可同化氮对葡萄酒发酵香气物质积累及代谢调控的影响

葡萄汁中酵母可同化氮的含量和组成,不仅影响酵母生长和酒精发酵,还对葡萄酒中高级醇、支链酸、酯类等发酵香气物质的积累起决定性影响。支链氨基酸、芳香族氨基酸等由酿酒酵母通过Ehrlich路径代谢生成相应的高级醇及酸,高级醇和酸与糖代谢及脂肪酸代谢产物结合生成酯类,构成发酵香气的主要成分。合理的葡萄汁氮源组成和外源添加氮源对葡萄酒发酵过程中优良香气物质的积累,减少不良香气物质,提高酒的感官品质有重要意义。本文总结了酵母可同化氮量与发酵香气积累相关的研究成果,综述酿酒酵母氮代谢产生香气物质的路径及其基因表达调控的研究进展。     

可同化氮含量对赤霞珠葡萄酒发酵和香气成分的影响

选取山西戎子酒庄有限公司不同位置的三个葡萄园(驮腰坡,东廒北,东廒南),对各葡萄园进行土壤含氮量、赤霞珠葡萄及葡萄酒发酵过程中可同化氮(YAN)含量、葡萄酒理化指标与香气成分的检测分析。结果表明,葡萄果实可同化氮含量可能主要与土壤铵态氮含量有关。不同葡萄园的赤霞珠葡萄汁可同化氮的含量不同,均超过了150 mg/L,能保证发酵顺利进行。如果需要添加可同化氮时,应以此时测定的可同化氮含量为依据,避免添加过量。原酒中酯类和醇类相对含量由高到低依次为：驮腰坡＞东廒南助剂＞东廒北＞东廒南,这与葡萄汁中可同化氮含量呈正相关。     

模拟葡萄汁中可同化氮和还原糖对酵母发酵特性的影响

为研究葡萄汁中可同化氮和还原糖对酵母发酵特性的影响,设计150、240、330、420、500?mg/L可同化氮质量浓度和170、200、230?g/L还原糖质量浓度,共计15?个处理,测定了模拟葡萄汁酒精发酵过程中酵母生长、还原糖消耗和可同化氮消耗的变化。结果表明,模拟汁中可同化氮质量浓度过低（150?mg/L）则不能充分满足酵母生长的需要,同时限制了酵母的还原糖消耗速率,通过提高初始还原糖质量浓度至200?g/L可促进酒精发酵进行;酵母在初始可同化氮质量浓度高于240?mg/L的模拟汁中可以正常生长,此时初始还原糖、可同化氮质量浓度对酵母生长量均无显著影响,还原糖含量最直接影响酿酒酵母菌株的发酵特性,决定发酵时间长短,表现为在初始还原糖质量浓度较低（170?g/L）的模拟汁中,酵母生长速率随着模拟汁初始可同化氮质量浓度的升高而加快,在初始还原糖质量浓度较高（200～230?g/L）的模拟汁中,酵母生长速率不受初始可同化氮质量浓度的影响;当模拟汁初始可同化氮质量浓度高于330?mg/L时,酵母对可同化氮的消耗开始出现剩余,剩余量随着模拟汁初始可同化氮质量浓度的升高而增加,此时可同化氮质量浓度能够充分满足酵母可同化氮代谢的需要,且酵母对可同化氮消耗量随着初始还原糖质量浓度的增加而略有减少。     

低温耗氮技术在低醇白葡萄酒酿造中的应用

采用低温耗氮方式进行了低醇葡萄酒的发酵工艺研究。在发酵过程中摸索了不同的拉低温时机、低温温度及去除部分生物量等对于低醇葡萄酒发酵中的酵母生长代谢、总氮量、α-氨基氮、还原糖、总酸等理化、感官指标以及稳定性的影响,进而评价低温耗氮技术酿造较高稳定性的低醇葡萄酒的可能性。结果表明,发酵前期拉低温处理和去除部分生物量能够明显增加酵母菌的耗氮,改变其生长代谢状况。在发酵36 h时拉低温至0℃处理,之后低温离心并回填1/5酵母生物量至醪液继续正常发酵的低醇葡萄酒,酒精度更易控制在低醇范围,微生物稳定性更好,且葡萄酒具有更好的品种特性。     

