Exclusion of sunlight from Shiraz grapes alters wine colour, tannin and sensory properties

The aim of this study was to determine how changes in grape composition brought about by artificial shading (sunlight exclusion) influence wine properties including colour, flavonoid composition and sensory attributes. Prior to flowering, bunches of Shiraz grapes were enclosed in boxes designed to eliminate light without altering bunch temperature and humidity. This artificial bunch shading had little effect on berry ripening and accumulation of sugar but at harvest the shaded bunches had smaller berries and higher seed weight, juice pH and titratable acidity. The amount of anthocyanins in the fruit was not changed significantly but anthocyanin composition in the shaded berries was shifted towards dioxygenated anthocyanins (the glucosides of cyanidin and peonidin derivatives). Shaded fruit had increased seed tannins and decreased skin tannins but the largest relative change in flavonoids was a marked decrease in flavonols in the shaded fruit, similar to previous studies. Wines made from shaded fruit had lower wine colour density, total phenolics, anthocyanins and tannins when the wine was bottled and after ageing for up to three years. Analysis of potential flavour compounds following acid hydrolysis indicated that the wines made from shaded fruit had decreased levels of glycosides of β-damascenone and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN). Sensory analysis of the wines indicated no significant difference in aroma attributes but the wines made from shaded fruit were rated lower for astringency, fruit flavour and flavour persistence in-mouth sensory attributes. The results indicate that extreme shading of Shiraz fruit can decrease wine colour, anthocyanins and tannins as well as altering sensory attributes.     

不同工艺处理对野生猕猴桃酒品质的影响

分别对野生猕猴桃进行清汁、混汁和带皮发酵处理,采用顶空固相微萃取技术对不同酿造工艺野生猕猴桃酒的香气进行富集,用气相色谱-质谱联用技术对其进行定性定量分析,结合酒的基本理化指标和感官评价比较不同工艺处理野生猕猴桃酒的品质。结果表明：混汁发酵和带皮发酵可降低猕猴桃酒的总酸及挥发酸质量浓度,提高pH值,减少VC损失;带皮发酵的香气物质总量显著高于清汁和混汁发酵（P＜0.05）,且酒中的酯类、萜烯类、酮类物质质量浓度相对较高,但酸类物质质量浓度显著降低（P＜0.05）;不同工艺处理酒中特征香气有所差异,其感官香气也各具特色;带皮发酵酒的香气评分较高,猕猴桃品质特征香气突出;且在口感质量、口感浓度、口感纯正度、香气质量、香气浓度、香气纯正度及整体平衡性方面均优于清汁发酵和混汁发酵。因此,带皮发酵工艺可一定程度提高野生猕猴桃酒的品质。     

Inhibition and inactivation evaluation of exogenous glycosidases in wines using p‐nitrophenylglycosides

BACKGROUND: Glycosidases are often used to improve the aroma of wines via hydrolysis of glycosidic precursors. The aim of this work was to develop a method to test activity and stability of these enzymes in wine environments using p‐nitrophenylglycosides, avoiding interference by colored substances. RESULTS: The proposed procedure for determination of glycosidase activity in wines involves quantification of the hydrolysis product p‐nitrophenol by HPLC. The method was applied to compare the inhibition of some commercial glycosidases by red and white wines. It was found that inhibition of a β‐D ‐glucosidase by ethanol, glucose and gluconolactone was smaller than that produced by wine. This enzyme was also inhibited by wine fractions rich in phenolic compounds and glycosides. When glycoside fractions were first hydrolyzed, their inhibition was strongly reduced. The stability of glycosidases in red wines was tested, showing a destabilizing effect of β‐glucosidases that was stronger than in white wine. CONCLUSION: The method developed allows measurement of glycosidase activity on p‐nitrophenylglycosides in the presence of colored wine compounds. Comparison of relative glycosidase activity in wines to that in buffer solution under the same conditions can assist in the selection of appropriate aroma‐enhancing enzymes. Copyright © 2009 Society of Chemical Industry     

Release of wine monoterpenes from natural precursors by glycosidases from Oenococcus oeni

