Influence of the yeast strain on Monastrell wine colour

Two commercial yeast strains were assayed during the winemaking process of Monastrell grapes to determine their influence on colour and phenolic composition of the resulting wines during alcoholic fermentation and maturation. The results showed that in 2002, the wines did not present great differences but in 2003 higher colour intensity and phenolic compounds content were detected when one of the commercial strains was used. A discriminant statistical analysis clearly showed that different yeasts led to different wines as regard their chromatic characteristics.Industrial relevanceThe importance of yeast in winemaking is extensively known since they are responsible for the transformation of sugars into ethanol and for the formation of the most significant aroma compounds in wines. However, they may also participate in wine colour and this role is usually not taken into account in the wine industry. The choice of a yeast strain is an important factor since these microorganisms have the capacity to retain or adsorb phenolic compounds and, on the other hand, yeast may contribute to stabilizing wine colour, as a result of participating in the formation of vitisins during fermentation or liberating mannoproteins that have the capacity to bind to anthocyanins and tannins, protecting them from precipitation. Two commercial yeast strains were assayed during the winemaking process of Monastrell grapes to determine their influence on colour and phenolic composition of the resulting wines during alcoholic fermentation and maturation. The results showed that higher colour intensity and phenolic compounds content were detected when one of the commercial strains was used, both during fermentation and wine aging, and may be used as a tool during winemaking for obtaining stable and highly coloured wines.     

Effect of cofermentation of grape varieties on aroma profiles of la mancha red wines

The effect of winemaking using blends of red grape varieties cultivated in La Mancha region (Spain) on the aroma profile of wines was researched by chemical characterization. Free and glycosidically bound aroma compounds were isolated by solid phase extraction using dichloromethane and ethyl acetate, respectively, as solvents in elution and then analyzed by gas chromatography-mass spectrometry. Free and bound volatile compounds were analyzed in Cencibel, Bobal, and Moravia Agria monovarietal wines, and in 3 wines obtained with the blending of grapes: Cencibel (50%) + Bobal (50%); Cencibel (50%) + Moravía Agria (50%); Cencibel (33%) + Bobal (33%) + Moravía Agria (33%). Aroma compounds were studied in terms of odor activity values (OAVs). Ninety free aroma compounds and sixty-five bound aroma compounds were identified and quantified. The odor activity values for the different compounds were classified into 7 odorant series. The fruity and sweet series contributed most strongly to the aroma profile of all wines, independently of the winemaking technique used. In general, co-winemaking wines present a more complex chemical profile than monovarietal wines. Practical Application: Some grape varieties could benefit from this process with the presence of other varieties that might have an excess of aroma compounds. In this study, the wines were elaborated by blending different grape varieties together; this process implies co-maceration and co-fermentation steps. The co-winemaking technique could benefit from additional molecules provided by the other varieties, which results in a more complex formation than in the case of monovarietal wines. This technique provides a viable alternative to traditional winemaking methods for improving and enhancing the sensory profile of elaborated wines.     

Methoxypyrazine Analysis and Influence of Viticultural and Enological Procedures on their Levels in Grapes,Musts, and Wines

This review discusses the factors that affect the concentrations of methoxypyrazines (MPs) and the techniques used to analyze MPs in grapes, musts, and wines. MPs are commonly studied pyrazines in food science due to their contribution of aroma and flavor to numerous vegetables such as peas and asparagus. They are described as highly odorous compounds with a very low olfactory threshold. The grape varietals that exhibit green or herbaceous aromas that are characteristic of MPs are predominantly Vitis vinifera cv. Cabernet Sauvignon and Sauvignon Blanc, but include others. The most extensively studied MPs include 3-isobutyl-2-methoxypyrazine, 3-isopropyl-2-methoxypyrazine, and 3-sec-butyl-2-methoxypyrazine. It outlines the significance of methoxypyrazines in grapes, musts, and wines in terms of the concentrations that are capable of contributing their sensory characteristics to wines. This review discusses methods for analyzing MPs including gas chromatography-mass spectroscopy (one or two dimension) and high-performance liquid chromatography, the appropriate extraction techniques, and the efficacy of these methods. Additionally, this review explores factors that affect pyrazine content of grapes, must, and wines, such as the effects of different viticultural practices, effects of light exposure and grape maturation, climate, soil, the multi-colored Asian lady beetle and the effects of different vinification processes.     