氮源对葡萄酒中挥发性化合物含量的影响研究

选取云南省德钦县阿东、红坡、东水和布村4个村庄葡萄园的赤霞珠葡萄,测定葡萄汁中氨基酸和酵母可同化氮含量,并对所酿葡萄酒中挥发性化合物含量进行测定,分析葡萄汁中酵母可同化氮含量与葡萄酒中挥发性化合物含量之间的关系。结果表明,葡萄酒中异丁醇与葡萄汁中缬氨酸含量相关,葡萄酒中乙酸己酯和乙酸乙酯与葡萄酒中丝氨酸含量相关,葡萄酒中总酯与葡萄汁中总氨基酸含量相关;葡萄酒中正己醇和苯甲醇、乙酸苯乙酯、己酸和辛酸与葡萄汁中的酵母可同化氮含量呈正相关,而异丁醇和丁二酸二乙酯与葡萄汁中的酵母可同化氮含量呈负相关。     

葡萄酒酿造过程中双乙酰的形成因素分析

适量的双乙酰会增加葡萄酒风味的复杂性,葡萄酒中的双乙酰主要是在苹果酸- 乳酸发酵过程中形成的。本文综述了葡萄酒酿造过程中双乙酰的形成影响因素,包括葡萄酒成分、乳酸菌种、苹果酸- 乳酸发酵的条件及陈酿方式等,以期对控制葡萄酒中双乙酰的含量,改善葡萄酒的风味提供参考。     

葡萄酒发酵过程中氮源的控制与管理

氮源在葡萄酒发酵的过程中起着重要的作用,对氮源的控制与管理是葡萄酒发酵过程中不可缺少的环节,也是最重要的环节。因此在葡萄酒发酵的过程中,要加强对氮源的控制与管理。文章主要对发酵过程中葡萄汁中氮的组成和存在形式做介绍以及对影响葡萄汁含氮量的因素的概述,进而强调氮含量对酵母的影响与酵母发酵助剂的使用,希望为葡萄酒产业提供借鉴。     

不同种类可同化氮对蓝莓果酒酒精发酵的影响

采用蓝莓为原料,向初始发酵液中添加不同种类、不同浓度可同化氮进行果酒发酵,发酵结束后低温陈酿1个月,测定果酒酵母数量、pH值、残糖含量、酒精度、醇类与酯类含量。研究结果显示:随初始发酵液中可同化氮浓度增加,果酒中酵母总数增高、生长速率加快、果酒残糖含量降低、酒精度增加,酒精发酵效率增加;随初始发酵液中游离氨基酸浓度增加,醇类、酯类含量均增加;随初始发酵液中磷酸氢二胺浓度增加,醇类含量先升高后降低,酯类含量不断增加。     

发酵营养剂NutrienFast添加时期对葡萄酒发酵的影响

在含糖量高、酵母可同化氮不足的葡萄汁中,研究不同发酵时期添加安琪发酵营养剂NutrienFast对葡萄酒发酵的影响。结果表明,在发酵第3天（糖消耗36.26%）、第4天（糖消耗到达44.18%）时添加发酵营养剂NutrienFast对葡萄酒发酵的影响最大,此时CO2累积质量损失最高,分别为129.62 g/L和128.82 g/L;葡萄汁中的酵母干物质含量达到最高值,分别为3.57 g/L、3.62 g/L;葡萄酒相对密度、残糖含量最低;酒精度最高,分别为16.5%vol、16.4%vol,酒精发酵完全（残糖＜4 g/L）,可有效解决或者预防葡萄酒的发酵停止或停滞问题。     

葡萄酒中氨基甲酸乙酯的变化规律及控制研究

本文采用SPE结合GC-MS法对我国烟台、沙城、昌黎、新疆新酿原酒中的氨基甲酸乙酯的含量进行了检测,并对可能导致葡萄酒中氨基甲酸乙酯含量升高的生产过程进行试验分析。结果发现,不同产区氨基甲酸乙酯的含量在2.17~13.05μg/L。其原料土壤中的氮元素含量、葡萄酒的储存时间、储存温度,影响着葡萄酒中氨基甲酸乙酯含量;发酵过程发酵助剂的使用对氨基甲酸乙酯的影响取决与原料的可吸收氮含量。文章中的数据分析对葡萄酒中氨基甲酸乙酯的国标制定提供支撑,创新的分析了发酵过程中发酵助剂的使用对葡萄酒氨基甲酸乙酯的影响,为国内葡萄酒生产企业起到指导性意义。     

