葡萄酒后处理阶段溶解氧变化研究

研究了葡萄酒下胶、粗滤、冷冻、细滤、纸滤、膜滤、灌装及瓶贮等后处理阶段中溶解氧的变化情况。结果表明冷冻过程和灌装过程中葡萄酒中的溶解氧含量大增,增幅达10倍以上;粗滤导致酒的溶解氧轻微增加,但纸板精滤会减少酒中溶解氧;瓶贮过程中溶解氧含量会逐步下降,灌装前酒中溶解氧为0.08mg/L,灌装后为0.83mg/L,2个月后变为0.56mg/L,4个月后变为0.16mg/L,与橡木桶贮存水平类似。     

二氧化硫在葡萄酒酒精发酵过程中的变化

SO2在葡萄酒中有不可取代的作用,以酒精发酵为背景,通过对不同糖度条件下,发酵醪液中SO2的消耗进行测定,得出SO2的变化规律。测定表明,4个不同糖浓度的样品在酒精发酵过程中,SO2的变化均满足以下规律:游离SO2消耗迅速,在降至7.5mg/L左右时,趋于恒定;总SO2的变化较小,降至86mg/L左右趋于恒定。这说明,发酵基质中糖浓度对游离硫和总硫的变化影响不大。     

葡萄酒酿造过程中内部因素对颜色稳定性影响分析

以酿酒葡萄赤霞珠果实进行葡萄酒酿造,通过分光光度计检测葡萄酒中花色苷的吸光度、色度的变化来阐述红葡萄酒发酵过程中内部变化(SO2浓度、金属离子、酒精度)对葡萄酒颜色稳定性的影响。结果表明:随着SO2、金属离子度的不断增加,葡萄酒样品吸光度值逐渐降低,颜色逐渐变浅,SO2在40 mg/L浓度下的葡萄酒色度几乎没有变化,偏大则造成褪色。酒精度在10%~12%(体积分数)时,对果皮中的花色苷的浸提效果越好,色泽稳定性越好,葡萄酒的颜色加深。     

中途抑制发酵法制备葡萄酒的研究

利用中途抑制发酵法可制得低酒精度的干型葡萄酒,也可制得糖度较高的甜葡萄酒.以浓缩葡萄汁为原料,采用直接加入SO2、离心分离酵母,并加入SO2、加热处理、添加酒精或白兰地(蒸馏葡萄酒)等方法,在酒精发酵中途抑制发酵.结果表明,酒精度达到低醇葡萄酒的要求时,加入≥200 mg/L的SO2能停止葡萄酒发酵;离心条件为4000 r/min,10 min分离酵母,再加入≥150 mg/L的SO2也能中止发酵;加热温度≥65℃,10 min后同样可以抑制葡萄酒发酵,再加入150 mg/L SO2可得到低醇葡萄酒.     

赤霞珠葡萄酒酿造过程中白藜芦醇的变化

赤霞珠干红葡萄酒发酵期间葡萄酒中的白藜芦醇的变化情况采用HPLC直接进样方法检测。主发酵温度控制在26℃~28℃,主发酵前添加60 mg/L的二氧化硫,在后发酵时补充加入10 mg/L的SO2,能有效的降低白藜芦醇的损失。经过苹果酸-乳酸发酵后白藜芦醇总量略微有点提高,达到4.98 mg/L。     

中国主产干红葡萄酒中氨基酸含量对照与探讨

测定了市售国内葡萄主产地的 8个主要品牌干红葡萄酒中的游离氨基酸含量 ,发现不同葡萄品种之间游离氨基酸含量差别很大 ,新疆天山北坡地区所产干红葡萄酒中含量最高 ,达到 15 0 8mg/L ,与美国加州优质干红葡萄酒相当 ,其余品牌大多数在 70 0～ 1 1 0 0mg/L范围内变化 ,有 2个样品含量低于 30 0mg/L。L 脯氨酸是所有葡萄酒中氨基酸的主体 ,也是各样品含量差异最大的氨基酸 ,这与葡萄品种、气候、发酵工艺及酒的陈酿时间有关。     

赤霞珠干红葡萄酒中甲醇、乙酸乙酯、高级醇含量的测定

采用毛细管气相色谱法测定了不同年份赤霞珠干红葡萄酒中甲醇、乙酸乙酯、高级醇的含量。结果表明,随着贮藏时间的延长,甲醇含量逐渐降低,乙酸乙酯含量逐渐升高,高级醇含量逐渐升高,异戊醇含量最高,约占所测得高级醇总量的69%。测定的样品中甲醇含量为122.37~207.12 mg/L,乙酸乙酯含量为15.24~37.92 mg/L,高级醇总量为338.73~399.62 mg/L。对比分析贮藏时间对葡萄酒甲醇、乙酸乙酯、高级醇的影响,为提升葡萄酒品质,促进葡萄酒行业的发展奠定了基础。     

