Oenological Characteristics Research Articles

Biodiversity and oenological attitude of Saccharomyces cerevisiae strains isolated in the Montalcino district: biodiversity of S. cerevisiae strains of Montalcino wines.

The biodiversity of Saccharomyces cerevisiae was studied in the Montalcino area (Italy). Two wineries were involved in the study, which compared the genotypic and oenological characteristics of the S. cerevisiae strains isolated in spontaneous fermentations. After isolation yeasts were identified by 26S rRNA gene sequence analysis, and S. cerevisiae strains were characterized through interdelta sequence analysis (ISA). Oenological tests were performed in synthetic grape must by varying the magnitude of the main wine-imiting factors. The evolution of alcoholic fermentation was monitored by measuring sugar consumption and flow cytometry. The results revealed the prevalence of S. cerevisiae from the third day of fermentation and the presence of a wide range of S. cerevisiae strains having ISA profiles characteristic of each winery. From an oenological point of view, the features of such strains, in terms of resistance to wine-limiting factors, seemed to be linked to the main oenological variables applied in the production process of each winery. Extreme fermentation temperatures and copper residues are the variables that mostly depress the yeast population, in terms of fermentation rate and cell viability. Flow cytometry revealed the different impact of limiting factors on the viability of yeast by the quantification of the ratio between live/dead yeast cells of each strain, suggesting different mechanisms of inhibition, for instance stuck of cell growth or cell killing, in response to the different stress factors.

Fungal community diversity and fermentation characteristics in regional varieties of traditional fermentation starters for Hong Qu glutinous rice wine

Hong Qu glutinous rice wine (HQ wine) is a traditional alcoholic beverage produced in China by fermenting cooked rice using a fermentation starter prepared with the fungus Monascus purpureus. This starter (Hong Qu, HQ) is made empirically by open spontaneous fermentation that is hard to control and standardize, resulting in inconsistent wine quality. This study investigates representative HQ samples from a large geographic region. It explores fungal microbiome compositions, identifies characteristic differences important for the production of various HQ wine styles, and reveals the key fungi responsible for HQ wine fermentation characteristics. The source of the HQ inoculum was found to be the main factor influencing fungal community composition and diversity, followed by processing technology and geographical distribution. Linear discriminant analysis effect size (LEfSe) uncovered 14 genera as potential biomarkers to distinguish regional varieties of HQ. Significant differences were also found in fermentation characteristics such as liquefying power (LP), saccharifying power (SP), fermenting power (FP), total acid content (TA) and liquor-producing power (LPP). The key fungi responsible for LP (5 genera), SP (3 genera), FP (1 genera), LPP (4 genera), and TA (4 genera) were determined using redundancy correlation analysis. Finally, Spearman’s correlation analysis indicated that LPP shows a strong positive correlation with FP and LP, while TA displays a strong negative correlation with FP. The results of this study may be utilized to prepare consistently high quality, next-generation HQ by better controlling fungal community structures, and to design fermentation processes for HQ wines with desirable oenological characteristics.

OENOLOGICAL CHARACTERIZATION OF SOME YEAST STRAINS ISOLATED FROM THE IASI VINEYARDROMANIA

This study investigated the oenological potential of indigenousSaccharomyces and non-Saccharomyces yeasts isolated from different stages of the natural must fermentation process. Screening of extracellular enzymatic activities was performed on agarized media in which the following substrates were added: arbutin, cellobiose, Tween 80, tributyrin, casein and citrus pectin, to highlight the activity of enzymes: ßglucosidase, esterase, lipase, protease and pectinase. Among the 30 Saccharomyces cerevisae strains tested, 37% showed very low β-glucosidase activity, 100% showed esterase activity, 40% lipase activity, 90% protease activity and 53% pectinase activity.The non-Saccharomyces strain tested showed β-glucosidase, esteraseand protease activity. Tolerance to ethanol was assessed in YPD medium with ethanol concentrations of 5, 10 and 15% (v/v) by yeast culture development index.At 15% ethanol, development of all tested strains were inhibited. In the case of SO2 tolerance, decrease in strains development was inversely correlated with the increase in potassium metabisulphite concentration, up to 200 mg/L. Only four Saccharomyces strains showed specific oenological characteristics and were selected to be tested in mixed and/or sequential cultures to obtain wines with improved sensory features.