添加酵母可同化氮对桑葚酒功能成分及抗氧化活性的影响

通过在桑葚酒发酵过程中添加酵母可同化氮,探究桑葚酒发酵过程中总黄酮、总酚、花色苷、1-脱氧野尻霉素（DNJ）含量及抗氧化性能变化。结果表明,添加质量浓度为240 mg N/L的酵母可同化氮,可在发酵前期加快总黄酮、总酚、DNJ功能成分溶出。当发酵时间为3 d、3 d、6 d时,其含量最高,分别为3 432.57 mg/L、965.48 mg/L、121.27 mg/L。当发酵时间为3 d时,1,1-二苯基-2-三硝基苯肼（DPPH）、2,2-联氮-二（3-乙基-苯并噻唑-6-磺酸）二铵盐（ABTS）自由基清除能力、铁离子还原能力最高,分别为1 459.46 mg/L、3 400.43 mg/L、3 323.00 mg/L。表明添加酵母可同化氮可以提高桑葚酒功能成分含量及抗氧化活性。     

Growth of non-Saccharomyces yeasts affects nutrient availability for Saccharomyces cerevisiae during wine fermentation

Yeast produces numerous secondary metabolites during fermentation that impact final wine quality. Although it is widely recognized that growth of diverse non-Saccharomyces (NS) yeast can positively affect flavor complexity during Saccharomyces cerevisiae wine fermentation, the inability to control spontaneous or co-fermentation processes by NS yeast has restricted their use in winemaking. We selected two NS yeasts from our Uruguayan native collection to study NS-S. cerevisiae interactions during wine fermentation. The selected strains of Hanseniaspora vineae and Metschnikowia pulcherrima had different yeast assimilable nitrogen consumption profiles and had different effects on S. cerevisiae fermentation and growth kinetics. Studies in which we varied inoculum size and using either simultaneous or sequential inoculation of NS yeast and S. cerevisiae suggested that competition for nutrients had a significant effect on fermentation kinetics. Sluggish fermentations were more pronounced when S. cerevisiae was inoculated 24h after the initial stage of fermentation with a NS strain compared to co-inoculation. Monitoring strain populations using differential WL nutrient agar medium and fermentation kinetics of mixed cultures allowed for a better understanding of strain interactions and nutrient addition effects. Limitation of nutrient availability for S. cerevisiae was shown to result in stuck fermentations as well as to reduce sensory desirability of the resulting wine. Addition of diammonium phosphate (DAP) and a vitamin mix to a defined medium allowed for a comparison of nutrient competition between strains. Addition of DAP and the vitamin mix was most effective in preventing stuck fermentations.     

不同种类可同化氮素对黄酒酵母产高级醇能力的影响

为研究不同种类可同化氮素对黄酒酵母产高级醇的影响,通过添加不同种类可同化氮素进行2株黄酒酵母的发酵实验,使用GC-MS对发酵液中高级醇进行测定,比较发酵结束时高级醇含量变化。结果表明:RWBL Y1739 LZH异戊醇合成能力较强,RWBL Y1615 ZC β-苯乙醇合成能力较强;可同化氮素的添加对酵母生长、乙醇产生有着重要影响;对于酵母RWBL Y1739 LZH和RWBL Y1615 ZC,无机氮素降低高级醇的效果最好(29.97%~63.15%),氯化铵降低高级醇的幅度最大(62.60%,63.15%),添加特定的氨基酸能加强酵母Ehrlich途径,产生更多高级醇。     