Impact of phytosanitary treatments with fungicides (cyazofamid, famoxadone, mandipropamid and valifenalate) on aroma compounds of Godello white wines

Cyazofamid, famoxadone, mandipropamid and valifenalate, four new fungicides for controlling downy mildew in vine, were applied to an experimental vineyard producing Vitis vinifera white grapes of the Godello variety. Following harvest, the grapes were subjected to single vinification runs. The odour activity values (OAVs) for the Godello white wines obtained were estimated with a view to assessing potential alterations of their aroma composition by effect of the phytosanitary treatments. Several fatty acids, their esters and acetates were formed during the winemaking process in high levels and could be expected to strongly influence the aroma of the wines by introducing floral, fruity and spicy nuances. The concentrations of six compounds (2-phenylethyl acetate, ethyl butanoate, ethyl octanoate, 4-vinylguaiacol, 3-methylbutanoic acid and methionol) were found to suffice with a view to discriminating between wines from grapes treated with fungicides under Critical Agricultural Practices (CAP) and under Good Agricultural Practices (GAP).     

人工贵腐玫瑰蜜葡萄酒的酿造及香气成分分析

以玫瑰蜜葡萄为原料,通过人工接种贵腐菌的方法来获得贵腐葡萄,评价人工酿造贵腐玫瑰蜜葡萄酒技术的可行性。本研究在感染灰霉病的夏黑葡萄果实上分离灰葡萄孢(Botrytis cinerea)菌株,通过形态学和分子鉴定,确定分离菌株为灰葡萄孢(B. cinerea)。然后用喷洒孢子悬浮液的方法对玫瑰蜜葡萄进行人工接种,获得贵腐葡萄,酿造贵腐葡萄酒。用顶空固相微萃取气质联用(HS-SPME-GC-MS)分析人工贵腐酒的香气成分,通过与对照相比,人工贵腐酒一共检测到了42种香气物质,对照检测到了29种。通过分析发现玫瑰蜜人工贵腐酒含有更多种类的酯类和醛酮类化合物,具有典型的香气成分,更加丰富和复杂的香气特征。     

Carbonyl compounds in different stages of vinification and exposure risk assessment through Merlot wine consumption

ABSTRACT

The objective of this research was to estimate for the first time the transformations that the free form of some target carbonyl compounds may undergo during winemaking and assess the exposure risk to these compounds through the consumption of the Merlot commercial wines under study. Acrolein and furfural were found in grapes and the respective wines, although levels were observed to decline throughout the winemaking process. Formaldehyde was found in all stages of wine production in levels lower than the limit of quantification of the method and ethyl carbamate was not found in samples. Acetaldehyde seems to be a precursor of acetoin and 2,3-butanediol, since the levels of this aldehyde decreased along winemaking and the formation of the ester and alcohol was verified. Furfural levels decreased, while the occurrence of furan-containing compounds increased during winemaking. The formation of acetaldehyde during alcoholic fermentation and the potential environmental contamination of grapes with acrolein and furfural are considered as the critical points related to the presence of toxic carbonyl compounds in the wine. Acrolein was found in the samples under study in sufficient quantities to present risk to human health, while other potentially toxic carbonyl compounds did not result in risk. This study indicated for the first time the presence of acrolein in grapes suggesting that environmental pollution can play an important role in the levels of this aldehyde detected in wines. Reduction of the emission of this aldehyde to the environment may be achieved by replacing wood burning by another heat source in fireplaces or wood stones, and abandoning the practice of burning garbage and vegetation.     

Effects of Different β‐D‐Glycosidases on Bound Aroma Compounds in Muscat Grape Determined by HS‐SPME and GC‐MS

Important “floral” aromas naturally occur in grapes predominantly as flavourless glycoconjugate precursors. Since these aroma compounds can be released by hydrolysis, different glycosidase enzymes can potentially contribute different aromas to wines. In this paper, we first established a procedure for profiling the free and bound volatile compounds in grape using GC‐MS combined with headspace solid‐phase microextraction (HS‐SPME). Comparison of the free and bound aroma compounds revealed that non‐volatile glycosides, known as aroma precursors, occur in high concentrations in musts. Among all compounds identified, 11 were fully quantified according to established standard calibration curves, while others were semi‐quantified. Using three different glycosidase enzymes, a total of 38 bound volatile compounds were identified in Muscat grape, including terpenes, higher alcohols, C‐6 compounds, and phenols, among others. The different enzymes had significant effects on the varietal aroma. Principal component analysis indicated that the characteristic aroma hydrolyzed by the commercial enzyme AR2000 was clearly different from that produced by other enzymes.     