It is now well established that wine-related lactic acid bacteria (LAB), especially Oenococcus oeni, possess glycosidase activities that positively contribute to wine aroma through the hydrolysis of grape-derived aroma precursors. In our recent studies, we have identified and characterised several LAB glycosidases with potential in these terms. Here, we report that both a glucosidase and an arabinosidase from O. oeni can release high amounts of monoterpenes from natural substrates under optimal conditions, indicating that these intracellular enzymes might play a significant role in the hydrolysis of aroma precursors during malolactic fermentation. The enzymes from O. oeni exhibited broad substrate specificities (release of both primary/tertiary terpene alcohols) and were even active in grape juice. Further, a sensory panel clearly preferred enzyme-treated Riesling wines over the controls and affirmed that the glycosidases from O. oeni could improve the typical Riesling aroma.     

酿酒和鲜食葡萄酿造起泡葡萄酒品质差异研究

选用陕西地区的鲜食葡萄品种户太八号、夏黑和酿酒品种爱格丽、嘉年华、玫瑰香为原料,酿制小容器起泡葡萄酒,并对不同品种葡萄酿造的起泡葡萄酒进行酚类物质、香气物质及感官指标进行定量描述分析（QDA）比较。结果表明：不同品种葡萄果实及起泡葡萄酒总酚含量存在显著差异（P＜0.05）,鲜食葡萄品种的总酚含量高于酿酒葡萄品种,夏黑葡萄果实中的总酚含量最高,为（97.95±2.93） mg/g,5种起泡葡萄酒的基本指标均符合国家标准,其中酿酒品种中嘉年华及鲜食品种里户太八号起泡葡萄酒的酚类物质含量较高;5种起泡葡萄酒共检测出香气物质50种,其中玫瑰香起泡葡萄酒香气物质种类最多（33种）;QDA分析结果表明,爱格丽及夏黑起泡葡萄酒感官品质较佳,分别得分75.99分和81.80分。     

Wine produced by immobilized cells on dried raisin berries in sensory evaluation comparison with commercial products

Comparative sensory evaluation of wines produced by immobilized cells of Uvaferme 299 on dried raisin berries and free cells using the Saint Denis grape variety and of commercial Greek products (‘Biblia Chora’ rosé wine produced from the Syrah grape variety, ‘Palivos’ and ‘Strofilia’ rosé wines both produced from the Agiorgitiko grape variety) was carried out. Sensory evaluation was conducted twice by 11 tasters previously trained and a method for panel validation was proposed. Subsequently, the wines were evaluated for their aroma intension, aroma complexity, aroma elegance and overall quality. Duncan's multiple range test clearly showed that there were statistically significant differences between wines produced using different grape varieties and fermentation conditions. Linear regression analysis of the results was performed in order to investigate which sensory parameter had a significant effect on the overall quality and it revealed that only aroma elegance affected significantly the overall quality. Wine produced by immobilized cells scored a statistically higher value for its overall quality than the wine produced by free cells. Finally, discriminant sensory evaluation revealed a gooseberry, cherry, mint aroma for ‘Biblia Chora’ wine and a citrus, rose aroma for ‘Strofilia’ and ‘Palivos’ wines. Wines produced using immobilized and free cells were characterized by a fruity, banana‐like aroma, and a herbaceous note was predominant. Copyright © 2005 Society of Chemical Industry     

枸杞牛乳肽酒制备工艺优化及其抗氧化性分析

为克服传统白酒功能性、营养性不足的缺陷,以脱脂牛乳和枸杞为材料,采用对比及正交试验,对乳蛋白酶解条件、枸杞牛乳肽酒的制备工艺和抗氧化功能进行了研究。结果表明:1)胰蛋白酶是水解牛乳蛋白的最佳蛋白酶;2)胰蛋白酶的最佳酶解条件是在pH 7.0、温度40℃、加酶量4 500 U/g的条件下酶解120 min;3)枸杞牛乳肽酒的最佳发酵工艺:以牛乳蛋白酶解液为载体,添加体积分数14%枸杞汁、7.5%的活化酵母菌液,28℃发酵9 d。制备的枸杞牛乳肽酒具有较高的体外抗氧化活性,且香味协调,口感良好,其感官指标和理化指标都符合并高于国家发酵型甜奶酒的标准。     

Berry sensory attributes correlate with compositional changes under different viticultural management of Semillon (Vitis vinifera L.)