Implications of nitrogen nutrition for grapes, fermentation and wine

This review discusses the impacts of nitrogen addition in the vineyard and winery, and establishes the effects that nitrogen has on grape berry and wine composition and the sensory attributes of wine. Nitrogen is the most abundant soil‐derived macronutrient in a grapevine, and plays a major role in many of the biological functions and processes of both grapevine and fermentative microorganisms. Manipulation of grapevine nitrogen nutrition has the potential to influence quality components in the grape and, ultimately, the wine. In addition, fermentation kinetics and formation of flavour‐active metabolites are also affected by the nitrogen status of the must, which can be further manipulated by addition of nitrogen in the winery. The only consistent effect of nitrogen application in the vineyard on grape berry quality components is an increase in the concentration of the major nitrogenous compounds, such as total nitrogen, total amino acids, arginine, proline and ammonium, and consequently yeast‐assimilable nitrogen (YAN). Both the form and amount of YAN have significant implications for wine quality. Low must YAN leads to low yeast populations and poor fermentation vigour, increased risk of sluggish/stuck/slow fermentations, increased production of undesirable thiols (e.g. hydrogen sulfide) and higher alcohols, and low production of esters and long chain volatile fatty acids. High must YAN leads to increased biomass and higher maximum heat output due to greater fermentation vigour, and increased formation of ethyl acetate, acetic acid and volatile acidity. Increased concentrations of haze‐causing proteins, urea and ethyl carbamate and biogenic amines are also associated with high YAN musts. The risk of microbial instability, potential taint from Botrytis‐infected fruit and possibly atypical ageing character is also increased. Intermediate must YAN favours the best balance between desirable and undesirable chemical and sensory wine attributes. ‘Macro tuning’, of berry nitrogen status can be achieved in the vineyard, given genetic constraints, but the final ‘micro tuning’ can be more readily achieved in the winery by the use of nitrogen supplements, such as diammonium phosphate (DAP) and the choice of fermentation conditions. This point highlights the need to monitor nitrogen not only in the vineyard but also in the must immediately before fermentation, so that appropriate additions can be made when required. Overall, optimisation of vineyard and fermentation nitrogen can contribute to quality factors in wine and hence affect its value. However, a better understanding of the effect of nitrogen on grape secondary metabolites and different types of nitrogen sources on yeast flavour metabolism and wine sensory properties is still required.     

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。     

酵母可同化氮含量对低产硫化氢酿酒酵母发酵特性的影响

该研究以3株本土低产硫化氢酿酒酵母（Saccharomyces cerevisiae）41y5、182y12和174y1为研究对象,研究酵母可同化氮（YAN）的质量浓度对其发酵特性的影响,并对不同菌株各指标间的相关性进行分析。结果表明,随着初始YAN质量浓度的升高,酵母的生物量越大,发酵周期越短;发酵后模拟酒的挥发酸含量和pH值升高;初始YAN质量浓度对菌株产H2S的影响不同。初始YAN质量浓度与CO2平均释放速率、挥发酸含量、pH值呈极显著正相关（P＜0.01）,与最大生物量呈显著正相关（P＜0.05）,与H2S释放量无显著相关性（P＞0.05）,且在发酵过程中H2S的释放量与发酵后模拟酒的pH值存在显著的正相关（P＜0.05）。与酿酒酵母41y5和182y12相比,酿酒酵母174y1在4个初始YAN质量浓度下,生物量均最高,发酵周期均最短,发酵性能优良。     

Effects of temperature, ammonium and glucose concentrations on yeast growth in a model wine system

In enology, alcoholic fermentation is a complex process involving several mechanisms. Slow and incomplete alcoholic fermentation is a chronic problem for the wine industry and factors leading to sluggish and stuck fermentations have been extensively studied and reviewed. The most studied cause of sluggish and stuck fermentation is the nitrogen content limitation. Nevertheless, other factors, such as temperature of fermentation and sugar concentration can affect the growth of yeasts. In this study we modelled the yeast growth‐cycle in wine model system as a function of temperature, sugar and ammonium concentrations; the individual effects and the interaction of these factors were analysed by means of a quadratic response surface methodology. Cell concentrations and weight loss were monitored in the whole wine fermentation process. The results of central composite design show that lower is the availability of nitrogen, higher is the cell growth rate; moreover, initial nitrogen concentration also influences survival time of Saccharomyces cerevisiae.