GC-MS法研究玫瑰香葡萄酒中的香气成分

以天津茶淀玫瑰香葡萄为原料,用不同的酵母菌来酿造玫瑰香葡萄酒.采用固相微萃取结合气质色谱的方法对葡萄酒中的挥发性香气物质进行榆测.共识别出60种化合物,主要香气成分为醇类、酯类、酸类、萜烯类物质.不同酵母发酵葡萄酒中的香气成分种类区别不大,而含量有差别.尤其是2种酵母产生的醇类物质的总量差别较大,而二者的产酯能力几乎相同.     

EFFECTS OF DIFFERENT MACERATION TIMES AND PECTOLYTIC ENZYME ADDITION ON THE ANTHOCYANIN COMPOSITION OF VITIS VINIFERA CV. KALECIK KARASI WINES

Kalecik karasi is an important red grape cultivar for winemaking in Turkey. The effect of three different maceration times (3, 6 and 12 days) and addition of pectolytic enzyme (2 and 4 g/hL) on the anthocyanin and chemical composition of Kalecik karasi wines were studied. High performance liquid chromatography-mass spectrometry coupled with diode array detection was used for analysis. Fourteen anthocyanin compounds were detected in wines. Major anthocyanins in all wines are malvidin-3-glucoside and its acylated esters. The results showed that increasing maceration time, especially with addition of enzymes, gives significant increases in anthocyanin contents. Moreover, the wines treated with enzymes had higher values in total phenolics, tannins, and color intensity than the control wines.

PRACTICAL APPLICATIONS

Anthocyanins are the most important polyphenols in red grapes and red wines with potential health benefits. Therefore, the first analysis of the anthocyanins contents of wine obtained from important turkish cv. Kalecik karasi using liquid-chromatography-mass spectrometry and the influence of different maceration times and addition of pectolytic enzyme on these important phenolic compounds are of interest for scientific literature, the wine industry as well as for the wine consumer.     

Changes of the sensorial attributes of white wines with the application of new anti-mildew fungicides under critical agricultural practices

Although the winemaking process could allow the dissipation of residues of fungicides applied under critical agricultural practices (CAP), their residual levels could alter the biosynthesis of volatile compounds. The purpose of this work is to look for changes in the aroma profile of those wines in comparison with wines treated under good agricultural practices (GAP). Four new fungicides (mandipropamid, valifenalate, cyazofamid and famoxadone), used to control downy mildew (Plasmoparaviticola), were applied under CAP in an experimental vineyard producing white grapes (Vitisvinifera) of Godello var. Once grapes were harvested, single vinifications were performed. Possible modifications of sensorial properties of wines were evaluated by a trained sensorial testing panel constituted of 7 experts. The fungicide residues induced an increment of typical fermentative odours associated with esters in treated wines. The critically treated wine was moved to a sweeter balance with a ripe fruit taste, associated with higher viscosity and greater cloudiness.     

Oenological potential of wines produced from disease-resistant grape cultivars

Within the EU, changes in policy and public sentiment have made it more urgent to consider the adoption of sustainable agricultural practices. Consequently, one of the EU’s goals is to reduce pesticide use by 50 per cent by 2030, including in viticulture. One of the proposed approaches is to expand the use of disease resistant hybrid grape-cultivars (DRHGC), such as ‘PIWI’ grapes (German, Pilzwiderstandsfähige Rebsorten), and to introduce new DRHGCs. However, the characteristics of DRHGCs are different from those of Vitis vinifera, which makes it necessary to take measures and make changes in winemaking technology to maintain high wine quality. This paper examines the chemistry of wines made from DRHGC and discusses their impact on aroma and flavor profiles. It also reviews the main winemaking practices suggested to produce high-quality wines from DRHGCs. The chemistry of DRHGCs is different to wine produced from V. vinifera, which can lead to both challenges during winemaking and unusual flavor profiles. Although newer DRHGCs have been bred to avoid unexpected flavors, many DRHGCs are still rich in proteins and polysaccharides. This can make tannin extraction difficult and produce wines with little astringency. In addition to this, new or alternative winemaking techniques such as thermovinification and the use of alternative yeast strains (non-Saccharomyces) can be used to produce wines from DRHGCs that are acceptable to consumers.     

