Contribution of malolactic fermentation by Oenococcus oeni and Lactobacillus plantarum to the changes in the nonanthocyanin polyphenolic composition of red wine

The changes in the nonanthocyanin phenolic composition during red wine malolactic fermentation carried out spontaneously and by four different starter cultures of the species Oenococcus oeni and Lactobacillus plantarum were examined to determine whether differences in nonanthocyanin polyphenolic compounds could be attributed to the lactic acid bacteria (LAB) strain that performs this important step of the wine-making process. The polyphenolic compounds were analyzed by high-performance liquid chromatography with photodiode array detection and HPLC with electrospray ionization-mass spectrometry detection. The malolactic cultures selected for this study were indigenous wine LAB strains from the A.O.C. Rioja (Spain). Results showed different malolactic behaviors in relation to wine phenolic compositions for O. oeni and L. plantarum, and also, a diversity was found within each group. The hydroxycinnamic acids and their derivatives, the flavonols and their glycosides, the flavanol monomers and oligomers, and trans-resveratrol and its glucoside were the main compounds modified by the different LAB. The wild LAB population exerted a greater impact in the wine content of some of these phenolic compounds than the inoculated selected monocultures of this study.     

Changes in the concentration of yeast-derived volatile compounds of red wine during malolactic fermentation with four commercial starter cultures of Oenococcus oeni

The effects of malolactic fermentation (MLF) on the concentration of volatile compounds released by yeasts during the production of red wine were investigated by inoculation with four commercial starters of Oenococcus oeni. Volatile compounds in wine at the end of MLF were extracted, analyzed by GC-MS and GC, and compared with those extracted form a noninoculated reference sample. Several esters known to play a role in the aroma profile of red wine, such as C4-C8 ethyl fatty acid esters and 3-methylbutyl acetate, were found to increase with MLF, and their final concentration was dependent on the bacterial starter employed for the induction of MLF. The overall increase of ethyl fatty acid esters was generally larger than the one observed for acetate esters. Ethyl lactate, 3-hydroxybutanoate, 2-phenylethanol, methionol, and gamma-butyrolactone were also increased by bacterial metabolism. The impact of MLF on other volatiles or red wine, including several higher alcohols, fatty acids, and nitrogen compounds, was generally negligible.     

Glyoxal/glycolaldehyde: a redox system involved in malolactic fermentation of wine

To verify the presence of glycolaldehyde in wine resulting from reduction of glyoxal after malolactic fermentation, sterilized solutions of synthetic cultures were inoculated with a lactic bacterium of the type Oenococcus oeni. Fermentation was also carried out on solutions with glyoxal added. The resulting glycolaldehyde concentrations turned out to be associated with the amounts of glyoxal present, and glyoxal was seen to decrease as glycolaldehyde increased. In addition, it was observed that glyoxal principally forms from breakdown of sugars and that reduction to glycolaldehyde is mainly promoted by bacterial activity. Finally, the ability of glycolaldehyde to induce browning of (+)-catechin in a model wine system was verified and turned out to be about 10 times higher than that of ascorbic acid.     

Hydrolysis of wine aroma precursors during malolactic fermentation with four commercial starter cultures of Oenococcus oeni

The ability of four commercial preparations of Oenococcus oeni lactic acid bacteria (EQ 54, Lalvin OSU, Uvaferm Alpha, and Lalvin 31) to hydrolyze wine aroma precursors was evaluated by measuring the concentration of free and bound aroma compounds at the end of malolactic fermentation carried out in model wines containing a mixture of glycosides extracted from Muscat wine. At pH 3.4 there was a decrease in glycosylated compounds matched by a concomitant increase in free forms in all starter cultures tested. When malolactic fermentation was carried out at pH 3.2, a significant decrease in the ability to hydrolyze aroma precursors was observed for two of the cultures tested (Uvaferm Alpha and Lalvin 31). Large differences in the extent of hydrolysis and in the specificity of this activity toward specific aroma precursors were observed and appeared to be related to the chemical structure of the aglycon as well as to individual characteristics of each starter culture. The amounts of glycosylated aroma compounds released during malolactic fermentation suggest that O. oeni can alter the sensory characteristics of wine through the hydrolysis of aroma precursors.     

