fermentation is usually slow. For both yeast and bacterial fermentations strain selection is based more on fermentation performance than on sensory characteristics of the wine, with increased tolerance of the yeast to ethanol and of the bacteria to low pH being emphasized. Attempts to increase the malolactic fermentation rate have been made by cloning and transferring the malolactic gene from Lactobacillus to wine yeast. In early attempts to produce wines with enhanced or novel sensory characteristics a leucine-less mutant of a homothallic wine yeast has been obtained which does not produce isoamyl alcohol.     

Protein removal from a Chardonnay juice by addition of carrageenan and pectin

Backgrounds and Aims: Bentonite is commonly added to white wines to remove the grape proteins responsible for haze formation. Despite being effective, this technique has drawbacks; thus, new solutions are desirable. The ability of carrageenan and pectin to remove heat‐unstable grape proteins, and the impact that such addition has on the physicochemical and sensorial profile of a wine were assessed. Methods and Results: Carrageenan and pectin were added separately or in combination to a Chardonnay juice prior to fermentation. Both adsorbents removed proteins (up to 75%), thus increasing wine protein stability. Carrageenan was more effective than pectin at increasing wine protein stability. Conclusions: Pectin and carrageenan removed protein and partially stabilized the samples of the wine. Significance of the Study: Pre‐fermentation addition of pectin or carrageenan may provide the wine industry with an alternative protein stabilization procedure.     

香蕉菠萝复合果酒双酵母发酵工艺的研究

以新鲜香蕉、菠萝汁为原料,利用葡萄酵母、安琪酵母、水蜜桃酵母、白梨酵母为发酵菌株,从发酵过程中的酒精含量、残糖含量、酵母量的情况选出最优菌株组合进行双酵母组合发酵实验,研究初始糖度、发酵温度、初始pH值、亚硫酸氢钠浓度对发酵的影响。结果表明白梨酵母(a)和安琪活性高酵母(b)以1∶3的比例发酵复合果酒质量较好,初始糖度为28%,亚硫酸氢钠为0.01%,发酵温度为12℃,pH值3.6。