Oenological characteristics of Vitis vinifera L. Cabernet Sauvignon grapes from vineyards treated with ozonated water

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Use of grape racemes from Grillo cultivar to increase the acidity level of sparkling base wines produced with different Saccharomyces cerevisiae strains.

The most important oenological characteristics of high-quality sparkling wines are aromatic aspect, taste persistence, perlage, high levels of acidity and low pH. Due to hot climate and reduced rainfall that characterize Sicily region, white grape varieties such as Grillo cultivar cultivated in this area are characterized by very low concentrations of malic and tartaric acids. Grillo cultivar is characterized by an intense production of raceme grapes with low pH and high content of tartaric and malic acids. These fruits possess the chemical properties useful to increase the amounts of acids in the final wines. With this in mind, the present research was carried out to test the ability of four Saccharomyces cerevisiae strains (CS182, GR1, MSE13 and MSE41) to ferment a raceme must with a pH of 2.9 at two concentrations (14° and 16° Babo degree) of total sugars. The inoculation of the strains was performed after a preadaptation at pH 2.5. The chemical parameters and kinetics of the fermentations were monitored. The experimental sparkling base wines were characterized by a very high total acidity with 16-17 g/L of tartaric acid and 9-10 g/L of malic acids. On the other hand, ethanol was detected at low values in the range 9-10% (v/v). The base wine obtained with GR1differed in their high acidity values, whereas trials inoculated with CS182 showed more intense odors and exotic fruit. Experimental wines produced in this study represent an innovative strategy for "blending wines" to produce sparkling wines in dry Mediterranean climate.

Selection and oenological comparison of Taiwan Black Queen grape wine yeasts

More than hundreds of private wineries have been established since the Taiwan Tobacco and Alcohol Administration Act was enacted on April 19, 2000. It is then essential to screen local wine yeast in order to develop quality wine with unique flavor. Black Queen grape is a main ingredient for red wine brewing in Taiwan. In this study, ethanol productivity of yeasts isolated from spontaneous fermentation of Black Queen grape must (17 and 30 °Brix) was determined. Seven yeasts identified as Saccharomyces cerevisiae by Biolog System with higher ethanol productivity were individually inoculated into Black Queen grape must to undergo fermentation at 25°C for 14 days. The ethanol contents and volatile acidity in wine were above 15% (v/v) and below 0.7 g/L, respectively. Compared to commercial wine yeasts A, B and C, HP01 fermented red wine contained the highest total ester content, color intensity, taste grade, and overall preference value. On the other hand, HS13 fermented red wine contained the highest ethanol, higher alcohols, fatty acids and phenolic compounds content. The mtDNA restriction fragments profiles of these two wine yeast strains were different from those of other yeast strains. Due to their superiority in oenological characteristics, HP01 and HS13 can be applied in Black Queen red wine brewing to produce red wine with unique flavor.

Sequential Non-Saccharomyces and Saccharomyces cerevisiae Fermentations to Reduce the Alcohol Content in Wine

Over the last decades, the average alcohol content of wine has increased due to climate change and consumer preferences for particular wine styles that resulted in increased grape sugar levels at harvest. Therefore, alcohol reduction is a current challenge in the winemaking industry. Among several strategies under study, the use of non-conventional yeasts in combination with Saccharomyces cerevisiae plays an important role for lowering ethanol production in wines nowadays. In the present work, 33 native non-Saccharomyces strains were assayed in sequential culture with a S. cerevisiae wine strain to determine their potential for reducing the alcohol content in Malvar white wines. Four of the non-Saccharomyces strains (Wickerhamomyces anomalus 21A-5C, Meyerozyma guilliermondii CLI 1217, and two Metschnikowia pulcherrima (CLI 68 and CLI 460)) studied in sequential combination with S. cerevisiae CLI 889 were best able to produce dry wines with decreased alcohol proportion in comparison with one that was inoculated only with S. cerevisiae. These sequential fermentations produced wines with between 0.8% (v/v) and 1.3% (v/v) lower ethanol concentrations in Malvar wines, showing significant differences compared with the control. In addition, these combinations provided favorable oenological characteristics to wines such as high glycerol proportion, volatile higher alcohols, and esters with fruity and sweet character.