Effect of beta-glycosidase activity of Oenococcus oeni on the glycosylated flavor precursors of Tannat wine during malolactic fermentation

Under traditional wine-making conditions, this work examines the beta-glycosidic activity of Oenococcus oeni on glycosylated aroma compounds of Tannat wines during malolactic fermentation (MLF) by comparing the changes on selected aglycones liberated. MLF diminished the content of all the glycosylated compounds. The level of the free aroma components was slightly modified by the action of the malolactic fermentation so that the cleavage of the glycosidic linkage by the beta-glycosidic activity of O. oeni did not appear to increase significatively the aglycone contents. The consequences of further chemical rearrangements of the algycones under wine conditions were explored using synthesized glycoconjugates on synthetic medium. Bacteria could also be responsible for the cleavage of aroma glycosylated compounds, being the aglycone adsorbed on polysaccharides or peptidoglycans and was released into the external medium. This hypothesis was studied through the evaluation of a stable arrangement of aroma compounds with polysaccharides produced by lactic acid bacteria. A possible retaining of free-made aroma compounds into the whole cells of O. oeni was also investigated through cell culture analysis. Through the results obtained, we assume stable linkage of aroma compounds with bacterial polysaccharides.     

Effect of flash release and pectinolytic enzyme treatments on wine polysaccharide composition

Various treatments, including flash release and addition of pectic enzymes, have been proposed to enhance degradation of grape berry cell walls and extraction of aroma and phenolic compounds into the wines. The effect of flash release and enzyme treatment used separately or in combination on wine polysaccharide composition was studied. The flash release process increased extraction of polysaccharides originating from grape berry cell walls, that is, polysaccharides rich in arabinose and galactose (PRAGs) and type II rhamnogalacturonan (RG-II), thus yielding enriched wines. Increasing the duration of high-temperature exposure before the flash release treatment further increased extraction of polysaccharides. However, the wine obtained by pressing immediately after flash release and fermenting in the liquid phase contained lower amounts of grape polysaccharides, indicating that their extraction required skin maceration. The use of enzymes without or with flash release modified the composition and the structure of pectic polysaccharides. In particular, it induced the loss of PRAG terminal arabinose residues.     

Changes in amine concentrations during aging of red wine in oak barrels

This investigation studied the evolution of amines in red wines made with Merlot variety, during aging in American oak barrels (Quercus alba) and in French oak barrels (Quercus sessilis) from the Allier and Nevers regions. From the results obtained it was observed that the evolutions of the amines were similar in all three types of oak woods. Histamine and tyramine were produced at the beginning of the aging process, although they were not accumulated in the wines, probably due to their degradation. Putrescine was the most abundant amine in the wines; its concentration increased to an important extent during aging as it did not undergo degradation. The concentration of cadaverine increased slightly at the first stage of aging and, like putrescine, did not degrade at all. The volatile amines showed slight variations during aging, although in no cases were high accumulations observed in the wines. Dimethylamine and isobutylamine were degraded during storage in the barrels.     

Influence of wine pH on changes in color and polyphenol composition induced by micro-oxygenation

The presence of oxygen in red wine leads to the transformation of ethanol into ethanal, which after capturing a proton will react with flavanols to start the process of forming ethyl bridges between flavanols and between flavanols and anthocyanins. Wine pH also conditions the equilibrium between the different anthocyanin structures and may thus affect anthocyanin reactivity. Consequently, the aim of this paper was to study how the pH can affect the changes induced by micro-oxygenation in two wines with different phenolic composition. The differences between micro-oxygenated wines and their controls were, in general, greater when the pH was more acidic. Specifically, the differences between micro-oxygenated wines and their corresponding controls in terms of color intensity, anthocyanin concentration, PVPP index, ethyl-linked pigments, B-type vitisins, polymeric pigments, and ethylidene-bridged flavanols were greater at lower pH. In contrast, the effects of micro-oxygenation when the pH was less acidic were much less evident and sometimes practically nonexistent. These results demonstrate for the first time that the pH of the wine has a great influence on oxygen-induced changes of color and phenolic compounds.     

