葡萄酒酵母不同菌种发酵特性研究

以17株生产上常用的葡萄酒酵母为试验菌种,进行了葡萄酒酵母发酵特性的研究．试验结果表明,8、12、19、号菌种适合于干白葡萄酒的发酵．用这些苗种发酵干白葡萄酒发酵平稳彻底,发酵时间短,产酒率高,残糖和挥发酸含量低．干浸出物的消耗较少,同时还能防止发酵中止,降低葡萄酒的生产成本。酿制的酒风味好,质量高。而5、15号菌种有降酸的作用,用于含酸量较高的葡萄汁发酵,可以取得较满意的结果。     

葡萄酒活性干酵母的使用方法

随着葡萄酒酿造技术的进步,接种人工酵母进行发酵的工艺得到越来越广泛的应用。优良的葡萄酒酵母是保证发酵正常、提高葡萄酒质量的一个重要因素。特别是许多新工艺在葡萄酒生产中的推广,如热浸提法生产红葡萄酒和葡萄汁前处理低温发酵生产干白葡萄酒,葡萄汁中原有的酵母大部分被杀死或除去,必须接种人工酵母进行发酵。活性干酵母使用方便,不受接种时间限制,应用日趋广泛。掌握正确的使用方法可以充     

生产葡萄酒的新方法

葡萄酒的生产特点,是当葡萄汁发酵后,在其液体表面上形成一层称为葡萄酒酵母皮膜的产膜酵母,所形成的这种皮膜能赋与葡萄酒以特有的香味。葡萄酒的产膜酵母,可     

不同酵母菌对白兰地挥发性成分的影响

研究不同酵母菌株对白兰地挥发性成分形成的影响,用3种商品化的葡萄酒酵母发酵白玉霓葡萄汁,用气质联用方法测定了葡萄汁发酵前后以及葡萄酒蒸馏前后成分的差异,检测到35种挥发性成分中主要的成分是5种醇类、5种酯类和5种酸类.高级醇中异戊醇的产生量较高,甲醇生成量相近,但产酒精的能力不同,酯类成分的种类和数量差别较大.不同酵母菌种类会影响白兰地的挥发性风味成分.     

玫瑰香干红葡萄酒自然发酵过程中优势酵母分离鉴定及其应用潜力分析

为酿造特色玫瑰香干红葡萄酒,开发本土发酵剂是目前重要发展方向。从昌黎产区玫瑰香干红葡萄酒自然发酵醪中共分离得到337株酵母,通过WL(Wallerstein laboratory)鉴别培养基对其进行分类鉴定、计数,将其鉴别为7大类,根据计数结果选取优势酵母接种至BIGGY(bismuth sulphite glucose glycine yeast)固体培养基,从中进一步筛选不产H2S酵母,进行分子鉴定,结果显示HBKS-Y1、HBKS-Y3为酿酒酵母,HBKS-Y2为葡萄汁有孢汉逊酵母。考察3株本土酵母酿造因子耐性,发现3株酵母对乙醇、SO2、糖度均具有较高耐性,满足葡萄酒酿造要求;以商用活性干酵母FX10葡萄汁发酵为对照,考察3株酵母对玫瑰香葡萄汁单菌、混菌发酵理化指标和香气成分的影响,3株本土酵母单菌和混菌发酵各指标(例如:还原糖、酒精度、总酸、挥发酸、甘油和乙醛含量)均符合干红葡萄酒酿造标准。同时发现,与HBKS-Y2单菌发酵相比,3株酵母混菌发酵总酸和挥发酸含量降低,对葡萄酒有益,且混菌发酵对葡萄酒其他理化指标没有不利影响。本土酵母发酵尤其是混菌发酵,表征玫瑰香品种香气的萜烯醇类物质含量明显高于活性干酵母发酵。以上结果表明,3株本土酵母可以应用于玫瑰香干红葡萄酒的酿造,且3株酵母混菌发酵对突出玫瑰香干红葡萄酒品种香气具有一定的应用潜力。     

