A review on micro-oxygenation of red wines: Claims,benefits and the underlying chemistry

Micro-oxygenation is the process of deliberately introducing minute, measured amounts of oxygen into wines, with the aim of bringing about desirable changes in colour, aroma and texture. It involves the use of specialised equipment to regulate the doses of oxygen that are administered. The main claims concerning the effect of micro-oxygenation in wines include an improvement in the health of yeasts during alcoholic fermentation, better wine colour and stability, more complex organoleptic characteristics, a reduction in sulphur off-odours and, also, the ability to mimic the reactions that occur during wine oak-ageing. In this paper we review the different claims and the chemistry that underlies these claims and discuss the most important factors that should be taken into account when applying micro-oxygenation and the most recent innovations.     

Influence of alcoholic and malolactic starter cultures on bioactive amines in Merlot wines

The influence of alcoholic and malolactic fermentations on the levels of amines in Merlot wines was investigated. Saccharomyces bayanus, S. cerevisiae, Lactobacillus plantarum, Oenococcus oeni (DSM 7008 and 12923) and spontaneous fermentations were used. Four of the 10 amines investigated were detected: spermidine, serotonin, putrescine and cadaverine. When considering the factors independently, the malolactic bacteria significantly affected the levels of serotonin and total amines, whereas the fermentation yeasts significantly affected the levels of spermidine (two way Kruskal–Wallis, p ? 0.05). Spermidine levels were significantly higher in wines produced with S. cerevisiae. Significantly higher serotonin levels were found in wines made with L. plantarum. Putrescine and cadaverine were not detected in wines produced by spontaneous alcoholic fermentation or by L. plantarum. There were significant differences in alcohol content, total and volatile acidity, sulphite levels and taste quality among wines (Tukey test, p ? 0.05).     

苹果乳酸发酵生产葡萄酒

二次发酵-苹果乳酸发酵（MLF）在葡萄酒生产过程中起非常重要的作用.酿酒需要选择合适的酿酒酵母和细菌,乳酸菌接种方案以及工艺条件控制系统.本文介绍了MLF发酵过程的优缺点、效益和技术缺陷.讨论了启动和运行MLF的方法及葡萄酒生产过程中各种微生物之间的相互作用.微生物主要是指酵母菌属中的酿酒酵母和酒类酒球菌属中的酿酒细菌.     

Oak barrel maturation vs. micro-oxygenation: Effect on the formation of anthocyanin-derived pigments and wine colour

The objective of this study was to check whether micro-oxygenation (MO) could mimic oak barrel ageing as regard the effect on wine colour. A red wine was submitted to micro-oxygenation for three months while another lot from the same wine was matured in oak barrels for three or six months. After these times, oak-matured and micro-oxygenated wines were bottled and analyzed six months later. The chromatic characteristics of these wines were also compared with those of a control wine that remained in a stainless steel tank all the time. Anthocyanins and anthocyanin-derived compounds were studied by LC–ESI-MS. Monomeric anthocyanins and other compounds including direct anthocyanin–flavanol adducts, ethyl-linked anthocyanin–flavanol compounds, and pyranoanthocyanins were detected. The application of MO for three months produced wines with a lower concentration of monomeric anthocyanins and a higher concentration of vitisin-related pigments than the control wine, the oak mature wines showing similar results than MO wines when aged for the same period of time. Differences were also observed in the chromatic characteristics, the micro-oxygenated and the oak matured wines showing a higher colour intensity than control wine. However, after six months in bottle differences were found between the micro-oxygenated wines and oak matured wines, the latter showing a more stable colour, probably due to the beneficial effects of compounds extracted from the wood (e.g. ellagitannins or wood aldehydes).     

不同酒类酒球菌苹果酸—乳酸发酵对葡萄酒中氨基酸的影响

不同酒类酒球菌茵株完成MLF后,葡萄酒中氨基酸均发生显著变化:种类增多,诸多氨基酸含量提高。SD-2a发酵酒样中的丙氨酸和谷氨酸、SD-1b发酵酒样中甘氨酸、丝氨酸和脯氨酸、SD-2h酒样中谷氨酸、甘氨酸、丝氨酸、脯氨酸含量明显增加;含量呈极显著增加的氨基酸为:在SD-2h发酵酒样中的丙氨酸、在SD-1b发酵酒样中的丙氨酸、缬氨酸和谷氨酸;对照菌株31DH发酵酒样中各种氨基酸的增减没有达到显著水平。葡萄酒学院分离筛选的3个菌株发酵酒样中的精氨酸含量增加,而对照菌株31DH则有所降低。因此,3个菌株代谢特性良好,在葡萄酒中不会导致致癌物质——氨基甲酸乙酯的前体物脲、瓜氨酸等的过多合成。鉴于各种氨基酸独特的生化和生理特性,3株酒类酒球菌菌株完成MLF后,氨基酸种类、含量的增加可以提高葡萄酒的营养价值和保健功能。     

