Experimental Wines Research Articles

Effect of Lachancea thermotolerans on the Formation of Polymeric Pigments during Sequential Fermentation with Schizosaccharosmyces pombe and Saccharomyces cerevisiae.

Anthocyanins in red grape musts may evolve during the winemaking process and wine aging for several different reasons; colour stability and evolution is a complex process that may depend on grape variety, winemaking technology, fermentative yeast selection, co-pigmentation phenomena and polymerization. The condensation of flavanols with anthocyanins may occur either with the flavylium ion or with the hemiacetal formation in order to produce oligomers and polymers. The kinetics of the reaction are enhanced by the presence of metabolic acetaldehyde, promoting the formation of pyranoanthocyanin-type dimers or flavanol-ethyl-anthocyanin structures. The experimental design carried out using white must corrected with the addition of malvidin-3-O-glucoside and flavanols, suggests that non-Saccharomyces yeasts are able to provide increased levels of colour intensity and larger polymeric pigment ratios and polymerization indexes. The selection of non-Saccharomyces genera, in particular Lachancea thermotolerans and Schizosaccharomyces pombe in sequential fermentation, have provided experimental wines with increased fruity esters, as well as producing wines with potential pigment compositions, even though there is an important reduction of total anthocyanins.

PCR analysis of experimental and commercial wines by means of nuclear and chloroplast SSRs

Genetic identification of varieties of grapevines in finished wines is still debated: several papers showed that DNA is extracted and analysed by PCR rather easily from the must, but few barely reproducible results have been presented for DNA extracted in wines after fermentation. This work experimented a method based on CTAB followed by silica purification with NucleoSpin Plant Kit columns to extract DNA from experimental wines of 1 year and commercial wines of 1 or 2 years. The comparison of SSR profiles of wines with those of their grapevine varieties showed that total identity was equal to 47.41% in experimental wines and to 24.31% in commercial wines. In experimental wines, three PCR replicates of three independent DNA preparations are sufficient to capture the alleles of the original grapevine variety, while in the commercial ones this possibility is related to the kind of wine and microsatellite.

Co-evolution as Tool for Diversifying Flavor and Aroma Profiles of Wines.

The products of microbial metabolism form an integral part of human industry and have been shaped by evolutionary processes, accidentally and deliberately, for thousands of years. In the production of wine, a great many flavor and aroma compounds are produced by yeast species and are the targets of research for commercial breeding programs. Here we demonstrate how co-evolution with multiple species can generate novel interactions through serial co-culture in grape juice. We find that after ~65 generations, co-evolved strains and strains evolved independently show significantly different growth aspects and exhibit significantly different metabolite profiles. We show significant impact of co-evolution of Candida glabrata and Pichia kudriavzevii on the production of metabolites that affect the flavor and aroma of experimental wines. While co-evolved strains do exhibit novel interactions that affect the reproductive success of interacting species, we found no evidence of cross-feeding behavior. Our findings yield promising avenues for developing commercial yeast strains by using co-evolution to diversify the metabolic output of target species without relying on genetic modification or breeding technologies. Such approaches open up exciting new possibilities for harnessing microbial co-evolution in areas of agriculture and food related research generally.

Impact of Saccharomyces cerevisiae Strains on Health-Promoting Compounds in Wine

Moderate wine consumption is associated with human health benefits (reduction of cardiovascular risk and neurodegenerative diseases, decrease of onset of certain cancers) attributed to a series of bioactive compounds, mainly polyphenols, with antioxidant power capable of counteracting the negative action of free radicals. Polyphenols are naturally present in the grapes, but an additional amount originates during winemaking. The aim of this work was to assess the ability of four commercial and two indigenous Saccharomyces cerevisiae strains to produce bioactive compounds (tyrosol, hydroxytyrosol, tryptophol, melatonin and glutathione) during alcoholic fermentation. In order to exclude the fraction of antioxidant compounds naturally occurring in grapes, the strains were inoculated in a synthetic must. At the end of fermentation the bioactive compounds were analysed by High-Performance Liquid Chromatography, while antioxidant activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Moreover, freeze-dried samples, originating from the experimental wines, were used to perform ex-vivo assays on cultured cells (RAW 264.7 murine macrophages) with the aim to evaluate their antioxidant and anti-inflammatory activities. The results indicated that the production of the considered bioactive compounds is a strain-specific property; therefore, the different yeast strains utilized during fermentation have different capabilities to modify the antioxidant and anti-inflammatory properties of the wine.