不同有机氮源对葡萄酒发酵的影响

分别使用酵母浸粉和混合氨基酸作为模拟葡萄汁（36 °Bx）的有机氮源发酵葡萄酒,以保证葡萄酒的正常发酵和最终产品品 质。 通过测定发酵过程中的二氧化碳生成量、还原糖、可同化氮、甘油和挥发性化合物含量变化,比较酵母浸粉和混合氨基酸对葡萄酒 品质的影响。 结果表明,使用酵母浸粉耗还原糖量为295.7 g/L,生成乙醇97.20 g/L、甘油26.50 g/L、乙酸1.08 g/L和乙酸乙酯46.05 mg/L, 与使用混合氨基酸相比,多消耗还原糖130.47 g/L,多生成乙醇46.14 g/L、甘油7.95 g/L和乙酸0.54 g/L,增幅分别为78.95%、90.38%、 42.84%和99.35%。 使用酵母浸粉比混合氨基酸的发酵程度大,速度快。 因此,可用适量酵母浸粉替代混合氨基酸作为葡萄酒发酵的 氮源补充。     

干白葡萄酒工艺研究进展

干白葡萄酒是用白葡萄汁经过酒精发酵后获得的酒精饮料,在发酵过程中不存在葡萄汁对葡萄固体部分的浸渍现象。此外,干白葡萄酒的质量,主要决定源于葡萄品种的一类香气和源于酒精发酵的二类香气以及酚类物质的含量。所以,在葡萄品种一定的条件下,葡萄汁取汁速度及其质量、影响二类香气形成的因素和葡萄汁以葡萄酒的氧化现象即成为影响干白葡萄酒质量的重要工艺条件,这也是近年来各国干白葡萄酒工艺研究     

葡萄酒氧化与二氧化碳含量关系探讨

葡萄酒中所含有的成分是十分复杂的,尤其是当葡萄酒装瓶后,由于密封不良,或其它原因,使葡萄酒与空气中的氧接触,产生葡萄酒的氧化现象,造成葡萄酒的颜色变深,果香味变异,酒液混浊,产生沉淀等现象。所以防止葡萄酒的氧化,对提高葡萄酒的稳定性有重大意义。对葡萄酒来讲,除在发酵时,由于葡萄汁中含有的葡萄糖需转化为酒精及酵母的生长,都需要消耗大量的氧气外,而在发酵结束后,葡萄酒最好是与氧气隔绝,以免造成葡萄酒与空气中氧的接触,而使葡萄酒被氧     

混菌发酵对贺兰山东麓‘赤霞珠’干红葡萄酒香气的影响

为研究非酿酒酵母与酿酒酵母混合发酵对贺兰山东麓‘赤霞珠’葡萄酒香气品质的影响,确定最适的混菌发酵接种工艺,以单一酿酒酵母发酵作为对照,选用葡萄汁有孢汉逊酵母（Hanseniaspora uvarum）Yun268、发酵毕赤酵母（Pichia fermentans）Z9Y-3和毕赤克鲁维酵母（Pichia kluyveri）C735三种优选非酿酒酵母,分别与酿酒酵母进行不同比例接种（10∶1、1∶1）及不同时间接种（提前48 h顺序接种、同时接种）的发酵方案酿造‘赤霞珠’干红葡萄酒,评价酒样理化及香气指标。结果表明：与对照相比,所有混菌发酵处理均提高了0.38～1.11 g/L葡萄酒甘油产量,同时降低了0.33%～1.9%乙醇体积分数。发酵毕赤酵母Z9Y-3与酿酒酵母按10∶1比例同时接种,在确保乙醇发酵顺利完成的同时,还能够显著增加干浸出物含量23.6%,增加甘油含量4.6%,此外在香气方面能够最大程度发挥其产香特性,显著增加芳樟醇、β-大马士酮、辛酸乙酯、乙酸苯乙酯、癸酸甲酯和辛酸异戊酯等30种香气物质的含量,使挥发性成分总量提升45%,并在感官上增强了葡萄酒的浆果香、热带水果香、花...     

