Muscat Blanc Research Articles

Varietal classification of white wines by fluorescence spectroscopy.

The Slovak Tokaj region is one of the producers of high-quality white wine having protected designations of origin. The main grape varieties of this region are Furmint, Lipovina and Muscat blanc, which have specific sensory characteristics. This research work presents astrategy for the classification of three mentioned varieties of white wines using fluorescence spectroscopy with chemometrics. Emission and synchronous fluorescence spectra were obtained for bulk as well as diluted samples, principal component analysis (PCA) was applied for exploratory analysis and the scores of the selected PCs were used in linear discriminant analysis (LDA). For undiluted samples, the best PCA-LDA models based on either emission spectra excited at 370nm or synchronous fluorescence spectra obtained at wavelength difference of 40 and 100nm provided total correct classifications of 100, 100 and 93% for the calibration, validation and prediction steps, respectively. For diluted samples, the best PCA-LDA models (excitation at 280nm; wavelength difference of 40nm) again provided total correct classifications as mentioned above.

The effect ofSaccharomyces cerevisiaeon antioxidant system of grape leaves infected by downy mildew

In this article, results of the comparative analysis and assessment of resistance of two grape cultivars Vostorg and Muscat blanc against downy mildew disease (Plasmopara viticola) with or without the symbioteSaccharomyces cerevisiae(vine yeast) were shown. The highly resistant cultivar Vostorg with yeast pre-treatment demonstrated a high defensive capability to the pathogen due to the fast immune response. On the first day after inoculation with downy downy mildew the rapid increase in the hydrogen peroxide, which is involved the first step of the grape’s defense system induction, was observed. At the same time, the upregulation of the relative expression of the PR2 protein (β-1,3-gluconase), a key gene involved in the plant’s resistance to pathogens. The oxidative burst was not detected in the susceptible cultivar Muscat blanc for the couple of hours after inoculation with downy mildew pathogen. The significant increase of the total phenols content and expression of stilbene synthase, which is an enzyme involved in the synthesis of phytoalexins, was observed in leaves of Muscat blanc. It was shown that pre-treatment of grape leaves with natural symbioteS. cerevisiaeenhanced the immune response of the resistant cultivar Vostorg and inducted phytoalexins synthesis in the susceptible cultivar Muscat blanc.

Using Response Surface Methodology to Model the Clarifying Process of Muscat blanc Must for the Production of a Sweet Sparkling Wine

This study optimized clarifying Muscat blanc must with either Ca- or Na- bentonite and related mixes in a dose range of 10÷100 g/hL through a central composite design. Response surface methodology (RSM) estimated the combined effect of the bentonite type and dose on free (i.e., aglycons) and glycosylated aroma compounds. Heat stability, turbidity, and color were further analyzed. Results indicate that Na-prevalent bentonite mixes significantly reduced the must haziness, while mixes with 50% Ca-bentonite or higher led to negligible decreases. The surface plots from RSM predicted that aglycons of aroma compounds were removed by Na-bentonite at lower doses and by Ca-bentonite regardless of the dose. Further, the model estimated the removal of glycosylated aroma compounds, especially by Ca-prevalent bentonite at 50 g/hL. Despite the study’s experimental limitations, these outcomes will help the enological sector improve aromatic sparkling wine production.

Phenological and aerobiological study of vineyards in the Montilla-Moriles PDO area, Cordoba, southern Spain

AbstractPhenological and aerobiological research into major crops is of great value in adapting traditional processes to the new conditions prompted by global climate change. Data on flowering phenology and airborne pollen have also proved useful for harvest forecasting purposes. The current paper reports on an agrometeorological study carried out in the Montilla-Moriles Protected Designation of Origin area (Córdoba, southern Spain) in 2015 and 2016. The study focused on four grape cultivars produced at seven local vineyards (Pedro Ximénez, the most widely grown in the area; Verdejo; Muscat blanc à petits grains; and Chardonnay, which has been recently introduced). Phenological observations were performed on a weekly basis using the Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie scale adapted for grapevine. Airborne pollen concentrations were monitored using one Hirst-type volumetric sampler and seven passive samplers. Airborne pollen was mainly detected in vineyards during inflorescence emergence and flowering. Year-on-year differences in climatic conditions led to differences in airborne pollen levels. The main variables affecting pollen concentrations were dew point and temperature. The life-cycles recorded here were shorter than in temperate climates but longer than in tropical climates. In terms of flowering period, the cultivars studied here were classed as ‘early cultivars’. Data obtained using local passive samplers located directly in the vineyard confirmed that the airborne pollen concentrations recorded by the volumetric sampler were representative of the study area.