Multivariate evaluation of changes induced in red wine characteristics by the use of extracting agents

The aim of the present work was to study the effect of both vintage and the use of four types of pectinolytic enzymatic preparations on the quality of red wine using factor analysis. We also studied the evolution of the factors obtained along two years of storage of the wine. The results obtained from the factor analysis revealed that the addition of pectinolytic enzymes enriched the phenolic composition and elicited an improvement in the visual aspect of the wine, which persisted during the storage period considered.     

Changes in nitrogen compounds in must and wine during fermentation and biological aging by flor yeasts.

Urea, ammonium, and free amino acid contents were quantified in a must from Vitis vinifera cv. Pedro Ximenez grapes and in fermented wine and after a short aging of this wine by Saccharomyces cerevisiae race capensis yeast under variable oxygen availability conditions. The previous compounds were also determined in a wine in which the nitrogen source was depleted by the same race of flor yeast (old wine) and also following the addition of ammonium ion, L-glutamic acid, and L-proline. Under specific conditions such as low oxygen level and the absence of some nutrients, the yeasts release some amino acids including L-threonine, L-tryptophan, L-cysteine, and L-methionine to the medium. These amino acids must originate primarily in a de novo synthesis from ethanol that regenerates NAD(P)+. On the basis of these results, the yeasts may be able to use amino acids not only as nitrogen sources but also as redox agents to balance the oxidation-reduction potential under conditions of restricted oxygen, when electron transport along the respiratory chain may be hindered or limited.     

Berry integrity and extraction of skin and seed proanthocyanidins during red wine fermentation

In this study, microscale fermentations were conducted on Vitis vinifera L. cv. Merlot. Five treatments were established varying from 0-100% crushed fruit (25% increments x 5 replicates). Caps were kept submerged throughout the experiment, and fermentation temperatures were maintained at 25 degrees C. Samples were collected throughout fermentation and from the free run and press wine at the time of pressing. Proanthocyanidins were determined by acid-catalyzed depolymerization in the presence of phloroglucinol, followed by reversed phase, high performance liquid chromatography (RP-HPLC). Total proanthocyanidin extraction increased with time in all treatments. In addition, crushing increased the rate at which proanthocyanidins were extracted. When the extraction of skin and seed proanthocyanidins were monitored separately, skin proanthocyanidin extraction rate exceeded that for seed proanthocyanidins and followed a Boltzmann sigmoid extraction model. The highest proanthocyanidin concentration for skin (435 mg/L) and seed (344 mg/L) was observed for the 75% crushed fruit treatment at the time of pressing (17 days). The highest skin proanthocyanidin proportion (79%) was observed for the 75% crushed fruit treatment on day 9 with a total proanthocyanidin concentration of 439 mg/L. For all treatments, skin proanthocyanidin extraction reached a plateau concentration prior to pressing, with the plateau concentration increasing with crushing. Seed proanthocyanidin concentration increased throughout maceration.     