Partial characterization of peptides from red wines. Changes during malolactic fermentation and ageing with lees

The peptide fraction of an industrially manufactured red wine has been studied during malolactic fermentation, carried out in stainless-steel tanks or in the barrel and ageing in the barrel, with or without lees, for 12 months. Peptides were fractionated using Sephadex LH-20 and Cosmosil 140 C₁₈-OPN columns, giving two fractions in relation to peptide polarity. The most important changes were detected during malolactic fermentation and during the ageing in barrel with lees. The peptides present in the wine could be glycopeptides from grape or yeast. Most amino acids in the most polar peptides were aspartic acid and/or asparagine, glutamic acid and/or glutamine, serine, glycine, α-alanine and tyrosine and, in the less polar fraction, were glycine, α-alanine and leucine. The amino acid distribution is most different in the most polar fraction, among the studied wines, owing to autolysis and hydrolysis of the polypeptides and proteins.     

不同乳酸菌接种量进行苹果酸-乳酸发酵对葡萄酒质量的影响

本文将优良酒类酒球菌茵系SD-2h(Oenococcus oeni)接种到赤霞珠干红葡萄酒原酒中进行苹果酸-乳酸发酵,研究了不同接种量对葡萄酒质量的影响.结果表明,随着接种量的增大,苹果酸-乳酸发酵速度加快,挥发酸逐级升高.不同接种量对葡萄酒的色泽产生不同影响,苹果酸等有机酸含量差异不大,而柠檬酸含量差异显著.     

Effect of refermentation conditions and micro-oxygenation on the reduction of volatile acidity by commercial S. cerevisiae strains and their impact on the aromatic profile of wines

Herein, we evaluate the applicability of previously characterized commercial and indigenous Saccharomyces cerevisiae strains and non-S. cerevisiae species for the deacidification of white and red wines at a pilot scale. The effect of the refermentation process (mixture of acidic wine with musts from freshly crushed grapes or with residual marc) as well as micro-oxygenation (MO) on acetic acid removal efficiency and wine aromatic composition was also assessed in a red wine. The commercial strains S26 and S29 efficiently reduced both acetic acid (43 and 47%, respectively) and sugar (100%) after 264 h of refermentation of an acidic white wine that was supplemented with grape must. Similar results (60-66% of acetic acid removal) were observed for red wine deacidification using grape must, independently of MO. When residual marc was used for deacidification, strain S26 removed 40% of acetic acid, whereas strain S29 did not initiate refermentation with or without MO. Wines obtained by refermentation with the must had significantly lower acetic acid and a higher total SO₂ concentration in comparison to the wines deacidified by the grape marcs. The volatile aroma compound's composition of deacidified red wines was dependent on the refermentation process used, rather than on MO. The marc-deacidified wine obtained by the use of strain S26 and without MO achieved the best sensory classification. When data from all analytical and sensory evaluation were combined, Principal Component Analysis (PCA) separated the wines into three distinct groups according to the strain and the refermentation process independently of MO. We successfully established an efficient and cheap enological solution for the rectification of volatile acidity of wines.     

Malolactic fermentation in four varieties of sea buckthorn (Hippophaë rhamnoides L.)

Malolactic fermentation (MLF) used in winemaking was applied to four varieties of sea buckthorn (Hippophaë rhamnoides L.). Sensory properties and chemical components of fermented and unfermented juices were studied in order to see whether the MLF can have an effect on sensory quality of sea buckthorn and if there are differences between varieties. The juices were inoculated with unadapted Oenococcus oeni at a cell density of 10⁹ CFU/mL and the fermentation was performed over 18 h at 28 °C. The fermentation decreased sourness and astringency in the samples, and fruity flavor as well as fermented flavor were increased. However, the ML reaction was different between the varieties. The size of the reaction was not proportional to the initial pH or malic acid content of the juice. Larger the ML reaction, more changes were observed in the sensory properties.     

Malolactic fermentation in sea buckthorn (Hippophaë rhamnoides L.) juice processing

Malolactic fermentation (MLF) traditionally used in winemaking was applied to sea buckthorn to reduce the high sourness of the berry juice. Chemical and microbiological aspects, as well as sensory properties of the juice during MLF were studied in order to develop an optimal process. In 1:1 water diluted juice with malic acid content of 15 g/l and pH 2.8, efficient conversion of l-malic acid to l-lactic acid was achieved with direct inoculation of unadapted Oenococcus oeni at a cell density of 10⁹ CFU/ml. The rapid malic acid degradation was performed by non-growing bacterial cells without loss of sugars, vitamin C, or pulp oil. More than 50% of the initial malic acid was metabolized to lactic acid and CO₂ already in 12 h of fermentation and a significant decrease in sourness and astringency was noticed. In 24 h fermentation, pH value was increased to 3.1 and only 3 g/l malic acid remained in the juice. Prolonged fermentation had only minor effect on malolactic reaction, but off-flavor of the juice began to increase.     