Examination of molecular mechanism for the color mutation in Chinese wild grapevine (Vitis davidii)

The Chinese wild grapevine, Vitis davidii, is disease resistant, matures late, and is the only Vitis species with white-fruit type native to China, and is ideal for grape breeding programs. To uncover the molecular mechanisms responsible for the V. davidii white-fruit phenotype and the relationship between accessions with white and pigmented fruits, the SSR markers, DNA sequencing and qRT-PCR were used. We found a high coefficient of genetic similarity between the two phenotypes; 12 markers, in particular, revealed that the white-skinned V. davidii “Baiciputao” evolved from the pigmented “Hunanci”. The MybA1 gene sequence analysis results revealed that “Baiciputao” harbored only MybA1a at the MybA1 locus, and in “Hunanci”, both MybA1a and MybA1c alleles were detected. This was also linked to grape skin color of the control cultivars, which were Pinot blanc and Pinot noir, Muscat blanc and Muscat rouge. To verify our conclusions, the elementary composition of the anthocyanin profiles of V. davidii and V. vinifera were analyzed using high-performance liquid chromatography and electrospray ionization mass spectrometry (HPLC–ESI–MS/MS), revealing divergent chemical profiles. The main cyanidin derivative in V. davidii was 3-O-glucoside-5-O-glucoside, whereas it was 3-O-glucoside in V. vinifera. The qRT-PCR results indicated that the total anthocyanin content in V. davidii grape skins was not solely determined by UFGT or MYB-related expression levels. These data support the conclusion that the molecular mechanism leading to the white-skinned V. davidii phenotype is the MybA1 gene mutation.

Monoterpenyl Glycosyltransferases Differentially Contribute to Production of Monoterpenyl Glycosides in Two Aromatic Vitis vinifera Varieties.

HIGHLIGHTS A similar trend on accumulation of glycosidically bound monoterpenes was observed in both varietiesTwo VvGT7 alleles mutations occurred at key sites in Muscat blanc à PetitVvGT14 exerted a major role in production of monoterpenyl glycosides in both varietiesTerpenoids are the major aroma components and generally exist as both free and glycosidically-bound forms, of which nonvolatile glycosides account for a large fraction in grape berries. Our previous study has indicated that differential accumulation of monoterpenyl glycosides in Vitis vinifera “Muscat blanc à Petit” between two regions is closely correlated to monoterpenyl glucosyltransferase (VvGT14, XM_002285734.2) transcript abundance. However, it has not been determined yet whether this correlation also exists in other Vitis vinifera varieties. This study investigated the evolution of free and glycosidically bound monoterpenes in two Vitis vinifera variety “Muscat blanc à Petit” and “Gewurztraminer” under two vintages, and further assessed the relation between the accumulation of bound monoterpenes and two monoterpenyl glycosyltransferase transcript levels. Results showed that free monoterpenes exhibited three evolution patterns in both varieties during berry development of two vintages, whereas glycosidically bound monoterpenes showed a concentration elevation with berry maturation. The Cis-rose oxide and geraniol were major components contributing to the aroma odors of “Gewürztraminer” grapes while linalool was major aroma contributor to the “Muscat blanc à Petit grain” grapes. The accumulation of glycosidically bound monoterpenes in both varieties was accompanied with the high expression of VvGT7 (XM_002276510.2) and VvGT14. Only one allele of VvGT7 was found in the variety “Gewürztraminer” and no mutation was observed in its enzyme active sites. XB-VvGT7-4 and XB-VvGT7-5 were two alleles of VvGT7 detected in “Muscat blanc à Petit grain.” The mutation on its enzyme active site inhibited the activity of XB-VvGT7-4, whereas VvGT7-5 exhibited an alteration on enzyme activity due to the insertion mutation at the position 443. Only one VvGT14 allele was found in both varieties, and the VvGT14 allele in both varieties showed the similarity on amino acid sequence. No mutation occurred in active sites of VvGT14 allele. These indicated that VvGT7 and VvGT14 differentially contributed to the production of monoterpenyl glycosides in these Vitis Vinifera varieties.

Evolution of free and bound volatile aroma compounds and phenols during fermentation of Muscat blanc grape juice with and without skins

Recently, various technologies which utilise fermentation with skins have been developed for obtaining distinct white wines. This study first reports the dynamic changes of volatiles and phenols that occur during skin fermentation in white winemaking. Volatiles were analysed by solid-phase extraction (SPE), solid-phase microextraction (SPME) and gas chromatography (GC), and phenols by ultra-performance liquid chromatography (UPLC), both with mass spectrometric detection. Monoterpenols increased during the first 3days of skin fermentation, after which certain glycosides decreased, but were higher than in control. The presence of skins reduced ho-trienol, β-damascenone, acids and esters. After a 1–3days lag phase, skin fermentation caused a constant increase of most phenols. It was estimated that skin fermentation up to 1–3days might be beneficial for monoterpenol varietal aroma, which should be re-evaluated through further studies. Longer durations promoted phenol extraction more strongly, which is possibly suitable for obtaining more distinct wines or blending components.

Evaluation of Muscat types and clones for the local market

Ten European clones and selections of 'Muscat blanc' were investigated about their variability in genetic and enological behavior. The SSR profile of about 120 loci allowed to differentiate most of them. Nevertheless the differences within the variety are rare and do not reflect the heterogeneity of observed variability. One of the clones (B41/5) represents an earlier ripening type where the overall quality was independent from sugar content. A 27-1 clone was one of the clones with steady high rating concerning wine quality. An interesting alternative for early ripening areas could be the late ripening 'Goldmuskateller' due to the higher stability against Botrytis. One of the samples was not true to type and represented this cultivar.