国产葡萄酒中生物胺组成与含量分析

通过对国产葡萄酒产品中生物胺组成和含量的检测分析,了解国产葡萄酒中生物胺含量现状。采用GB/T 5009.208—2008方法,对国内市售的250个国产葡萄酒样品中8种生物胺(色胺、苯乙胺、腐胺、尸胺、组胺、酪胺、精胺和亚精胺)含量进行检测。结果显示,国产葡萄酒样品中8种生物胺含量范围分别为色胺0~32.78 mg/L,苯乙胺0~48.20 mg/L,腐胺0~46.60 mg/L,尸胺0~9.38 mg/L,组胺0~14.37 mg/L,酪胺0~14.60 mg/L,精胺0~12.73 mg/L,亚精胺0~0.50mg/L;葡萄酒样品中检出率最高和最低的生物胺分别为腐胺和精胺,检出率分别为88.4%和50.0%,组胺检出率为52.8%;98.8%的葡萄酒样品中组胺含量低于10 mg/L,98.0%的葡萄酒样品中酪胺含量低于10 mg/L。同其他种类葡萄酒相比,干红葡萄酒样品中生物胺含量相对较高,但与欧洲葡萄酒传统酿造国家的同类产品含量水平一致。国产葡萄酒中生物胺含量水平符合食品安全要求,具有较好的饮用安全性。     

三叶木通果酒酿造工艺研究

参照较为成熟的葡萄酒酿造工艺进行三叶木通果酒的酿造,以期为生产实际提供参考。以三叶木通果实为原料,将其打浆、去籽、过滤后,选用陈酿型干红葡萄酒专用酵母进行发酵酿造三叶木通果酒。研究表明,发酵温度23~28℃,主发酵时间9 d,果胶酶用量20 mg/L,SO2用量50 mg/L,调整果浆的糖度至22%,酵母接种量0.2 g/L,皂土用量0.8 g/L,得到成品三叶木通果酒。成品酒液清亮透明,酒色淡黄,无悬浮物,酒香浓郁;酸度为10.61 g/L,多酚含量0.116 mg/m L,并具有良好的自由基清除活性。     

天然木塞对干红葡萄酒品质的影响

对七种天然木塞(分别编号为1#～7#)的综合性能进行研究,通过检测木塞外观质量及物理特性,监测瓶贮期间是否漏酒、胀塞,酒液浸塞高度,瓶内游离氧,酒液中溶解氧、游离SO₂、色度、色调,感官评价等多项指标,分析不同天然木塞的优缺点及对瓶装葡萄酒品质的影响。结果表明,2#木塞表面光洁、端面平整、色泽均一;木塞密封性能2#>7#>6#>5#>4#>3#>1#。2#木塞塞孔径最小、皮孔深度最浅、皮孔条数最少,尺寸误差最小、回弹能力最强,瓶贮36个月后,瓶内顶端空间游离氧最低(0.13 mg/L),酒液中溶解氧最低(0.19 mg/L),游离SO₂最高(14 mg/L),色度最低(5.6),色调最低(0.96),感官品质最高(92分)。因此,2#木塞的性能指标及密封酒液的品质最好。     

Investigation of molecular changes in wine during storage in refrigerated cabinets