Vineyard and fermentation studies to elucidate the origin of 1,8-cineole in Australian red wine

Preliminary investigations revealed that the proximity of Eucalyptus trees to grapevines can directly influence the concentration of the aroma compound 1,8-cineole present in the corresponding red wines. For two different vineyards, the closer the grapevines were to the trees, the greater was the amount of 1,8-cineole in the wines elaborated from those grapes. This led us to carry out further studies to quantify the levels of 1,8-cineole found in grape berries, leaves, and stems at set distances from Eucalyptus trees over multiple vintages. Generally, the highest concentration of 1,8-cineole was found in the grapevine leaves, followed by grape stems and then grapes. In each sample type, we observed greater concentrations of 1,8-cineole in samples closer to the trees. Various fermentation treatments carried out with Shiraz grapes showed that matter other than grapes (MOG, e.g., Eucalyptus or grape leaves) could contribute significant amounts of 1,8-cineole to the finished wines. These studies confirmed that vineyard position and winemaking conditions can determine the 1,8-cineole concentration in red wine. The fermentation study also showed for the first time that the concentration of rotundone in red wine can be strongly influenced by grapevine leaves and stems in the ferment.     

Wine volatile and amino acid composition after malolactic fermentation: effect of Oenococcus oeni and Lactobacillus plantarum starter cultures

Red wine amino acids and volatile compounds were analyzed before and after malolactic fermentation carried out by four different starter cultures of the species Oenococcus oeni and Lactobacillus plantarum. The purpose of this study was to determine whether differences can be attributed to the lactic acid bacteria strain used in this important step of the wine-making process. The malolactic cultures selected for this study were indigenous wine lactic acid bacteria strains. The data were evaluated using different multivariate analysis techniques. Results showed different malolactic behaviors for O. oeni and L. plantarum and significant metabolic differences between both species. A degree of diversity was found within each lactic acid bacteria group, since wines presented specific characteristics depending on the lactic acid bacteria strain used. In all cases, malolactic fermentation seemed to modify the amino acid and volatile composition of the wine.     

微孔膜在红葡萄酒过滤澄清中的应用研究

研究了微孔膜过滤(CMF)系统在红葡萄酒过滤澄清工艺中的适用性.实验采用德国制造的微孔滤膜,测定了过滤膜的工作曲线、比较了不同清洗方式对膜通量的影响,以及过滤前后红葡萄酒主要理化、感观品质变化,以此确定CMF在红葡萄酒过滤澄清中的性能.实验发现:1)CMF过滤下胶后和冷冻后葡萄酒,流量衰减缓慢,表现出良好的过滤性能;2)经过2% NaOH热碱液(55～60℃)清洗20 min后过滤流量恢复良好,显著改善了过滤中期膜的性能;3)过滤初期进行流量(压力)调节有利于CMF良好过滤性能的保持,CMF过滤下胶后和冷冻后红葡萄酒的初期流量分别为50和 66.6 L/(h·m2)为宜;4)经过CMF过滤后,提高了葡萄酒的品质和稳定性,除还原糖、总SO2和游离SO2等指标稍有降低外,其它主要理化指标变化很小,感观分析发现在香气保留方面优于硅藻土过滤.本实验结果为微孔膜过滤应用于红葡萄酒澄清提供了依据和基础工艺参数.     

Fate of pesticides during the winemaking process in relation to malolactic fermentation

The effect of red wine malolactic fermentation on the fate of seven fungicides (carbendazim, chlorothalonil, fenarimol, metalaxyl, oxadixyl, procymidone, and triadimenol) and three insecticides (carbaryl, chlorpyrifos, and dicofol) was investigated. After malolactic fermentation using Oenococcus oeni, which simulated common Australian enological conditions, the concentrations of the active compounds chlorpyrifos and dicofol were the most significantly reduced, whereas the concentrations of chlorothalonil and procymidone diminished only slightly. The effect of these pesticides on the activity of the bacteria was also studied. Dicofol had a major inhibitory effect on the catabolism of malic acid, whereas chlorothalonil, chlorpyrifos, and fenarimol had only a minor effect.     