Schizosaccharomyces japonicus: A Polysaccharide-Overproducing Yeast to Be Used in Winemaking

Mixed starter cultures made of Saccharomyces cerevisiae EC1118 and Schizosaccharomyces japonicus #13 were inoculated in commercial grape must, and the impact of different inoculum ratios (1:1; 1:100; 1:10,000) on growth and fermentation kinetics and on the analytical profiles of the experimental wines was here evaluated. Results obtained showed that S. japonicus #13 affects S. cerevisiae growth and fermentative capability only for S. cerevisiae/S. japonicus inoculum ratio 1:10,000. The analytical profiles of the wines produced by mixed starter cultures indicated that this non-Saccharomyces yeast modulates the concentration of malic and acetic acids and of some of the most important volatile compounds, such as β-phenyl ethanol, in an inoculum-ratio-dependent fashion. Moreover, all experimental wines obtained with S. japonicus #13 in mixed cultures reached concentrations of total polysaccharides significantly higher than those obtained with pure cultures of S. cerevisiae EC1118, and total polysaccharides increased with the increase of S. japonicus #13 cell concentration. Based on these results, S. japonicus #13 might be profitably inoculated in combination with S. cerevisiae EC1118 to enhance wine complexity and aroma and to improve wine stability by increasing the final concentration of polysaccharides.

Sauvignon Blanc aroma and sensory profile modulation from high fining rates

Background and Aims Fining agents are commonly used in the wine industry to improve many aspects of juices and wines. This study focused on the modulation of the aroma chemistry and sensory profiles of Sauvignon Blanc wines through high rates of juice fining. Methods and Results Sauvignon Blanc press fraction juices were fined with three commercially available agents at high rates. The juices were then fermented and their aroma profiles analysed using GC–MS. Pre-fermentation fining with activated carbon significantly reduced the amount of linalool and hexan-1-ol in the experimental wines. Furthermore, the use of gelatin as a fining agent may have influenced the presence of ethyl (dihydro)cinnamate and benzyl alcohol. Other aroma compounds were also influenced by high rates of pre-fermentation fining during the experimental winemaking. Conclusions The choice of pre-fermentation fining agent applied at a high rate has the ability to significantly influence the concentration of aroma compounds in Sauvignon Blanc wine. In particular, activated carbon and gelatin may decrease or increase compounds of interest, respectively. Significance of the Study This study may assist winemakers with their fining decisions during harvest as it showed how numerous aroma compounds can be influenced by fining agents.

Evaluation of the Nietvoorbi j Wine Score Card and Experimental Wine Panelists Utilizing Pattern Recognition Techniques

Principal component analysis (PCA) was applied to four cultivar wines, submitted repetitively amongst more than 450 experimental wines, to a sensory evaluation panel of 18 members who used a scoring system comprising overall wine quality and 11 wine descriptors. Inconsistent judges could be eliminated by the evaluation of scatter diagrams. After eliminating 11 judges, the scores of the remaining 7 were used to evaluate the score card in terms of weights placed on individual descriptors in a multiple regression equation, which related the 11 parameters to overall quality scores. Deviations from actual score card weights are discussed in terms of previous PCA analyses, and it is argued that both cultivar and the composition of a mixed data set with respect to these factors, could affect the relative importance of certain parameters. Fitting a similar equation to a large data set consisting of about 480 wines, comprising 23 different cultivars, confirmed the need for further investigations concerning relative score card weights, as well as a critical evaluation of score card parameters for evaluating widely diverging experimental wines.