FLAVOR AND AROMA ATTRIBUTES OF RIESLING WINES PRODUCED BY FREEZE CONCENTRATION AND MICROWAVE VACUUM DEHYDRATION

This article describes the production of sweet dessert wines produced using late‐harvest freeze concentration, wine produced from fresh grapes frozen using refrigeration and wine produced from grapes partially dried using microwave vacuum dehydration. The objective was to compare the aroma and flavor attributes of the wines to determine the effect of each method of juice concentration. The replicated wine samples were evaluated by 12 experienced judges, and the wines were analyzed using solid‐phase microextraction. The microextraction detected 28 compounds; however, levels of concentration of these compounds were below published aroma thresholds. Although all the wines were judged as acceptable sweet dessert wines, the judges detected significant differences. The wine made from the dehydrated grapes exhibited lower fresh fruit aroma, higher fusel oils and oxidation, and flavor notes including citrus/grapefruit and acidity were lower.     

Applications of an oak extract on Petit Verdot grapevines. Influence on grape and wine volatile compounds

Petit Verdot vineyards were treated at veraison with a commercial aqueous French oak extract in order to determine if the extract’s volatile components can be transferred to grapes and then to wines. Three different formulations (25% (one application), 25% (four applications) and 100%) were tested, together with an eugenol and guaiacol standard solution to better follow their behaviour. The volatile compounds of treated grapes and their wines after alcoholic and malolactic fermentation and after 8 months were analysed by stir bar sorptive extraction and gas chromatography mass spectrometry (SBSE-GC–MS). The results showed that the grapes stored the volatile compounds mainly as non-volatile precursors, and some of these were released after winemaking. In the case of wines, it was possible to distinguish the control versus the ones from vineyard treatments. The different oak extract applications were evident only after alcoholic fermentation sampling, making it very interesting for young wines.     

Effect of the winemaking technique on phenolic composition and chromatic characteristics in young red wines

The effect of six winemaking techniques (traditional, prefermentative maceration, delestage, Ganimede fermentation system, enzymes and tannins addition, or oak chip addition during alcoholic fermentation) on phenolic composition and chromatic characteristics of young red wines, elaborated from Mencía grapes grown in Galicia (northwestern Spain), was studied. The evolution of phenolic compounds from grapes to bottling and its influence on CIELab parameters were investigated. After bottling, 26 phenolic compounds were determined by high-performance liquid chromatography (HPLC), and their influence on colour stability for ageing was evaluated. Principal component analysis allowed the differentiation of the winemaking techniques studied on the base of phenolic composition, which is correlated with polymerization grade of anthocyanins. This paper can contribute to improve the knowledge about the importance of selecting the winemaking technique to elaborate high-quality young red wines and to evaluate their ability for ageing. So, the addition of enzymes and tannins seems to be the most adequate winemaking technique to elaborate red wines for ageing as it results in the formation of major number of pigmented polymers that are stable over time. Nevertheless, the prefermentative maceration, Ganimede autowinemaker and the addition of oak chips can be used for the elaboration of young red wines.     

Sensory and chemical characterisation of the aroma of Prieto Picudo rosé wines: The differential role of autochthonous yeast strains on aroma profiles

This study evaluates the specific impact of isolated yeast strains on the aromatic profile of fermented musts from Prieto Picudo, an autochthonous Castilla y León (Spain) red grape variety with an increasing demand in the local marketplace. For this purpose, the aroma profiles of wines elaborated from Prieto Picudo grapes have been studied by sensory analysis, gas chromatography–olfactometry (GC–O) and gas chromatography–mass spectrometry (GC–MS), with the aim of determining the potential of each strain to generate distinctive varietal and fermentation-derived aromatic compounds. The results have shown that the yeast strain exerts a critical influence on the levels of some fermentative (linear and branched ethyl esters, fatty acids, ethyl phenylacetate) and varietal compounds (4-mercapto-4-methyl-2-pentanone, 3-mercaptohexylacetate, β-damascenone), thus inducing a deep influence on the final aroma of the wine. Combination of both sensory and chemical data arises as a major tool to monitor the different patterns of aroma release and formation from selected yeast strains during the winemaking process.     