橡木桶与葡萄酒成熟

62葡萄酒是新鲜葡萄或葡萄汁发酵获得的饮料，其主要成分为醇类、酸类、酚类化合物，这些成分赋予了葡萄酒的口感和独特的风格。葡萄发酵结束后的原酒，酒体粗糙，酸涩，饮用质量较差，需经过一定的贮藏期进行氧化还原、酯化、缩合、聚合作用来达到最佳饮用质量，这一质量变化过程就是葡萄酒的陈酿。葡萄酒的成熟过程中，适度氧化是必须的，适量的氧使单宁和色素缓慢氧化，使葡萄酒颜色由鲜红色逐渐变为宝石红色，同时葡萄酒的苦涩味和粗糙感逐渐减少、消失。用橡木桶陈酿葡萄酒就能满足这一要求。橡木桶具有通透性，能够给陈酿的葡萄酒提供…     

美极梅奇酵母的代谢特性及其在葡萄酒生产中的应用前景

美极梅奇酵母是一种在成熟葡萄浆果表面和葡萄酒发酵初级阶段普遍存在的非酵母属酵母。该文从该酵母与葡萄酒相关环境的适应性、产酶特性、抗菌特性,及其对酒精发酵、葡萄酒成分、风味品质与色泽稳定性等方面的影响进行了论述,以期为美极梅奇酵母在葡萄酒生产中的合理应用提供参考。美极梅奇酵母在降低葡萄酒酒精含量、增加甘油含量、增强品种香气、提高感官品质、促进红葡萄酒色泽稳定等方面具有良好的潜质,但这些特性也存在着较大的菌株差异性。     

国产葡萄酒中甘油含量的调查与分析

目的通过对我国8个主要产区的89支品牌葡萄酒和4支疑似劣质葡萄酒中甘油含量的调查和分析,为国产葡萄酒的初步品质鉴别提供重要参考。方法采用甘油激酶法对葡萄酒中的甘油含量进行检测,采用葡萄酒、果酒通用分析方法 GB 15038—2006中的蒸馏法测定葡萄酒中的酒精度含量,对甘油含量及计算得到甘油与酒精度的比值(简称甘酒比)进行初步比较分析。结果葡萄酒中甘油的含量与气候、葡萄品种与成熟度等因素有关,正常发酵的葡萄酒甘油的含量为4~10 g/L,甘酒比应处于6%~10%。绝大部分品牌葡萄酒的相关指标在正常范围之内,指标出现异常则需要采用其他分析手段做进一步测试。结论葡萄酒中甘油含量和甘酒比可为葡萄酒的初步品质鉴别提供重要依据,建议加强对葡萄酒中甘油含量的检测和监管。     

Inhibition of malolactic fermentation by Saccharomyces during alcoholic fermentation under low- and high-nitrogen conditions: a study in synthetic media

The ability of different wine yeast ( Saccharomyces cerevisiae ) to inhibit malolactic bacteria ( Oenococcus oeni ) and the influence of nitrogen were studied using a synthetic grape juice. Malolactic fermentation was induced in fermenting synthetic grape juice or synthetic wines inoculated with different commercial strains of S. cerevisiae. O. oeni was generally inhibited in wines that contained higher concentrations of total SO₂ although many yeast strains only inhibited the bacteria during fermentation under high nitrogen conditions. Yeast produced higher amounts of SO₂ during fermentation under high nitrogen conditions suggesting that nitrogen affected the malolactic fermentation by influencing yeast SO₂ production. However, the production of SO₂ by yeast did not always account for the inhibition of O. oeni , suggesting the presence of other inhibitory mechanisms.     

Effects of nutrient supplementation on fermentation kinetics, H2S evolution, and aroma profile in Verdicchio DOC wine production

Different yeast nutrient additions were studied for the 2008 and 2009 vintages of Verdicchio grape juice fermentation. Addition of yeast derivatives at the beginning of fermentation and/or different amounts of diammonium phosphate at various times within the first half of fermentation were examined, with initial yeast assimilable nitrogen concentrations set at 200 and 250 mg l^?1. Supplementation with glutathione in combination with this nitrogen addition was also evaluated. Fermentation rates were monitored throughout these fermentations carried out under different nutrient conditions. H₂S production during fermentation and synthesis of volatile compounds in the finished wines were quantified; the wines also underwent sensory evaluation. The fermentation kinetics were almost exclusively influenced by the inorganic nitrogen supplementation with diammonium phosphate. H₂S evolution was more affected by assimilable nitrogen than glutathione. Diammonium phosphate significantly reduced H₂S production, with a further reduction in the presence of yeast derivative. This nitrogen supplementation yielded higher concentrations of acetate esters, and in particular of isoamyl acetate (fruity aromas), which positively influences the analytical and aroma profile of wines and results in a general reduction in 2-phenylethanol production (floral aromas). Overall results (two harvesting times and vintages) indicate that the management with diammonium phosphate and yeast derivative supplementation improves the kinetics of fermentation and provides a good tool to reduce H₂S formation and increase the analytical and sensory quality of Verdicchio wine.     