Oenological Characteristics of Fermented Apple Musts and Volatile Profile of Brandies Obtained from Different Apple Cultivars.

Volatile profile of spirits is the most important factor, because it can contribute to pleasant flavor. The aim of the study was to determine the impact of dessert apple cultivar used for fermentation on the concentration of volatile compounds in apple spirits. SPME-GC-MS (solid-phase microextraction- gas chromatography- mass spectrometry) method enables the detection of 69 substances and GC-FID (gas chromatography - flame ionization detector) 31 compounds. Characteristic volatiles for brandies obtained from Topaz were limonene, myrcene, methyl valerate and 1,1-diethoxy-propane, from Rubin—β-citronellol and isopropyl acetate, Elise—limonene, myrcene benzyl acetate and isopropyl acetate, Szampion—β-citronellol, Idared—1,1-diethoxy-propane and Jonagored—ethyl trans-4-decanoate. Of the ten analyzed apple spirits, those obtained from Topaz, Rubin and Elise cultivars demonstrated the most diverse profile of volatile compounds. Moreover, their oenological parameters that are the most important in the production of alcoholic beverages were the most favorable. On the other hand, the content of sugars was relatively low in Elise must, while it was highest in Topaz must, which later on translated into differences in alcohol content. Brandies obtained from Gloster contained the smallest concentrations of esters and terpenes. Results of the sensory analysis showed that highest rated brandies were obtained from Topaz, Rubin, Elise and Florina.

Diversity of Saccharomyces cerevisiae strains associated to racemes of Grillo grape variety.

The most important oenological characteristics of high-quality sparkling wines are high content of acidity and low pH. Racemes are late-maturing grapes of Grillo variety characterized by low pH and high content of tartaric and malic acids and, due to their intrinsic characteristics, might represent an interesting technological solution to increase acid quality of base sparkling wine. To this purpose, the use of yeasts able to ferment grape must at very low pH is mandatory for the success of the process. In this work, 261 Saccharomyces cerevisiae isolated from spontaneous vinifications of Grillo grape racemes were subject to intraspecific characterization by interdelta analysis which evidenced a total population consisting of 82 strains which were screened for their basis of technological traits including SO2 and alcohol tolerance, flocculence, growth at low temperatures and qualitative features such as H2S production. A total of 11 strains with interesting technological performance in vitro were inoculated into musts obtained from racemes of Grillo grape variety and microfermentation were monitored. For the first time an ecological investigation of yeast associated to raceme grapes has been carried out and provided an innovative strategy to improve the acidity of a Sicilian sparkling base wine from Grillo grape variety.

Thiol precursors in Vitis mould-tolerant hybrid varieties.

Over recent years, a new wave of disease-tolerant to mildew varieties has flooded the viticulture sector, for reasons of human safety and economic expediency. These hybrid grape cultivars are selected mainly on the basis of their intrinsic capability to counter the attack of the main fungal diseases that affect grape production, such as downy mildew and powdery mildew. However, their organoleptic and oenological characteristics have not yet been studied in depth for purposes of both juice and wine production, due to the high number of newly proposed germplasms and the lack of information about their adaptability to different environments. This work examines the thiol aroma precursors concentration in 64 red and white disease-tolerant hybrid varieties in the vine germplasm collections of Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria-Viticulture and Enology Research Center and Fondazione Edmund Mach, both from the north-east of Italy. All cultivars showed the presence of 3-mercaptohexan-1-ol (3MH) precursors, ranging from 4.4 to 1141 μg kg-1 for 3-S-glutathionyl hexan-1-ol (GSH-3MH), and from 0.3 to 136 μg kg-1 for 3-S-cysteinyl 3-hexan-1-ol. The concentration of GSH-3MH exceeded 600 μg kg-1 in eight varieties, with values comparable to those of the richest Vitis vinifera reported so far. On average, red grapes showed higher concentrations of 3MH precursors than white ones did. Only two hybrids had 4-mercapto-4-methylpentan-2-one (4MMP) precursors over the limit of quantification, albeit with a much higher concentration than those normally reported in Sauvignon Blanc. This is the first detailed survey of 3MH and 4MMP precursors carried out taking into account a considerable number of hybrid grape varieties. The results show that some of these varieties could be interesting for the production of tropical juices or tropical-aromatic wines and soft drinks, through the enzymatic liberation of thiol aromas, as well as for the production of aromatizing tannins to be used in the food industry. © 2020 Society of Chemical Industry.