Bound aroma compounds of Marmajuelo and Malvasía grape varieties and their influence on the elaborated wines

Marmajuelo and Malvasía are two white grape varieties grown in Spain (Canary Islands), the former only in the Canary Islands, while the latter is a variety widely spread throughout the world. At the present time, the oenological potential of these varieties grown in the Canaries has not yet been studied. Aroma precursors in musts and skins, and free volatiles in wines were determined in samples of both varieties. Aroma precursors of must and skins were isolated by absorption on XAD-2 resin, and the aglycone liberated by means of acid hydrolysis. Free volatiles from wines and from aroma precursors were extracted with dichloromethane and then analysed by GC–MS. The analysis of glycosidic aroma precursors showed that Malvasía variety presented higher contents of terpenes in grapes than those of Marmajuelo variety. In addition, some precursors of benzenic compounds presented higher contents in the musts of Malvasía with respect to those in the musts of Marmajuelo. The main difference in wine volatile composition was that cis-3-hexen-1-ol, ethyl acetate and γ-nonalactone compounds showed a significantly higher mean content in Malvasía wines than in Marmajuelo wines. Among the aroma precursors analysed, only α-terpineol, linalool oxides, 4-allyl-2,6-dimethoxyphenol, 2-methoxy-4-vinylphenol, 4-hydroxybenzaldehyde, vanillin and benzyl alcohol showed contents in grapes comparable to the levels observed in wine volatile compounds.     

4-Ethylphenol, 4-ethylguaiacol and 4-ethylcatechol in red wines: Microbial formation,prevention, remediation and overview of analytical approaches

The presence of 4-ethylphenol, 4-ethylguaiacol and 4-ethylcatechol in red wines affect negatively their aroma conferring horsy, barnyard, smoky and medicinal aromatic notes. These volatile phenols formed from free hydroxycinnamic acids and their ethyl esters by Dekkera/Brettanomyces yeasts, can contaminate wines. Their formation can cause serious negative economic impact to the wine industry worldwide as consumers tend to reject these wines. For these reasons various preventive and remedial treatments have been studied. This review summarises the wine microbial volatile phenols formation, preventive measures during winemaking and remedial treatments in finished wines along with their advantages and limitations for dealing with this sensory defect and impact on wine quality. Also it is important to control the levels of volatile phenols in wines using fast and convenient analytical methods namely with a detection limit below their olfactory perception threshold. The analytical methods available for quality control and performance characteristics as well their advantages and disadvantages when dealing with a complex matrix like wine are discussed in detail.     

Impact of agronomic practices on grape aroma composition: a review

Aroma compounds are secondary metabolites that play a key role in grape quality for enological purposes. Terpenes, C₁₃-norisoprenoids, phenols, and non-terpenic alcohols are the most important aroma compounds in grapes and they can be found as free volatiles or glycoconjugated (bound) molecules. The non-volatile glycosylated group is the largest, and it is present in all varieties of Vitis vinifera (L.), the most widely used species for wine production. These aroma precursors represent the reserve of aroma molecules that can be released during winemaking. Their relative and absolute concentrations at fruit ripening determine the organoleptic value of the final product. A large range of biotic and abiotic factors can influence their biosynthesis in several ways. Agronomic practices such as irrigation, training systems, leaf removal, and bunch thinning can have an effect at plant level. The spraying of stimulatory compounds on fruit at different developmental stages has also been shown to modify metabolic pathways at fruit level with some impact on the aroma composition of the grapevine fruit. Viticulturists could act to promote aroma precursors to improve the aromatic profile of grapes and the wine ultimately produced. However, agronomic practices do not always have uniform results. The metabolic and physiological changes resulting from agronomic practices are unknown because there has not been sufficient research to date. This review presents the state of the art regarding the influences of vineyard agronomic management on the biosynthesis of grape aroma compounds. Although literature regarding the topic is abundant there are still many unknown biological mechanisms involved and/or that have been insufficiently studied. The aim of this work is therefore to find the gaps in scientific literature so that future investigations can focus on them. © 2018 Society of Chemical Industry