Wine is a complex chemical mixture that is bound to change over time. Most wines are produced for consumption within months. Some premium wines are meant to be maturated for several years or even decades after bottling. The post-bottling evolution and the longevity of a wine depends on its initial chemical composition and the storage conditions. Temperature, exposure to light and the closure type are often mentioned as the most important storage influences. Especially elevated temperature is known to cause accelerated aging reactions in wine. Refrigerated wine storage cabinets promise to be the best storage option without the need of a wine cellar. They are available in different sizes and fit in every household. However, the influence of vibrations and low-interval temperature fluctuations caused by compressors are parameters that have been neglected in literature. The aim of this thesis was to investigate if vibrations and low-interval temperature fluctuations, which occur in refrigerated wine storage cabinets, have an influence on the post-bottling evolution of a wine. The influence of both parameters was studied separately from each other. The impact of vibration on oxidation and gas uptake from the headspace of a wine bottle into the wine was investigated using a model wine with saturated O2 and different headspace volumes. The study revealed that vibration promotes the dissolution of O2 from the headspace of bottle into the wine resulting in a faster SO2 consumption. Furthermore, it was shown that horizontal bottle position accelerated the O2 uptake significantly. It was concluded that the increased surface size between headspace and wine accelerates the O2 dissolution in wine. Also, bigger headspace volumes caused an accelerated O2 uptake into the wine. An experiment without any headspace volume revealed that the factors vibration and bottle position did not accelerate the O2 consumption in wine. This proves that vibration and bottle position accelerate only the dissolution of O2 in wine, but not the chemical reaction of O2 with wine constituents. The influence of vibration on the volatile profile of wine was investigated using Riesling sparkling and still wines sealed with different closures that were subjected to vibration for six months. Vibration caused no CO2 losses, SO2 and color changes in all wines indicating that vibration caused by compressors has no impact on the gas permeability of the used closures. However, vibration affected the volatile profile of sparkling wine and Riesling still wine sealed with a screw cap. Similar to the model wine study described earlier, it was shown that the equilibrium of volatile substances between the wine and the headspace in a bottle was influenced by vibration. The gas-liquid-equilibrium of some volatile compounds was shifted towards wine, while others were shifted towards headspace. As a result of this, the concentration of volatile compounds in wine is changed. Besides this indirect influence of vibration, the results of this study also suggested that specific degradation and formation reactions of volatile compounds are directly influenced by vibration. These multiple effects of vibration most likely explain why increasing vibration intensities could not be proportionally related to the observed volatile changes. The investigation of different wine styles revealed that the impact of vibration depends strongly on the initial composition of wine, age, and packaging conditions. Especially, headspace volume, closure type and CO2 pressure are likely to influence the equilibrium of volatile substances between the wine and the headspace in a bottle. Another study investigated the impact of low-interval temperature fluctuations on the volatile profile of wine. For this purpose, a Riesling wine was stored for two years under different temperature fluctuation patterns caused by compressors. Additionally, a model wine with nine volatile substances with known concentrations was stored for eight months under the same fluctuation patterns. The low- interval temperature fluctuations were compared to the mean value of the temperature fluctuations. Chemical and sensory analysis revealed that that low-interval temperature fluctuations accelerate wine aging reactions like ester hydrolysis and monoterpene degradation. Even small temperature amplitudes showed a significant impact on wine aging. The observed effect was explained by the Arrhenius equation which states that reaction rates exponentially increase with rising temperatures. A pump effect of air through the closure was initially assumed but not observed in this study. Small deviations in wine temperature, such as those caused by door openings of a refrigerator were found to be negligible. It was concluded that low-interval temperature fluctuations can accelerate wine aging reactions. The amplitude of the temperature fluctuations should be as small as possible during bottle storage of wine. This thesis showed that both parameters, vibration, and low-interval temperature fluctuations, have been proven to influence the evolution of wine during bottle storage. Regarding storage conditions in a refrigerated wine storage cabinet, those parameters should be monitored. Wine connoisseurs should therefore consider good wine cabinets, since some manufacturers emphasize on the importance to minimize vibrations and temperature fluctuations in their devices. The development of technology should be advanced to reduce both vibration and temperature fluctuations in refrigerated wine storage cabinets. Future research should focus on specific wine compounds in model systems and realistic vibration conditions to reveal the relationship between vibration intensities and reaction rates. The impact of low-interval temperature fluctuations on wine compositional changes should be investigated considering horizontal and vertical bottle positions. The calculated acceleration factors due to temperature fluctuations have to be verified by isotherm storage conditions at higher temperatures.     

Impact of closures on wine post-bottling development: a review

Closures have an important influence on wine quality during ageing in bottle. The increasing diversity of wine stoppers and their effect in wine development after bottling has been a subject of intense research. This review focuses on the impact of closures on wine quality during bottle storage. Studies dealing with the effectiveness of closures in protecting wine quality during storage and research conducted in order to determine the impact of closures on wine organoleptic properties are discussed. Several types of closures are described and, more particularly, differences in their permeability leading to variable levels of oxygen in the bottle, the role of closures on the removal and/or addition of undesirable compounds from/to wine are critically reviewed.     

Impact of stopper type on oxygen ingress during wine bottling when using an inert gas cover