Effect of artificial ageing using different wood chips on the antioxidant activity,resveratrol and catechin concentration,sensory properties and colour of two Greek red wines

Two Greek red wines (Syrah and Cabernet) were artificially aged with different wood chips (white oak, red oak, Turkey oak, chestnut, Bosnian pine, cherry, common juniper, common walnut, white mulberry, black locust and apricot). The influence of each wood species was tested for up to 20 days. The optimum duration for the extraction of total polyphenols was 20 days (Syrah) or 10 days (Cabernet) when chips of white oak, chestnut, cherry, white mulberry, black locust and apricot where used. Resveratrol and catechin concentrations ranged within the limits previously reported in literature. A high antioxidant activity was established after 10 days of artificial ageing. The sensory evaluation showed that the best results were produced by the apricot chips after 5 days (Syrah) or black locust and apricot after 5 days (Cabernet). Colour was seen to increase with both time of ageing and number of wood chips added.     

葡萄酒中的生物胺的生产与工艺控制

生物胺存在于多种发酵食品中，人体吸收过量的生物胺后会引起不良的生理反应，在葡萄酒苹果酸－乳酸发酵（MLF）过程中，有些乳酸菌能够对氨基酸脱羧产生生物胺。利用PCR与DNA探针技术能够快速检测葡萄酒中的组胺产生菌。工艺上采用接种进行MLF，并在MLF完成后对乳酸菌进行有效清除，可以显著降低葡萄酒中生物胺的含量。     

Micro-oxygenation and oak chip treatments of red wines: Effects on colour-related phenolics,volatile composition and sensory characteristics. Part II: Merlot wines

The character of Merlot wines after the treatments of micro-oxygenation and subsequent chips addition, as regards the colour-related phenolics, volatile composition and sensory characteristics, was studied. An increase in the degree of polymerisation of red pigments and a decrease in the value of the red component of the colour (a^*) and the degree of co-pigmentation were observed. The concentrations of monomeric anthocyanins and anthocyanin-derived pigments, such as hydroxyphenyl-pyranoanthocyanins and anthocyanin-ethyl-flavan-3-ol adducts, significantly decreased. With regard to the wine aroma, the micro-oxygenation produced a decrease of some esters, alcohols and benzenic compounds and increased some terpenes and C₁₃-norisoprenoids. With regard to sensorial analysis, micro-oxygenation treatment resulted in higher scores for the red fruit and spicy attributes and caused the presence of new attributes (nutty and sweet fruit). This technique produces a lower level of the typical oak chip aromas (vanilla and woody) in Merlot 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.     

Differences in the phenolic composition and sensory profile between red wines aged in oak barrels and wines aged with oak chips

The aim of this study was to evaluate the similarities or differences in the phenolic composition and the sensory characteristics between wines traditionally aged in new French and American barrels for different periods of time, and wines aged for 30 days with different kinds (different geographical origin al toasting degree) of oak chips. This study was carried out with two grape varieties, Mencía and Tinta del País, and in two consecutive vintages. The results obtained indicated that it was not possible to obtain wines aged with chips with sensory characteristics similar to those aged for a long time in new barrels, independently. However, the results showed that the use of oak chips could be a good alternative for elaborating young wines with slight olfactory and gustative wood notes quite similar to wines aged in new barrels for short periods of time (about three months).     

Presence of polycyclic aromatic hydrocarbons in woody chips used as adjuvant in wines, vinegars and distillates

Samples of 15 commercially available batches of wood chips, used in alcoholic beverage industry, were extracted and analyzed for their content in polycyclic aromatic hydrocarbons (PAHs). Total amounts of PAHs varying between 0.96 and 15.1 ng/g of wood were found, with medium to low MW compounds being mainly present. Carcinogenic benzo[a]pyrene was found in such a value, however, not alarming if maximum mandatory levels in food are considered.PAHs content in chips was unaffected by wood origin, size or toasting level while further investigations dealing with phenomena occurring during the wood seasoning could be necessary.     

苹果酸-乳酸发酵接种研究

本文以四个酿酒葡萄品种和酒类酒球菌(Oenococcus oeni)31DH为材料，进行了苹果酸-乳酸发酵(MLF)接种研究。结果表明，MLF应在酒精发酵结束后接种，接种量以10^7cfu／ml为宜，品种间MLF的速度受接种量的影响。适宜的接种环境条件为：温度18-21℃，pH不低于3．2，总SO2浓度不超过50mg／L。本文还对MLF接种时间的确定和接种量选择问题进行了探讨。