Population and oenological characteristics of non-Saccharomyces yeasts associated with grapes of Northwestern Argentina.

Yeasts population associated with grapes from Northwest Argentina, a region with a significant vine-growing increase over the past years, was evaluated. Ten species of non-Saccharomyces yeasts were identified from four grape varieties (Malbec, Merlot, Syrah and Torrontes) being Hanseniaspora uvarum the dominant species. Typing of isolates revealed genetic variability within Hanseniaspora genus and also high variability was observed according to their oenological characteristics. Based on the oenological properties, the most adequate strains as starter cultures were H. uvarum HuT7, HuMe15, HuS16, H. vineae HvT-mc1 and Metschnikowia pulcherrima MpT2/MpT3. These selected yeasts exhibited moderate resistance to SO2, reduced values of volatile acidity, null or low production of H2S, high levels of enzymes related to aroma and did not produce killer toxins. Further studies using mixed cultures of these non-Saccharomyces strains and S. cerevisiae are needed to validate the contribution of selected indigenous yeasts on wine organoleptic characteristics.

Perfil aromático de vinhos ‘Canaiolo Nero’ em regiões de altitude de Santa Catarina

Highlands are a new frontier to produce fine wines in the Southern region of Brazil (27o 12' 24 S, 51o 06' 96 W, 1211 m altitude) and has presented specific oenological characteristics with a good adaptation of some varieties, among them, Canaiolo nero. To characterize the wines of this region, during the 2012 and 2014 harvests the volatile compounds were determined through the MHS-SPME-GC-MS technique. The grapes were harvested, and samples analyzed in triplicate. The positive identification of the volatile compounds was performed by comparing the experimentally obtained mass spectrum and retention index with the reference spectra and retention indices available in the literature. Four consecutive extractions were used for quantitative evaluation to avoid a matrix effect. Odor activity value was calculated from the perception threshold for each evaluated compound. The mean soluble solids content was 21.55 o Brix, and total acid content was 81.0 meq L -1 ; the mean weight of the clusters was 176 g, and the productivity was 2.2 tons per hectare (espalier – 1.5 m × 3.0 m). Thirty-one volatile compounds were identified and quantified in the analyzed samples. The major components were the aromatic alcohol 2-phenylethanol (38.364 µg L -1 ), and the esters diethyl succinate (6.357 µg L -1 ) and ethyl acetate (2.005 µg L -1 ); and the compound of class C6, 1-hexanol (3.2 µg L -1 ). Odor activity values showed the compounds that contribute the most to the aroma of the analyzed wines, highlighting ethyl isovalerate (OAV 394.38), ethyl hexanoate (OAV 9.22), ethyl cinnamate (OAV 8.62) ethyl isobutanoate (OAV 5.59), β-damascenone (OAV 2.44), hexanoic acid (OAV 4.03), octanoic acid (OAV 3.64) and isoamyl acetate (OAV 3.01). These results showed the aroma characteristics of Santa Catarina wines of the Canaiolo nero variety, especially fruity aromas of apple, green apple, strawberry, plum and banana; and floral aroma of violet and roses.