Influence of fermentation temperature on volatile thiols concentrations in Sauvignon blanc wines

The effect of Saccharomyces cerevisiae strains on the amount of 4-mercapto-4-methylpentan-2-one, a major varietal aroma of Sauvignon blanc wines, was demonstrated by previous research work. However, the influence of different alcoholic fermentation parameters on the levels of volatile thiols (4-mercapto-4-methylpentan-2-one, 3-mercaptohexan-1-ol and 3-mercaptohexyl acetate) in wines has not yet been investigated. The impact of fermentation temperature on the final amount of volatiles thiols and on some other analytical parameters (ethanol, total acidity, residual sugars, volatile acidity) was determined in a model medium and in grape juice. Interaction between fermentation temperature and yeast strain was also tested. The fermentation temperature influenced the amount of volatile thiols irrespective of the yeast strain used. The final levels of 4MMP and 3MH in model medium and in wines were higher when the alcoholic fermentation is conducted at 20 degrees C than at 13 degrees C. The 3MHA, which was correlated with the amount of 3MH determined in wines, was also higher when the alcoholic fermentation was conducted at 20 degrees C. From a technological point of view, the choice of yeast strain and fermentation temperature has a decisive influence on the concentrations of the varietal aromas of Sauvignon blanc wines.     

Production of white wine by Saccharomyces cerevisiae immobilized on grape pomace

White wine was produced with Saccharomyces cerevisiae cells immobilized on grape pomace, by natural adsorption. The support, the main solid waste from the wine industry, consisted of the skins, seeds and stems. Immobilization was tested using different media, namely complex culture medium, raw grape must and diluted grape must. Grape pomace was revealed to be an appropriate support for yeast cell immobilization. Moreover, grape must was shown to be the most suitable medium as immobilized cells became adapted to the conditions in the subsequent alcoholic fermentation in the wine‐making process. The wines produced, either with immobilized cells or with free cells, were subjected to chemical analysis by HPLC (ethanol, glycerol, sugars and organic acids) and by gas chromatography (major and minor volatile compounds); additionally, colour (CIELab) and sensory analysis were performed. The use of immobilized systems to conduct alcoholic fermentation in white wine production proved to be a more rapid and a more efficient process, especially when large amounts of SO₂ were present in the must. Furthermore, the final wines obtained with immobilized cells demonstrated improved sensory properties related to the larger amounts of ethanol and volatile compounds produced. The more intense colour of these wines could be a drawback, which could be hindered by the reutilization of the biocatalyst in successive fermentations. Copyright © 2012 The Institute of Brewing & Distilling     

Discovering a chemical basis for differentiating wines made by fermentation with 'wild' indigenous and inoculated yeasts: role of yeast volatile compounds

Background and Aims:  Winemakers are constantly searching for new techniques to modulate wine style. Exploiting indigenous yeasts present in grape must is re-emerging as a commercial option in New World wine regions. Wines made with indigenous or 'wild' yeasts are perceived to be more complex by showing a greater diversity of flavours; however, the chemical basis for the flavour characteristics is not yet defined. In order to evaluate techniques for making wine with the 'wild yeast fermentation' character more reliably, it is necessary to define the salient chemical characteristics of such wines.
Methods and Results:  Pairs of Chardonnay wines were prepared from the same must and subjected to similar fermentation conditions in the wineries of origin, except for the mode of inoculation. Reference wines were made by inoculation with a Saccharomyces cerevisiae starter culture, whereas companion wines were allowed to undergo fermentation with the indigenous microflora. Of all wine chemicals analysed, only yeast-derived volatile fermentation products showed significant differences between the yeast treatments.
Conclusions:  Inoculated wines were associated with the esters ethyl hexanoate and 3-methylbutyl acetate and formed a clear cluster by principal component analysis. By comparison with inoculated wines, 'wild' yeast fermented wines showed high variability in volatile compounds that contribute to wine aroma, with higher concentrations of 2-methylpropanol, 2-methylbutanoic acid, ethyl 2-methylpropanoate, ethyl decanoate and ethyl dodecanoate potentially being sensorially important.
Significance of the Study:  This study shows that yeast-derived volatile fermentation products are a key difference between inoculated and uninoculated ferments and provides a chemical basis for the 'wild yeast fermentation' character.     