A study was performed on Vitis vinifera L. (cv. Semillon) to determine changes in berry sensory attributes and composition when vineyard management practices; leaf removal and bunch thinning are applied. Leaf removal increased skin and pulp acidity sensory attributes which corresponded to a decrease in juice pH, malic acid and potassium. Pulp grassiness also decreased with leaf removal, whereas, skin and pulp grape and citrus flavour intensity increased. Bunch thinning increased pH, malic acid and potassium but this was not related to significant changes in berry sensory attributes; however pulp grassiness flavour did increase. Inductively coupled plasma optical emission also revealed changes in elemental juice levels under different management practices. PCA analysis revealed strong correlations between sensory attributes and berry composition. Grape quality can be manipulated by management practices and berry composition and berry sensory analysis combined may be a useful tool for making management and harvest decisions to achieve certain wine styles.     

Enhancement of volatile aromatic compounds in black raspberry wines via enzymatic treatment

Robus coreanus Miquel is widely used in the production of Korean black raspberry (KBR) wine owing to its health benefits and commercial value. The effects of three different commercially available glycosidase enzymes on the volatile compounds in KBR wines were investigated with large‐scale fermentation to develop a high‐flavour‐quality wine. Volatile aroma compounds from the wines were analysed using headspace‐solid phase micro‐extraction‐gas chromatography–mass spectrometry (HS‐SPME‐GC–MS) and sensory evaluations were performed to evaluate the flavour characteristics. KBR wines treated with commercial enzymes yielded high concentrations of terpenes and esters compared with the control wine because the odourless non‐volatile glycosides in KBR wines were converted to their corresponding free forms by the enzymes. HS‐SPME‐GC–MS‐SIM analysis showed that the primary monoterpene compounds in KBR wines treated by the enzymes were myrtenol, linalool, citronellol and a significant quantity of compounds such as 2‐phenyl ethanol and ethyl benzoate, which contributed to the flavour of KBR wine, as determined by GC‐FID. KBR wines treated with the enzymes exhibited different sensory characteristics from the control wine owing to higher intensity of floral and fruity aromas. KBR wine treated with CYTOLASE PCL5 on a large scale exhibited the highest sensory preference. Copyright © 2017 The Institute of Brewing & Distilling     

Enhancement of Aroma in White Wines Using a β-Glucosidase Preparation From Debaryomyces pseudopolymorphus (A-77)

The liberation of aromas in young wines is presently one of the most interesting subjects in enology. The hydrolysis of the glycosidic compounds (aroma precursors) of grape varieties from Castilla-La Mancha (Spain) has been studied, using an enzymatic preparation from Debaryomyces pseudopolymorphus (A-77) with high β-glucosidase activity. This preparation was added to the wines and its effect was observed at 6 and 12 days of incubation. Enzymatic activity was studied quantifying both the precursors that were not hydrolysed and those that liberated volatile compounds by gas chromatography/mass spectrometry.

The results were compared with a control wine (without enzyme) and also with a wine treated with a commercial fungal enzyme preparation specifically recommended for the liberation of aromas in wines. It was observed that the enzymatic extracts from D. pseudopolymorphus were adequate and that they could compete with the commercial preparations since the volatiles liberated were more controlled and it took less time to get the same results. To complete the study, the results obtained in regards to the liberation of volatiles were corroborated by sensory analysis.     

Impact of Multicolored Asian Lady Beetles on the Sensory Properties of Concord and Niagara Grape Juice

