微生物对葡萄酒香气的影响综述

香气是葡萄酒的重要感官质量指标之一,葡萄酒的酿造过程其本质是酵母菌、乳酸菌等微生物代谢活动的过程,使葡萄酒产品的香气表现得复杂和多样性.综述了酿酒酵母、非酿酒酵母、乳酸菌及霉菌在葡萄酒酿造过程中的作用,分析了酿酒微生物糖苷酶在酿酒过程中促进葡萄酒香气糖苷水解释放的研究进展.最后,就酿酒微生物应用于葡萄酒酿造,改善葡萄酒风味特征的研究重点和研究手段作了展望.     

葡萄酒苹果酸乳酸发酵研究进展

苹果酸乳酸发酵(Malolactic fermentation,MLF)指在乳酸菌作用下将L-苹果酸脱羧基形成L-乳酸的过程,是葡萄酒生产难以控制的二次发酵过程,主要由酒类酒球菌引起.MLF对大部分红葡萄酒、一些白葡萄酒和汽酒最终的质量有重要的影响.自发进行的MLF结果往往难以预测,甚至引起葡萄酒的腐败.主要阐述引起MLF的微生物、MLF对葡萄酒品质的影响、MLF的生物学、影响MLF的因素、MLF在葡萄酒酿造中的应用等方面的研究现状,以期探索更好的控制MLF的技术.     

葡萄酒酿造及葡萄酒酵母菌种的改良

酿酒酵母是一种重要的工业微生物,是葡萄酒品质的灵魂.在无氧条件下,由葡萄转化成葡萄酒的过程申,酿酒酵母起了至关重要的作用.叙述了葡萄酒酵母与葡萄酒酿造的关系,介绍了工业化葡萄酒发酵过程中的调控手段及当前应用现代科技手段选育优良葡萄酒酵母菌种的方法,最后,对当前酿酒行业的形势和未来作出了预测和展望,     

非酿酒酵母在发酵过程中的代谢产物对葡萄酒质量的影响

非酿酒酵母广泛存在于葡萄园及酿酒环境中,虽然其在发酵过程中能产生各种异味物质影响酒的品质,但某些非酿酒酵母的代谢产物却能增强葡萄酒的香气、风味和复杂性。该文综述了非酿酒酵母在发酵过程中的代谢产物及其对葡萄酒质量的影响,以期对我国筛选非酿酒酵母用于生产具地区特色的葡萄酒提供参考。     

葡萄酒苹果酸-乳酸发酵工艺控制研究进展

本文介绍了苹果酸-乳酸发酵(MLF)的机理、引发MLF的微生物及其在葡萄酒酿造中的作用,对影响MLF环境因素和现代发酵工程技术(固定化技术)在MLF中新的应用与发展也作了阐述.     

葡萄酒中MLF的研究及技术应用

MLF（苹果酸-乳酸发酵）是葡萄酒酿造的必经步骤，可有效降低葡萄酒中的苹果酸，突出了果香。改善了口感，是葡萄酒生物降酸的主要方法。本文介绍了MLF的机理、引起MLF的微生物及其在葡萄酒酿造中的作用．对影响MLF环境因素和现代发酵工程技术在MLF中的新的应用与发展也作了阐述。     

葡萄酒苹果酸-乳酸发酵优良菌株的筛选与发酵性能分析

酒球菌是进行苹果酸-乳酸发酵（malolactic fermentation,MLF）的主要微生物,在酿酒工业中占有重要地位。该研究从山东地区栽培广泛的公酿一号葡萄酒中分离出63株微生物,最终获得5个耐酸、耐乙醇的菌株。通过16S rRNA基因序列分析鉴定为酒酒球菌。在发酵性能分析中,菌株GM1039和GM1041在模拟葡萄酒中的降酸能力显著优于对照菌株,且在发酵过程中保持了较高的活细胞数。     

微生物降酸技术在葡萄酒酿造中的应用

较全面地介绍了葡萄酒微生物降酸技术的主要内容.包括乳酸菌进行的苹果酸-乳酸发酵(MLF),裂殖酵母进行的苹果酸-酒精发酵(MAF)以及转基因酵母进行的MLF等降酸方法.本文对MLF和MAF生化反应机理、影响MLF和MAF的环境因素以及现代发酵工程技术(固定化细胞、酶技术、膜生物反应器)在葡萄酒生物降酸工艺中的应用也进行了回顾.     