Effect of pH, Temperature and S02 Concentration on the Malo-Lactic Fermentation Abilities of Selected Bacteria and on Wine Colour

Thirty malo-Iactic bacterial cultures, isolated from red wines from 10 Western Cape wineries, were tested for their malo-Iactic fermentation abilities in Cinsaut wine. Each isolate was tested at S02 concentrations of 34 and 61 mg/C pH levels of 3,5 and 3,8, and temperatures of 15 and 20 °C. The wines were inoculated after alcoholic fermentation, and malo-Iactic fermentation was followed by paper chromatography tests for the following 5 months. At this point the colour of each oottle of wine which had undergone malo-Iactic fermentation, was determined and the colour loss calculated. The lower S02 concentration and higher temperature were significantly more favourable to malo-lactic fermentation. Two of the Leuconostoc oenos isolates completed malo-Iactic fermentation highly significantly more rapidly than nearly all other L. oenos, Lactobacillus and Pediodoccus isolates under the conditions tested. No great differences, few of which were significant, were found amongst the other isolates. The higher S02 concentration was the most important single factor causing colour loss in the experimental wines. The 30 bacterial cultures tested did not produce significantly different losses in colour.

Glycerol in South African Table Wines: An Assessment of its Relationship to Wine Quality

Glycerol is an important by-product of glycolysis and is quantitatively one of the major components of wine. While the physicochemical and sensory characteristics of pure glycerol are well established, the impact of varying levels of glycerol on general wine quality remains a topic of debate. Previous reports have relied on limited numbers of either commercial or experimental wines to assess the role of glycerol, leading to contradictory conclusions. Here we report on a large-scale assessment of the relationship between glycerol concentration and wine quality, based on the analysis of a significant number of commercial South African table wines of adjudged quality. The mean glycerol concentrations of 237 dry red (10.49 g/L), 158 dry white (6.82 g/L), 22 off-dry white (6.55 g/L), 16 special late harvest (8.26 g/L) and 14 noble late harvest wines (15.55 g/L) were found to be associated with considerable variation within each respective style. The final glycerol concentrations were significantly associated with the wine style (P 0.05). The mean glycerol concentrations for South African dry red wines were significantly higher than those of dry white and off-dry white wines. Wine quality could not be significantly associated with glycerol concentrations in the dry red wines (P>0.05). For the dry white, off-dry white and late harvest wines this association was significant (P<0.05), although the exact nature of the association was somewhat different for the respective styles. Despite this positive statistical association, the observed differences between the mean glycerol concentrations of dry white and off-dry white wines of different quality ratings were too small to be of major practical value. The relationship between glycerol concentration and wine quality is reassessed on the basis of results obtained in this study as well as on recent reports in the literature.

Industrial scale fining influences the aroma and sensory profile of Sauvignon blanc

Press fraction juice is generally considered to be of a lower quality than free run and due to excess skin and oxygen contact may result in wines with harsh phenolic profiles. In this situation, fining agents may be used to aid the removal of certain polyphenols. During this study, commercial fining agents were employed to fine two sets of Marlborough press fraction juice in industrial sized trials. The concentrations of 23 aroma compounds were determined for the resulting experimental wines, along with a simple sensory analysis. Results showed that both juice and fining agent choice had the ability to influence the wines aroma chemistry. For instance, the Wairau valley juices fined with activated carbon gave an average 3-mercaptohexanol level of 262 ng/L, less than the corresponding control (415 ng/L) which received no fining agent addition. 3-Mercaptohexyl acetate was also lower in these activated samples at an average level of 180 ng/L, compared to 268 ng/L for the control. Reductions of linalool and β-citronellol by activated carbon fining were also observed during this trial. Ethyl (dihydro)cinnamate increased with the use of gelatin from 0.51 and 0.42 μg/L in the control wines to 1.18 and 1.38 μg/L for each juice set, respectively.