ABSTRACT: The presence of Multicolored Asian Lady Beetles (MALB) in grape juice is increasingly problematic. The overall objective of this study was to determine the specific sensory impacts of MALB on Concord and Niagara grape juice. The aroma threshold for MALB-taint in both juices was determined and expressed as the best estimate threshold (BET). The aroma BET for MALB-taint in Concord grape juice was 1.8 and 0.65 MALB/L Niagara grape juice. The specific sensory attributes of the grape juices influenced by the presence of MALB were then described. In Concord grape juice, trained panelists (n = 9) found significant increases in vegetal aroma and earthy flavor as MALB concentration increased from 0.45 to 7.2 MALB/L. In Niagara grape juice, with increasing MALB concentration, trained panelists (n = 8) indicated significant decreases in honey and sweetness with corresponding increases in sourness, astringency, and vegetal and earthy aromas and flavors (P < 0.05). For both aroma and flavor, consumer rejection studies were performed using paired preference comparisons of control juice to MALB-tainted grape juice. For Concord grape juice, consumers (n = 60) rejected the aroma of MALB-tainted juice at 1.8 MALB/L and the taste/flavor of the MALB-tainted juice at 3.6 MALB/L. For Niagara juice, consumers rejected the aroma of the juice at 3.6 MALB/L. This study demonstrated the presence of MALB negatively impacts the sensory properties of Concord and Niagara grape juice. Grape juice processors may use this research for quality control measures and for establishing tolerance limits. Practical Application: The Multicolored Asian Ladybeetle (MALB), initially used for biocontrol, has been shown in previous literature to impact the sensory properties of wines. The presence of MALB in grape juice is now becoming problematic; however, there is little research describing the specific sensory impacts of MALB on grape juice. This study examined the sensory impact of MALB on both Concord and Niagara grape juice. While the threshold and trained panel evaluations from this study provide valuable sensory profile information, grape juice processors may be particularly interested in the consumer rejection of MALB-tainted grape juice as they can use this research for quality control measures and for establishing tolerance limits.     

低温处理葡萄对爱格丽干白葡萄酒香气成分的影响

目的：以不同温度处理爱格丽葡萄原料,寻找增加爱格丽干白葡萄酒香气的最适温度。方法：以白色酿酒葡萄品种爱格丽为原料,16 ℃处理为对照,分别在4、－8、－20、－32 ℃条件下进行低温处理,采用小容器酿酒规范酿制葡萄酒并测定葡萄酒的理化指标,搅拌棒吸附萃取（stir bar sorptive extraction,SBSE）提取葡萄酒中的香气成分,再通过热脱附-气相色谱-质谱联用仪来定性和定量分析葡萄酒的香气成分,用SPSS 19.0软件进行香气成分的主成分分析（principal component analysis,PCA）,8 名经过培训的感官品尝小组成员对酒样进行感官评价。结果：低温处理能促使葡萄酒中香气成分种类的增加和含量的提高。结论：－8、－20 ℃低温处理葡萄可以显著提高爱格丽干白葡萄酒的香气质量,可在一定程度上使葡萄酒的香气更加浓郁。     

Gas Chromatographic headspace analysis of Chardonnay and Semillon wines after thermal processing

Volatile compounds of Chardonnay and Semillon wines were analysed using a dynamic headspace method based on selective capillary column trapping and gas chromatography with another column. The effect of thermal treatment on the volatile composition of the wines was studied. Some grape derived norisoprenoid compounds, important to the aroma of aged wine, were formed at 45°C by hydrolysis from the glycosidic precursors. The heat treatment increased the proportion of 1,1,6-Trimethy1-1,2-dihydronaphthalene (TDN) and vitispirane in Chardonnay and Semillon wines. Headspace volatiles of model wines, to which the glycosidic fraction of Chardonnay and Semillon juices was added, were also analysed.

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Gaschromatographische Kopfraum-Analyse der erhitzten Chardonnay- und Semillon-Weine

Zusammenfassung Flüchtige Verbindungen der Weine Chardonnay und Semillon wurden mittels der dynamischen Kopfraum-Methode untersucht. Die flüchtigen Substanzen wurden selektiv mit einer Capillarsäule abgefangen und gaschromatographisch mit einer anderen Säule behandelt. Der Effekt einer Hitzebehandlung auf die Zusammensetzung der flüchtigen Verbindungen der Weine wurde untersucht. Durch Hydrolyse bei 45 °C wurden aus glykosidischen Vorstufen einige Norisoprenoid-Verbindung gebildet, die für das Aroma länger gelagerter Weine wichtig sind. Durch die Hitzebehandlung wurden die Anteile von 1,1,6-Trimethyl-1,2-dihydronaphtalen (TDN) und Vitispirane der Chardonnay- und Semillon-Weine erhöht. Zusätzlich wurden die flüchtigen Verbindungen solcher Referenzweine analysiert, denen die glykosidische Fraktion der Chardonnay- und Semillon-Traubensäfte zugesetzt worden war.