非酿酒酵母在葡萄酒生产中的作用及研究进展

非酿酒酵母广泛存在于葡萄园和酿酒环境中,其代谢产物对葡萄酒的香气、风味和品质产生重要影响。本文介绍了非酿酒酵母的种类、作用、对葡萄酒成分的影响以及非酿酒酵母与酿酒酵母混合发酵的研究进展,以期为葡萄酒生产中更好的利用非酿酒酵母提供参考。     

发酵过程果酒成分对苹果酸乳酸发酵的影响

苹果酸-乳酸发酵（MLF）是果酒（葡萄酒、苹果酒）酿造中非常重要的二次发酵过程。本研究采用人工模拟果酒，研究果酒成分对MLF的影响。结果表明，葡萄糖抑制乳酸菌的MLF，果糖却有促进作用，而且果糖可解除葡萄糖对酿酒酒球菌MLF的抑制作用，果酒中葡萄糖和果糖的浓度及其比例是预测和控制MLF的重要参数；高浓度乙醇、低pH抑制乳酸菌的MLF，其抑制作用的大小与使用的菌种有关；酒中酚类物质（没食子酸和阿魏酸）对酿酒酒球菌的MLF几乎无任何显著影响；酒精发酵完成后果酒中营养的缺乏会抑制乳酸菌的MLF。     

The application of malolactic fermentation process to create good-quality grape wine produced in cool-climate countries: a review

The work presents the essence of the secondary fermentation occurring in the course of grape wines production—malolactic fermentation (MLF). The selection of wine yeast and bacteria preparations, scenario of malolactic bacteria inoculation as well as control system of the process conditions are proposed to create the specific character and style of grape wines produced in cool-climate countries, in which the acidity of grape must is often significantly enhanced and the concentration of aroma compounds is considerably low. The role played by appropriately run MLF is presented, along with the advantages and disadvantages of the process, benefits, and technological drawbacks resulting from the introduction of this procedure to the vinification process. Moreover, methods to initiate and run MLF as well as interactions occurring between microorganisms used in wine production, i.e., wine yeasts from the genus Saccharomyces and wine bacteria from the genus Oenococcus, are also presented and discussed.     

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.     

Influence of pH and ethanol on malolactic fermentation and volatile aroma compound composition in white wines

The present study investigated the influences of pH and ethanol on malolactic fermentation (MLF) and the volatile aroma profile of the subsequent white wines from Riesling and Chardonnay inoculated with two different Oenococcus oeni strains. In all cases MLF was induced after completion of alcoholic fermentation (AF). Partial MLF occurred under low pH 3.2 and high alcohol (118.3 g/L) conditions. In the cases with complete MLF, the time required for each strain varied from 13 to 61 days and was dependent on bacterial culture, cultivar and wine parameter. Chemical properties of each wine were determined after AF, complete and partial MLF. The wines showed significant differences in total higher alcohols, esters and acids that are important for the sensory profile and quality of wine. This work demonstrated that the wine matrix as well as the pH and alcohol concentration affects MLF and the final volatile aroma profile. Results indicate that changes in volatile aroma composition are not necessarily related to complete MLF and that partial MLF already has distinct influences on the wine aroma profile of white wines.     

苹果酸—乳酸细菌固定化载体的研究

利用固定化苹果酸—乳酸细菌进行苹果酸—乳酸发酵(malolactic fermatation MLF),以降低葡萄酒酸度、改善酒质的研究对葡萄酒生产具有重要意义。以31DH为供试菌株,对固定化载体的成型时间和温度进行了研究,并利用二次回归正交组合设计,优化出包埋31DH载体的理想配方。利用固定化31DH和葡萄酒中的游离31DH进行MLF,发现固定化31DH的苹果酸—乳酸酶活力明显高于游离31DH。     

Metabolism of SO₂ binding compounds by Oenococcus oeni during and after malolactic fermentation in white wine

Sulfur dioxide SO? is the key additive for the preservation of wines. Carbonyl and keto compounds in wine can bind to SO? and decrease its efficacy, resulting in higher total SO? requirements. Increased consumer demand for low sulfite and organic wines pose production challenges if SO? binders have not been properly managed during vinification. Malolactic fermentation (MLF) has been known to reduce bound SO? levels but detailed time course studies are not available. In this work, the kinetics of major SO? binding compounds and malic acid were followed during MLF in wine with 12 commercially available strains of Oenococcus oeni. Pyruvic acid, acetaldehyde and α-ketoglutaric acid were degraded to various degrees by O. oeni, but galacturonic acid was not. At the time of malic acid depletion, percent degradation of pyruvate, α-ketoglutaric acid and acetaldehyde was 49%, 14% and 30%, respectively. During MLF, the decrease in average bound SO? levels, as calculated from carbonyl metabolism, was 22%. The largest reduction in wine carbonyl content occurred in the week after completion of MLF and was 53% (107 mg/L to 34 mg/L) calculated as bound SO?. Prolonged activity of bacteria in the wines (up to 3 weeks post malic acid depletion) resulted only in reduced additional reductions in bound SO? levels. The results suggest that microbiological wine stabilization one week after malic acid depletion is an effective strategy for maximum removal of SO? binders while reducing the risk of possible post-ML spoilage by O. oeni leading to the production acetic acid and biogenic amines.     