β -Phenethanol and n-hexanol in wines: Influence of yeast starin, grape variety and other factors; and taste thresholds

β-Phenethanol and n-hexanol were measured by gas chromatography in a wide range of commercial and experimental wines. Commercial wines ranged from 5 to 74 ppm β-phenethanol and 1.3 to 12 ppm n-hexanol. Dry red wines and fino sherries were high in p'-phenethanol, and ports, muscats (both sweet dessert wines) and dry red wines were high in n-hexanol. The strain of yeast strongly influenced formation of β-phenethanol. Mean yields by eight yeasts (Saccharomyces) during fermentation of grape juices from three varieties of Vitis vinifera under comparable conditions ranged from 5.6 to 20 ppm. The strain of yeast had little effect on amounts of n-hexanol in the wines. Varieties of V. vinifera differed in amounts of β-phenethanol and n-hexanol formed in the wines made therefrom, irrespective of the yeast strain used. Wines made from Shiraz (Syrah) grapes were characterised by high levels of fi-phenethanol in comparison with white grape varieties examined. The year of vintage influenced amounts of β-phenethanol in wines, and the soil type and viticultural area also effected the amounts of both β-phenethanol and n-hexanol formed. More β-phenethanol was formed by fermentation at 15° C and 25° C than at 35° C, and more was formed at pH 3.5 and 4.0 than at pH 3.0. n-Hexanol content was not influenced significantly by either temperature of fermentation or pH of the must. Addition of β-phenylalanine to the must resulted in formation of more β-phenethanol by fermentation, and the mechanism of formation of both β-phenethanol and n-hexanol is discussed . Taste thresholds were measured as minimum detectable differences in a Riesling dry white wine. Values for different tasters ranged from 30 to > 200 ppm for β-phenethanol (10 tasters) and 4 to > 30 ppm for n-hexanol (9 tasters). Added β-phenethanol, but not n-hexanol, was considered to improve the quality of the wine.

Typicité sensorielle de vins de l'AOC Coteaux du Layon et acceptabilité par les acteurs (professionnels et consommateurs) de vins avec des titres d'alcool volumique plus faibles

In order to maintain an optimum sugar / acid balance in a changing context, winegrowers of the Coteaux du Layon PDO, a sweet wine of the middle Loire valley, wish to know if a final alcohol content (TAV) lower than the minimum imposed by the regulation of the PDO (11% vol. today) would affect the typicality of the wines. To answer this question, a study was carried out in 4 steps. 1) To know the expected typicality of these wines, focus groups were conducted with 26 professionals. 2) In order to assess the acceptability of lower TAV wines, based on a sample of 24 wines (commercial wines and experimental wines with TAV between 8% vol. and 10% vol.), 31 professionals scored levels of exemplarity. 3) A trained panel made a fine sensory description. 4) Finally, a selection of 8 wines from these 24 were evaluated by 163 consumers, they scored levels of preference. The results of steps 1) and 2) show a strong consensus among professionals to assess the exemplarity of wines. Experimental wines obtained exemplary scores above the average of the scale and can therefore be considered as good examples. In step 3), the trained panel generated the sensory attributes to describe the wines: 21 descriptors of odors and aromas and 6 of flavors, which reveal the sensory complexity of the wines. In stage 4), in general, the 8 wines evaluated by the consumers were all appreciated. The results suggest that a sufficiently high amount of residual sugar content would enhance the acceptability of lower TAV wines by both professionals and consumers. The winegrowers of the syndicate of Coteaux du Layon PDO thus have factual elements to update the specification of the PDO (decreasing the minimum TAV threshold), in interaction with INAO (the French national institute of origin and quality).

Effect of Some Oenological Practices Applied Before the Alcoholic Fermentation on the Chemical Composition and Sensory Characteristics of White Wines

Abstract The effect of the oenological practices, maceration and maceration with the addition of aromatic enzyme before the alcoholic fermentation on the composition, aromatic components and organoleptic profile of experimental wines from the local varieties Dimyat, Muscat Vrachanski and the newly-selected variety Plevenska Rosa was studied. The investigation was carried out during the period 2013–2014, with grapes and wine from the studied varieties grown in the soil and climatic conditions of the town of Pleven (Central Northern Bulgaria). The applied technological practices had increased the sugar-free extract and the total phenolic compounds content in the experimental samples. The highest rates for these indicators revealed the variants of Plevenska Rosa variety. The amount of esters and higher alcohols was greater in the wines obtained after maceration and maceration with the addition of aromatic enzyme in the grape must. The total esters concentration was the highest in the samples of the aromatic varieties Muscat Vrachanski and Plevenska Rosa. There was not observed a direct correlation between the applied oenological practices, enhancing the extraction and the aromatic components content in the experimental variants and their organoleptic profile.