Relationship between red wine grade and phenolics. 2. Tannin composition and size

Commercial red wines ( Vitis vinifera L. cv. Shiraz) produced during the 2009 vintage underwent winemaker assessment for allocation grade soon after production. The wines were then subjected to phenolic analysis to measure wine color (total anthocyanin, SO(2) nonbleachable pigment, and wine color density) and tannins (concentration, composition, and average degree of polymerization). A positive relationship was found between wine phenolic concentration and projected bottle price. Tannin compositional analysis suggested that there was specifically a relationship between wine grade and skin-derived tannins. These results suggest that maximization of skin tannin concentration and/or proportion is related to an increase in projected wine bottle price.     

干红葡萄酒发酵尾气CO2浓度变化规律数学模型的建立

通过对干红葡萄酒实际生产过程从接入酵母菌到自流酒分离这一发酵过程排气CO2浓度的现场测试,发现干红葡萄酒发酵过程排气CO2浓度变化的规律,为软测量技术在葡萄酒生产中应用做一些基础研究.干红葡萄酒发酵过程排气CO2浓度变化的规律为在葡萄入罐接入酵母菌后的2h内几乎没有CO2气体排出;之后CO2排气浓度以很大的速度增加,当浓度约达到90%以上时,增加速度开始缓慢且维持在高浓度状态,甚至达到极限值100%;建立了排气CO2浓度随时间变化规律的数学模型为生长曲线函数--逻辑斯蒂(Logistic)函数.     

In vitro fermentation of a red wine extract by human gut microbiota: changes in microbial groups and formation of phenolic metabolites

An in vitro batch culture fermentation experiment was conducted with fecal inocula from three healthy volunteers in the presence and absence of a red wine extract. Changes in main bacterial groups were determined by FISH during a 48 h fermentation period. The catabolism of main flavonoids (i.e., flavan-3-ols and anthocyanins) and the formation of a wide a range of phenolic microbial metabolites were determined by a targeted UPLC-PAD-ESI-TQ MS method. Statistical analysis revealed that catechol/pyrocatechol, as well as 4-hydroxy-5-(phenyl)-valeric, 3- and 4-hydroxyphenylacetic, phenylacetic, phenylpropionic, and benzoic acids, showed the greatest increases in concentration during fermentation, whereas 5-(3'-hydroxyphenyl)-γ-valerolactone, its open form 4-hydroxy-5-(3'-hydroxyphenyl)-valeric acid, and 3,4-dihydroxyphenylacetic acid represented the largest interindividual variations in the catabolism of red wine polyphenols. Despite these changes, microbial catabolism did not produce significant changes in the main bacterial groups detected, although a slight inhibition of the Clostridium histolyticum group was observed.     

Evolution of phenolic composition of red wine during vinification and storage and its contribution to wine sensory properties and antioxidant activity

The objective of this work was to study the evolution of the phenolic composition of red wine during vinification and storage and its relationship with some sensory properties (astringency and bitterness) and antioxidant activities. Thus, red wine was made by a classic vinification method with Castela?o and Tinta Miu?da grapes (Vitis vinifera L.) harvested at maturity (3:2; w/w). Samples were taken at 2 and 7 days of maceration, at second racking, at the time of bottling and at 6 and 14 months after bottling. The total polyphenols extract (TPx) in each sample was isolated by column chromatography. The phenolic composition (anthocyanins and proanthocyanidins), in vitro antioxidant activity, and sensory property (astringency, bitterness) of the isolated TPx from different winemaking stages were evaluated through high-performance liquid chromatography-diode array detection, 1,1-diphenyl-2-picrylhidrazyl radical test, ferric reducing antioxidant power assay, total phenolic index, MWI (polyphenol molecular weight index), TSA (tannin specific activity), and sensory panel tasting. The results showed that the phenolic composition of red wine varied significantly during winemaking. The intensity of astringency (IA) and the intensity bitterness (IB) of the isolated TPx from different winemaking stages increased from 2 days of maceration until second racking and then decreased. Furthermore, MWI and TSA are positively correlated with IA and IB. The in vitro antioxidant activity of the isolated TPx from different winemaking stages maintained unchanged after alcoholic fermentation, which was independent of the variation of phenolic composition and sensory properties.