Impact of Grape Temperature at Pressing on Organic Acids and Oenological Characteristics of Méthode Cap Classique Wines

Maintaining the chemical composition of a wine is essential for the wine industry. Although the sugar-acid balance of a wine is of primary sensory importance, individual acids and oenological parameters are equally important. The main focus of this study was to investigate the impact of grape temperature at harvest, on the oenological volatile acidity (VA), titratable acidity (TA), pH and alcohol levels and organic acid (citric, malic, pyruvic and succinic) characteristics of Methode Cap Classique (MCC) wines during winemaking, produced from grape cultivars obtained from two regions. Chardonnay and Pinot noir grapes were obtained from Robertson (warmer) and Elgin (cooler) regions and were subjected to different temperature treatments, i.e. 0, 10, 25 and 30 o C before further processing, including pressing, primary fermentation, blending, tirage, secondary fermentation, riddling and disgorging. Grape temperature was mostly responsible for a significantly higher pH of Robertson (0 and 10oC) and lower pH (0oC) of Elgin post-tirage wines. Chardonnay base wines from both regions that were vinified from grapes at lower temperatures (0 and 10 o C) were richer in malic- and succinic acid, while Pinot noir wines from both regions were characterised by higher malic-, citric- and pyruvic acid. Pyruvic acid was only detected after the secondary fermentations in wines from both regions. To our knowledge, this study is the first to investigate the influence of grape temperature on the oenological and organic acid characteristics of MCC wines in different regions, and throughout different production stages.

Killer Factor in Wine Yeasts and its Effect on Fermentation

The occurrence of killer factor amongst yeast strains in the Viti cultural and Oenological Research Institute (V 0 RI) yeast collection was studied. From a total of 96 strains, 85 were Saccharomyces cerevisiae of which 7 strains were killer, 9 neutral and 69 sensitive. These included some imported strains. On agar, no killer action was detected at wine pH. In fermentation studies using four grape cultivars, it was shown that where the killer yeast population was less than approximately 2,5% fermentation was not affected. At higher levels the killer yeast, in some instances, took over and completed fermentation, but the total fermentation time was never longer than that of the killer strain on its own. It was concluded that the use of a yeast strain should not hinge on its killer character but rather on its oenological characteristics.

Isolation, identification and oenological characterization of non-Saccharomyces yeasts in a Mediterranean island.

We isolated, identified and characterized yeast strains from grapes, and their fermented musts, sampled in the small island of Linosa, where there are no wineries and therefore the possibility of territory contamination by industrial strains is minimal. By traditional culture-dependent methods, we isolated 3805 colonies, distinguished by molecular methods in 17 different species. Five hundred and forty-four isolates were analysed for the main oenological characteristics such as fermentative vigour with and without sulphites, sugar consumption and production of alcohol, volatile acidity, hydrogen sulphide, glycerol and β-glucosidase. This analysis identified Kluyveromyces marxianus (seldomly used in winemaking) as the most interesting candidate yeast for the production of innovative wines. In recent years, interest is growing for wine production by non-Saccharomyces yeasts, both in research and in the industry. This study describes the yeast population of the grapes in a small-secluded island in the Mediterranean Sea, useful site for the search of new strains. Evaluation of fundamental oenological characters identifies potential best yeasts to assay in experimental vinifications. We also describe, for the first time, 14 new colony morphologies on WL Nutrient Agar, culture medium used to monitor the yeast population dynamics.

Selection and technological potential of Lactobacillus plantarum bacteria suitable for wine malolactic fermentation and grape aroma release

Lactobacillus plantarum strains have resistance mechanisms that enable them to survive and proliferate in wine, which makes them potential malolactic fermentation (MLF) starter cultures. This work focused on the technological characterization of 11 L. plantarum strains isolated from Southern Italian wines that undergo spontaneous MLF, and proposes a selection of new L. plantarum malolactic starters. These strains were characterized according to their oenological characteristics, their ability to produce biogenic amines and bacteriocins, their response to the presence of phenolic compounds, their enzymatic activities and their ability to produce wine odorant aglycones from odourless grape glycosidic aroma precursors. Finally, the malolactic activity of one selected strain was assessed in Cabernet Sauvignon wine, using two inoculation methods. L. plantarum strains tested were not producers of biogenic amines. In particular, the M10 strain showed a good resistance to high levels of ethanol and low pH, it has a good malolactic performance and β-glucosidase activity, this last one demonstrated both directly through the measurement of this enzymatic activity and indirectly by following the release of volatile aglycones from commercial and natural grape glycosidic odourless precursors. These results demonstrated the potential applicability of M10 as a new MLF starter culture, especially for high-ethanol wines.