Effects of Soil Parent Material and Climate on the Performance of Vitis vinifera L. cvs. Sauvignon blanc and Cabernet Sauvignon - Part II. Climate, Leaf Analysis, Juice Analysis and Wine Quality

A five-year investigation (2004/05 to 2008/09) was carried out in two Sauvignon blanc and two Cabernet Sauvignon vineyards in the Helderberg area, Western Cape, South Africa. Soils, derived mainly from granite and shale, were identified in each vineyard. Climatic parameters were measured, while leaves and juice were analysed. Experimental wines were prepared and evaluated annually. The nutritional status of the leaf blades and petioles was not affected by soil parent materials in a consistent pattern. Juice N of grapevines on the shale-derived soil was usually higher than that of vines on the granite-derived soil. The effect of soil parent material on Sauvignon blanc wine style appeared to have been more distinct at the locality where wine quality was highest. At this locality, wine from the grapevines on shale-derived soil (higher water-holding capacity) was best in 2004/05 (dry season), while the reverse was true in the 2007/08 season (wet). The style and/or quality of Cabernet Sauvignon wines were affected to a greater extent by differences in soil parent materials, relative to Sauvignon blanc. Differences were especially noticeable during the cooler and wetter seasons. Better drainage in the case of the granite-derived soils, due to the higher coarse sand fraction, may have played a positive role during these seasons.

Influence of physical and chemical characteristics of wine grapes on the incidence of Penicillium and Aspergillus fungi in grapes and ochratoxin A in wines

The incidence of filamentous fungi and toxin levels in grapes and wines varies depending on the variety of grapes, the wine region, agricultural practices, weather conditions, the harvest and the winemaking process. In this sense, the objective of this study was to evaluate the diversity of Aspergillus and Penicillium fungi isolated from wine grapes of the semi-arid tropical region of Brazil, evaluate the presence of ochratoxin A (OTA) in the experimental wine and verify if there is a correlation between occurrence of these fungi and the physicochemical characteristics of the wine grapes grown in the region. For the isolation of fungi we used the direct plating technique. The presence of OTA in the experimental wine was detected by high-performance liquid chromatography. The species found were Aspergillus niger, A. carbonarius, A. aculeatus, A. niger Aggregate, A. flavus, A. sojae, Penicillium sclerotiorum, P. citrinum, P. glabrum, P. decumbens, P. solitum and P. implicatum. All isolates of A. carbonarius were OTA producers and all P. citrinum were citrinin producers. The highest concentration of OTA was found in red wine (0.29μg/L). All species identified in this study, except A. flavus, showed a positive correlation with at least one physicochemical parameter assessed, highlighting the pectin content, total sugar, total acidity and phenolic compounds.

A Multivariate Methodological Approach to Relate Wine to Characteristics of Grape Composition: The Case of Typicality

Typicality is defined as the characteristics of a Protected Designation of Origin (PDO) wine related to a terroir. In the context of a PDO, a typicality assessment can be used to assess the global quality of a PDO wine. This study used a two-phase method to identify the distinctive characteristics of a PDO wine and then apply those findings to a case study of Chianti Montespertoli DOCG wine, where DOCG is the Italian acronym for PDO. A panel of wine professionals evaluated the typicality of a series of selected PDO wine samples, and a partial least squares (PLS) regression model was used to associate wine typicality and chemical composition. The model was used to predict wine typicality from the chemical composition of experimental wines (2009, 2010, and 2011 vintages) produced from grapes growing in the PDO area. Finally, regression coefficients of the PLS model were analyzed to select which grape chemical parameters were significant in describing the typicality of the wine. These highlight the most important factors to manage during winemaking to ensure the typicality of this wine.

Influence of leaf removal and reflective mulch on phenolic composition and antioxidant activity of Merlot, Teran and Plavac mali wines (Vitis vinifera L.)