Evaluating the Influence of Malolactic Fermentation Inoculation Practices and Ageing on Lees on Biogenic Amine Production in Wine

Biogenic amines are compounds, produced primarily by lactic acid bacteria (LAB) that negatively affect the wholesomeness of wine. Standard winemaking practices can greatly influence the levels of biogenic amines in wine. The aim of this study was to determine the relative contribution of different malolactic fermentation (MLF) practices and ageing of wines on fermentation lees to the final levels of biogenic amines. Wines were made on small scale over two harvest seasons with two red grape cultivars. Treatments included spontaneous MLF, co-inoculated MLF, MLF inoculated after alcoholic fermentation (conventional inoculation) and 4 months of ageing in the presence and absence of fermentation lees of all MLF treatments. Biogenic amine concentrations were measured by high-performance liquid chromatography at key winemaking stages and statistically analysed for the effects of MLF treatment and winemaking stage. Results indicate that the presence of indigenous LAB increased the risk of biogenic amine formation. Inoculation proved to reduce biogenic amine production over time compared to spontaneous MLF and co-inoculation even more than conventional inoculation. The presence of yeast lees during ageing generally led to higher final concentrations of biogenic amines in wines than the absence of lees. This study confirms other works that conclude that spontaneous MLF and uncontrolled ageing on yeast lees are generally unpredictable and pose a risk of biogenic amine contamination in finished wines.     

Sweet Wine Production by Two Osmotolerant Saccharomyces cerevisiae Strains

The use of Saccharomyces cerevisiae to produce sweet wine is difficult because yeast is affected by a hyperosmotic stress due to the high sugar concentrations in the fermenting must. One possible alternative could be the coimmobilization of the osmotolerant yeast strains S. cerevisiae X4 and X5 on Penicillium chrysogenum strain H3 (GRAS) for the partial fermentation of raisin musts. This immobilized has been, namely, as yeast biocapsules. Traditional sweet wine (that is, without fermentation of the must) and must partially fermented by free yeast cells were also used for comparison. Partially fermented sweet wines showed higher concentration of the volatile compounds than traditionally produced wines. The wines obtained by immobilized yeast cells reached minor concentrations of major alcohols than wines by free cells. The consumption of specific nitrogen compounds was dependent on yeast strain and the cellular immobilization. A principal component analysis shows that the compounds related to the response to osmotic stress (glycerol, acetaldehyde, acetoin, and butanediol) clearly differentiate the wines obtained with free yeasts but not the wines obtained with immobilized yeasts.     

Volatile compounds formation in alcoholic fermentation from grapes collected at 2 maturation stages: influence of nitrogen compounds and grape variety

The aim of this work was to study the influence of nitrogen compounds on the formation of volatile compounds during the alcoholic fermentation carried out with 4 nonaromatic grape varieties collected at 2 different maturation stages. To do this, Monastrell, Merlot, Syrah, and Petit Verdot grapes were collected 1 wk before harvest and at harvest. Then, the musts were inoculated with the same Saccharomyces cerevisiae yeast strain and were fermented in the same winemaking conditions. Amino acids that showed the highest and the lowest concentration in the must were the same, regardless of the grape variety and maturation stage. Moreover, the consumption of amino acids during the fermentation increased with their concentration in the must. The formation of volatile compounds was not nitrogen composition dependent. However, the concentration of amino acids in the must from grapes collected 1 wk before harvest can be used as a parameter to estimate the concentration of esters in wines from grapes collected at harvest and therefore to have more information to know the grape oenological capacity. Application of principal components analysis (PCA) confirmed the possibility to estimate the concentration of esters in the wines with the concentration of nitrogen compounds in the must.