PRECISION VITICULTURE FROM MULTITEMPORAL, MULTISPECTRAL VERY HIGH RESOLUTION SATELLITE DATA

In order to exploit efficiently very high resolution satellite multispectral data for precision agriculture applications, validated methodologies should be established which link the observed reflectance spectra with certain crop/plant/fruit biophysical and biochemical quality parameters. To this end, based on concurrent satellite and field campaigns during the veraison period, satellite and in-situ data were collected, along with several grape samples, at specific locations during the harvesting period. These data were collected for a period of three years in two viticultural areas in Northern Greece. After the required data pre-processing, canopy reflectance observations, through the combination of several vegetation indices were correlated with the quantitative results from the grape/must analysis of grape sampling. Results appear quite promising, indicating that certain key quality parameters (like brix levels, total phenolic content, brix to total acidity, anthocyanin levels) which describe the oenological potential, phenolic composition and chromatic characteristics can be efficiently estimated from the satellite data.

Oenological characteristics, amino acids and volatile profiles of Hongqu rice wines during pottery storage: Effects of high hydrostatic pressure processing

Hongqu rice wines were subjected to high hydrostatic pressure (HHP) treatments of 200MPa and 550MPa at 25°C for 30min and effects on wine quality during pottery storage were examined. HHP treatment can significantly (p<0.05) decrease the content of fusel-like alcohols and maintain the concentration of lactones in these wines. After 18months of storage, the HHP-treated wines exhibited a more rapid decrease in total sugars (9.3–15.3%), lower free amino acid content (e.g. lysine content decreased by 45.0–84.5%), and higher ketone content (e.g. 6- and 14-fold increase for 2-nonanone). These changes could be attributed to the occurrence of Maillard and oxidation reactions. The wines treated at 550MPa for 30min developed about twice as rapidly during pottery storage than untreated wines based on principal component analysis. After only 6months, treated wines had a volatile composition and an organoleptic quality similar to that of untreated wines stored in pottery for 18months.

Autochthonous yeasts with β-glucosidase activity increase resveratrol concentration during the alcoholic fermentation of Vitis labrusca grape must

Since red wine is the main dietary source of resveratrol, a well-known polyphenol that reduces coronary events in humans, different strategies have been employed in winery to achieve resveratrol-enriched wines. Yeasts-endowed β-glucosidase activity enhances free-resveratrol concentration in wine without modifying its composition or sensorial properties. Current assay screened 308 autochthonous yeast strains for β-glucosidase activity employing arbutin, esculin, cellobiose and piceid as substrates. The β-glucosidase-producer yeasts were evaluated in the must of Vitis labrusca Bordô grape to quantify resveratrol concentration before and after alcoholic fermentation. Fourteen yeasts increased the resveratrol concentration up to 102% without any significant difference and nine of these yeast strains also produced high ethanol contents. Four autochthonous Hanseniaspora uvarum β-glucosidase-producer strains showed adequate oenological characteristics and hydrolysed resveratrol-glucosides during the alcoholic fermentation of V. labrusca grape must.

Botanical Extracts Used as Wine Preservatives

The aim of the study was to eliminate the potentially harmful sulfite salts normally added to wine – based products for preservation purposes with the introduction into the wine natural products, with pronounced antioxidant activity. Frieze – dried samples taken from the plants Hippophaes and Goji Berry were added to dry white and red wines after their fermentation phase. In all sample tests the sensory and oenological characteristics remained almost unchanged compared to original samples (without the addition of natural products), although their antioxidant activity was significantly increased when leaves of the plant Hippophaes were added. Goji berry fruits and fruit of Hippophaes plant increased antioxidant activity compared to original samples.