     

Enhancement of Aroma in White Wines Using a β-Glucosidase Preparation From Debaryomyces pseudopolymorphus (A-77)

The liberation of aromas in young wines is presently one of the most interesting subjects in enology. The hydrolysis of the glycosidic compounds (aroma precursors) of grape varieties from Castilla-La Mancha (Spain) has been studied, using an enzymatic preparation from Debaryomyces pseudopolymorphus (A-77) with high β-glucosidase activity. This preparation was added to the wines and its effect was observed at 6 and 12 days of incubation. Enzymatic activity was studied quantifying both the precursors that were not hydrolysed and those that liberated volatile compounds by gas chromatography/mass spectrometry.

The results were compared with a control wine (without enzyme) and also with a wine treated with a commercial fungal enzyme preparation specifically recommended for the liberation of aromas in wines. It was observed that the enzymatic extracts from D. pseudopolymorphus were adequate and that they could compete with the commercial preparations since the volatiles liberated were more controlled and it took less time to get the same results. To complete the study, the results obtained in regards to the liberation of volatiles were corroborated by sensory analysis.     

适宜‘法国野’葡萄的葡萄酒生产类型探究

为挖掘云南地方酿酒葡萄品种‘法国野’的酿酒潜力,筛选适合该品种的葡萄酒生产类型和基本工艺。采用4种工艺酿制2个类型葡萄酒:浸渍发酵法(maceration-fermentation,MF)酿制干红葡萄酒、冷浸渍+放血法(cold pre-fermentation maceration&saignée,CMS)酿制桃红葡萄酒、冷浸渍+放血+浸渍发酵法(cold pre-fermentation maceration,saignée and maceration-fermentation,CMS-MF)酿制干红葡萄酒,直接压榨法(direct press,DP)酿制桃红葡萄酒,其中2款干红葡萄酒均进行苹果酸-乳酸发酵(malolactic fermentation,MLF)。陈酿3个月后,对4款葡萄酒进行理化指标分析和感官评价。结果表明:与DP和MF相比,CMS和CMS-MF可分别显著提高桃红和干红葡萄酒的单宁、花色苷、总浸出物含量及色度;且CMS和DP桃红葡萄酒的香气、口感和总评得分均显著高于MF和CMS-MF干红葡萄酒,但同类型葡萄酒间的感官质量并无显著差异(P <0.0...     

Effect of Maceration Time on Free and Bound Volatiles of Red Wines from cv. Karaoğlan (Vitis vinifera L.) Grapes Grown in Arapgir,Turkey

Skin maceration is an essential winemaking technique that affects sensory properties and aroma of red wines. The aim of this study was to investigate aroma profiles of red wines made from cv. Karao?lan, a grape variety grown in Arapgir (Malatya, Turkey) and the effect of maceration time (5, 10, and 15 d) on free and bound aroma compounds and sensory properties. Three maceration times were applied in durations of 5, 10, and 15 d. Free and glycosidically bound aroma compounds were analyzed using gas chromatography‐mass spectrometry (GC‐MS) in Karao?lan wines, and the effect of different maceration times on aroma composition were evaluated. Results indicate that extended maceration time significantly influenced the aroma composition of wines both qualitatively and quantitatively. A total of 59 free and 22 bound aroma compounds were identified in the final wines. The maximum of free aroma content was achieved with 5 d of maceration, while 15 d of maceration gave the highest amount of glycosidically bound aroma compounds. From sensorial point of view, the wine produced with 10 d of maceration had the best panel score compared to wines with 5 and 15 d of maceration. This is the first study referring to the composition of aroma compounds of red wines made from cv. Karao?lan. It was concluded that this cultivar resulted in a good quality wine in terms of bound and free aroma compounds. This information of vinification practices that influence the chemical properties of wine is useful for grape growers and winemakers.