Chemometric Analysis for the Detection of Biogenic Amines in Chilean Cabernet Sauvignon Wines: A Comparative Study between Organic and Nonorganic Production

In this work, the presence of biogenic amines (BAs) was correlated with the type of wine grape culture (traditional or organic) and their concentration in the different stages of winemaking (must, alcoholic fermentation [AF] and malolactic fermentation [MLF]). The formation of BA occurred mainly during MLF in which the percentages for putrescine, cadaverine, phenylethylamine, histamine, and tyramine were 100%, 70%, 13%, 61%, and 44% for the wines produced with traditional grapes and 100%, 94%, 25%, 88%, and 13% for the wines produced with organic grapes, respectively. In general, these latter wines exhibited a lower concentration of total amines. The principal component analysis and partial least-square discriminate analysis indicated that the generation of BA has a certain behavioral pattern in the wines analyzed, which is associated with the different stages of wine production and with the type of culture (traditional or organic) used in the wine grapes. Practical Application: Chemometrics tools can be useful as a method of characterization and classification in a global overview of the process variables involved in the development of toxic chemicals in foods, such as the production of BA in wine.     

Improvement of volatile composition of wines by controlled addition of malolactic bacteria

The effect of malolactic fermentation (MLF) on the volatile composition of red wines was studied by inoculation with selected lactic acid bacteria. Four wines were inoculated with different Oenococcus oeni (syn. Leuconostoc oenos) strains, the major malolactic species found in wines, and one was inoculated with a Lactobacillus sp. strain. A non inoculated wine was also analyzed to act as a control. Malolactic fermentation and evolution of non volatile compounds were followed by HPLC and after the depletion of the malic acid present in wine the volatile compounds were extracted and analyzed by gas chromatography with flame ionization and mass spectrometry. Wines which had undergone the MLF showed a significant increment in total higher alcohols, esters and acids that are important in the sensory properties and quality of wine.     

Identification of lactic acid bacteria isolated from South African brandy base wines

In brandy base wines, no sulphur dioxide is used and it therefore is ideal for the proliferation of lactic acid bacteria. As part of an extensive taxonomic survey within the ecological framework of South African vineyards and wineries, and the influence of naturally occurring lactic acid bacteria on the quality of wine and brandy, a total of 54 strains were isolated from grape juice and at different stages of brandy base wine production. The strains were identified using numerical analysis of total soluble cell protein patterns, 16S rRNA sequence analyses and polymerase chain reaction (PCR) using species-specific primers. The predominant species was Oenococcus oeni (22 strains), but Lactobacillus brevis (8 strains), Lactobacillus paracasei (8 strains) and Lactobacillus plantarum (6 strains) were also isolated frequently. Many of the O. oeni strains were isolated from brandy base wines after completion of spontaneous malolactic fermentation (MLF). The Lactobacillus spp. were isolated from all the different stages of brandy base wine production. Lb. plantarum was the dominant species in the juice, but disappeared during the later stages of production. However, Lactobacillus hilgardii, Lb. brevis and Lb. paracasei were also isolated from base wine after spontaneous MLF. Strains identified as Lactobacillus vermiforme were isolated during the alcoholic fermentation and after MLF have been completed. Total soluble cell protein patterns grouped O. oeni strains into two phenotypic groups. Two phenotypic clusters have also been identified for the Lb. brevis isolates. The Lb. paracasei isolates all grouped in one cluster. This is the first report of the presence of Lb. paracasei and Lb. vermiforme in brandy base wines. The presence of the Lactobacillus spp. could be correlated to the decrease in quality of the base wine and distillate, while O. oeni strains were found to have a more favourable influence on the quality of base wine and distillates. These results shed some light on the ecology and oenological influence of lactic acid bacteria (LAB) on the quality of South African brandy.     

Kinetics of sugars, organic acids and acetaldehyde during simultaneous yeast-bacterial fermentations of white wine at different pH values

Successfully inducing malolactic fermentation in the production of grape wines can be challenging, especially in wines with multiple inhibitors such as low pH values and high ethanol concentrations. In the present study, the kinetics of several chemicals of enological relevance was studied in Chardonnay vinified by traditional, consecutive alcoholic (AF) and malolactic fermentations (MLF), and simultaneous AF/MLF, where bacteria were co-inoculated with yeast. The Chardonnay must was adjusted to four pH values (3.2, 3.35, 3.5 or 3.65), and the concentrations of sugars, organic acids as well as acetaldehyde were followed throughout the fermentations. The degradation of glucose and fructose was slower at the lowest must pH value (3.2) but independent from the time point of bacterial inoculation. In all cases, malolactic conversion was faster after yeast-bacterial co-inoculation and was completed in simultaneous treatments at pH values of 3.35-3.65, and consecutive treatments at pH 3.5 and 3.65. No statistically significant difference was observed among the final acetic acid concentrations among all inoculation and pH treatments, but there was a trend towards higher acetic acid residues in wines produced by co-inoculation, especially at high pH values. Overall, simultaneous AF/MLF allowed for greatly reduced fermentation times, but the must pH remained a strong factor for fermentation success and determined the final concentration of various wine components. The time point of inoculation influenced formation and degradation kinetics of organic acids and acetaldehyde considerably, and these are of relevance for vinification decisions.