Two years study was conducted to evaluate if leaf removal and red geotextile reflective mulch affect phenolic composition of wines from three red wine grape cultivars, Merlot, Teran and Plavac mali (Vitis vinifera L.). Leaf removal (LR) and reflective mulch (RM), made from weave of aluminum platelets protected by a transparent film and sewn together with red polypropylene threads, were tested separately and combined (LR+RM) on vines of Merlot, Teran and Plavac mali in 2009 and 2010 years, and compared with untreated control. All treatments were applied at veraison. LR had the strongest influence on phenolic composition of experimental wines, particularly in terms of increasing gallic acid, catechin, malvidin-3-glucoside, delphinidin-3-glucoside and peonidin-3-glucoside content. LR+RM resulted in higher gallic acid and malvidin-3-glucoside concentrations. RM treatment had the least effect on phenolic composition of wines but still affected higher epicatechin and gallic acid content. The total phenols, anthocyanins and flavan-3-ols contents in wines exhibited strong correlation with antioxidant activity.

Genetically engineered Oenococcus oeni strains to highlight the impact of estA2 and estA7 esterase genes on wine ester profile

Besides deacidifying wine, Oenococcus oeni bring significant changes in the chemical composition of wine by releasing esters by the action of their own esterases. The impact of O. oeni esterases remains relatively unexplored. Four esterase genes were identified from O. oeni genome (estA2, estA7, estC, and estB). The dual objective of this study was, first to use a genetic tool enabling the expression of esterase genes in enological conditions and, second, to investigate the impact of O. oeni esterase gene expression during winemaking on wine aromatic profile. Both estA2 and estA7 genes were successfully cloned and expressed in O. oeni and recombinant strains were inoculated in Aligoté wine to initiate malolactic fermentation (MLF). Ester profile of experimental wine was established by SPME-GC-MS. EstA2 caused significant decreases in the concentrations of isoamyl acetate, ethyl hexanoate, isobutyl acetate, and hexyl acetate, by 42.7%, 23.4%, 51.5%, and 28.9%, respectively. EstA2 has preferential hydrolytic activity toward acetate esters from higher alcohols. EstA7 has synthetic activity toward hexyl acetate with a significant 22.7% increase. This study reports the first efficient expression system enabling the production of a functional protein in O. oeni in enological conditions.

Pre-fermentation fining effects on the aroma chemistry of Marlborough Sauvignon blanc press fractions

In the wine industry, fining agents are commonly used with many choices now commercially available. Here the influence of pre-fermentation fining on wine aroma chemistry has been explored. Free run and press fraction Sauvignon blanc juices from two vineyards were fined using gelatin, activated carbon, polyvinylpolypyrrolidone (PVPP) and a combination agent which included bentonite, PVPP and isinglass. Over thirty aroma compounds were quantified in the experimental wines. Results showed that activated carbon fining led to a significant (p<0.05) concentration decrease of hexan-1-ol and linalool in the experimental wines when compared to a control, consistent across all vineyard and fraction combinations. Other aroma compounds were also influenced by fining agent, even if vineyards and press fractions played a crucial role. This study confirmed that fining agents used pre-fermentation can influence wine aroma profiles and therefore needs specific tailoring addressing style and origin of grape.

Toward automated chromatographic fingerprinting: A non-alignment approach to gas chromatography mass spectrometry data

In contrast to targeted analysis of volatile compounds, non-targeted approaches take information of known and unknown compounds into account, are inherently more comprehensive and give a more holistic representation of the sample composition. Although several non-targeted approaches have been developed, there's still a demand for automated data processing tools, especially for complex multi-way data such as chromatographic data obtained from multichannel detectors. This work was therefore aimed at developing a data processing procedure for gas chromatography mass spectrometry (GC–MS) data obtained from non-targeted analysis of volatile compounds. The developed approach uses basic matrix manipulation of segmented GC–MS chromatograms and PARAFAC multi-way modelling. The approach takes retention time shifts and peak shape deformations between samples into account and can be done with the freely available N-way toolbox for MATLAB. A demonstration of the new fingerprinting approach is presented using an artificial GC–MS data set and an experimental full-scan GC–MS data set obtained for a set of experimental wines.