Background and Aims: Many articles evaluating oxygen ingress for different wine stoppers have been published. However, none of these have studied the impact of the stopper type on oxygen ingress during the bottling process. This study tested a range of commercially available stopper types on oxygen entry into headspace during bottling.
Methods and Results: Oxygen concentration in the headspace was measured using the Winkler method. Stopper type significantly ( P  < 0.05) affected oxygen introduced into the headspace. Oxygen concentration correlated well with the volume and the overpressure of the headspace and was also strongly influenced by stopper height. Bottles sealed with natural cork had the lowest headspace oxygen concentration (1.31–2.12 mg/L) despite these stoppers having a lower height (38 mm) than the others tested. Non-cork stoppers were associated with higher oxygen concentrations, probably because they generated higher overpressure. Bottles sealed with screw cap and synthetic stoppers had the highest oxygen concentration (3.29–3.82 mg/L) and, in the case of screw caps, this was probably a result of greater headspace volume. Headspace oxygen concentration for the synthetic stoppers and the screw cap was approximately equivalent to the oxygen entrance through natural cork during the first 8–10 months of ageing.
Conclusions: Stopper type can affect oxygen ingress during bottling because of the changes in headspace volume and overpressure.
Significance of the Study: Along with permeability, stopper selection should also consider the effects of stopper type on the amount of oxygen that initially enters the headspace. If the bottler is not equipped with an efficient vacuum and/or inert gas system, the impact of the stopper type on the entry of oxygen is an important consideration.     

The influence of ascorbic acid on the composition, colour and flavour properties of a Riesling and a wooded Chardonnay wine during five years' storage

This paper presents the results from an investigation to assess the development of a Riesling and a wooded Chardonnay wine over five years. The wines were bottled either with or without added ascorbic acid and stored under controlled temperature and humidity conditions. Ascorbic acid addition to wine at bottling had little effect on wine aroma and flavour when the wines in this study had been in bottle for 6 months or less. For both wines, at bottle storage times of 3 years or more, addition of ascorbic acid at bottling resulted in wines with no difference in aroma or less oxidised and/or more fresh fruity aromas, even if all the ascorbic acid had been depleted at the time of assessment, compared to wines without addition of ascorbic acid at bottling. In terms of colour, for the Chardonnay wines, the effect of ascorbic acid addition at bottling assessed between two weeks and two years after bottling suggested that wines without addition were browner and had more overall colour intensity. For the Riesling wines, ascorbic acid addition had no significant effect on brownness and overall colour intensity although the Riesling wines with ascorbic acid were generally higher in yellow colour. The A₄₂₀ measurements, which are widely used to estimate the brown colour of wines, did not always appear to correlate with the brown scores obtained by visual assessment or colour measures by CIELAB when wines with and without ascorbic acid addition were compared together. For both wines, after three and five years storage, the concentration of the antioxidant sulfur dioxide was either little different or else slightly(statistically significantly) higher in wines to which ascorbic acid was added at bottling than those without addition.     

Damage index assessment of dried sultanas by various sorters

A heat test assay has been developed to predict whether red wines will form a lacquer-like pigmented deposit after bottling. Wine samples are held in a dry block-heater at 84°C for 16 h and then cooled at 23°C for 4 h. Under these conditions, unstable wines formed more turbidity than stable wines. Material precipitated and measured as turbidity in the predictive heat test had a chemical composition similar to that of bottle deposits. The degree of turbidity produced in the predictive assay was related to the amount of bottle deposit formed in a long-term storage trial. By varying the headspace volume and the amount of one of several antioxidants in the wine, the assay confirmed that formation of the bottle deposit is an oxidative process.     

橡木桶陈酿技术对猕猴桃酒品质的影响

为了提高猕猴桃果酒的品质,本文研究了采用橡木桶进行陈酿过程对猕猴桃果酒理化指标和感官评价的影响,具体包括溶解氧、电导率、色度和色调等物理指标,游离二氧化硫、总酚、高级醇等化学指标和感官评价得分。结果显示:随着猕猴桃果酒陈酿时间的延长,电导率、色度、色调等理化指标均呈现了明显的上升趋势,且逐渐趋于平衡,分别为电导率2.76 mS/cm,色度0.375,色调4.05;而溶解氧、游离二氧化硫、总酚等理化指标均呈现了明显的下降趋势,并逐渐趋于稳定,溶解氧0.72 mg/L,游离二氧化硫27.87mg/L,总酚332mg/L;随着陈酿时间延长,异丁醇、异戊醇和高级醇总含量都呈现下降趋势;经过橡木桶陈酿后的猕猴桃果酒其感官得分为97.68,明显高于感官得分为79.84的玻璃瓶贮藏的猕猴桃果酒样品。因此,贮藏过程中猕猴桃酒理化和感官评价变化与溶解氧含量及变化、橡木桶结构和成分有关。     

平静葡萄酒泡沫研究

以平静红葡萄酒为研究对象，采用气相色谱等分析方法研究了该酒的泡沫成分，研究结果表明：某泡沫挂杯严重的原装葡萄酒顶空气样中ＣＯ２含量占５７％，其它成分主要为Ｎ２，说明平静葡萄酒泡沫的主要成分为ＣＯ２。本文对泡沫产生的原因和去除方法进行了探讨。