First Report of Grapevine Pinot gris virus Infecting Grapevine in Slovenia.

Unusual virus-like symptoms were first observed in 2001 on grapevine cvs. Pinot gris and Sauvignonasse in vineyards from the western part of Slovenia. Symptomatic plants showed shortened internodes, poor leaf development, mottling, and deformations of leaves that resulted in poor growth of symptomatic plants. In 2003 and 2004, several samples were tested for Arabis mosaic virus, Cherry leafroll virus, Grapevine fanleaf virus, Raspberry bushy dwarf virus, Strawberry latent ringspot virus, Tomato black ring virus, Tomato ringspot virus, and Tobacco ringspot virus by DAS-ELISA, but none of them could be confirmed as the cause of the observed symptoms. During intensive visual inspections between 2002 and 2006, the symptoms were observed on most grapevine cultivars grown in the Primorska region but predominantly on the two previously mentioned cultivars. In Trentino, northern Italy, similar virus-like symptoms, i.e., chlorotic mottling, puckering and deformation of the leaves, reduced yield, and low quality of the berries were observed in grapevine plants cv. Pinot gris in 2003 and in cvs. Traminer and Pinot noir in 2009 (2). No common grapevine viruses could be associated with the disease. In 2012, a new trichovirus named Grapevine Pinot gris virus (GPGV) was found in Pinot gris plants using deep sequencing. The virus was also detected in symptomless plants (2). GPGV was later reported also from Korea causing inner necrosis of berries and poor fruit set in grapevine cv. Tamnara (1). In 2012, 42 leaf samples from mostly symptomatic grapevine plants of cvs. Pinot gris, Pinot noir, and Muscat blanc were collected at three locations in the Primorska region. Total RNA was extracted from leaves using the MagMAX Express magnetic particle processor with MagMAX-96 Total RNA Isolation Kit and Plant RNA Isolation Aid in Lysis Binding Solution Concentrate (all by Life Technologies, Grand Island, NY). DNA fragments of 1,049 bp corresponding to the movement protein gene were successfully amplified by RT-PCR from 40 samples using primers GPgV5619 and GPgV6668 (2). Amplification products from three plants were cloned into the pGEM-T Easy vector (Promega, Madison, WI) and sequenced. The sequences were deposited in the EBI database under the accession numbers HG738850 to 52. All the nucleotide sequences shared 97.4 to 97.6% identity with GPGV from Italy (sequence FR877530) and 97.1 to 98.2% amino acid identity within the translated region. To our knowledge, this is the first report of GPGV in Slovenia. The disease seems to be spreading extensively in the Primorska region, causing considerable economic losses, and in 2013 it was also observed in other regions of Slovenia. Since the virus could be found in symptomless plants in Italy and in Slovenia, its role in the development of the disease should be further investigated.

Antioxidant capacity, total phenolic, carotenoid, and vitamin C contents of five table grape varieties from Algeria and their correlations

<p style="text-align: justify;"><strong>Aim</strong>: The aim of this work was the determination of some antioxidants (total polyphenols (TPP), total flavonoids (TF), carotenoids, vitamin C, the antioxidant capacity (AC) (reducing power) and other physicochemical parameters, such as pH, total soluble solids (°Brix), total acidity and density, in an attempt to understand how the evaluated characteristics vary with different grape varieties.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Grape is currently known as a fruit that presents a very high antioxidant activity that can inhibit the harmful effects of free radicals. In this study, five Algerian table grape varieties were tested : Cardinal, Gros noir, Muscat noir, Muscat blanc and Victoria. TPP, TF, carotenoids and AC were determined by using colorimetric assays, and the physicochemical parameters (pH, °Brix, total acidity and density) were measured using classical methods. The darker varieties (Gros noir and Muscat noir) had the highest levels of polyphenols, flavonoids, carotenoids and vitamin C and possessed a good reducing power. A strong positive correlation was found, especially between TPP, TF and AC.</p><p style="text-align: justify;"><strong>Conclusion</strong>: This study indicated that some Algerian grape varieties exhibit high antioxidant phenolic and carotenoid content, which can potentially be used as natural source of antioxidant.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This study on the AC, the TPP, carotenoid and vitamin C contents of five table grape varieties from Algeria and their correlations is very unique, as it is the first study on varieties grown in this country.</p>

Dynamic study of yeast species and Saccharomyces cerevisiae strains during the spontaneous fermentations of Muscat blanc in Jingyang, China

The evolution of yeast species and Saccharomyces cerevisiae genotypes during spontaneous fermentations of Muscat blanc planted in 1957 in Jingyang region of China was followed in this study. Using a combination of colony morphology on Wallerstein Nutrient (WLN) medium, sequence analysis of the 26S rDNA D1/D2 domain and 5.8S-ITS-RFLP analysis, a total of 686 isolates were identified at the species level. The six species identified were S. cerevisiae, Hanseniaspora uvarum, Hanseniaspora opuntiae, Issatchenkia terricola, Pichia kudriavzevii (Issatchenkia orientalis) and Trichosporon coremiiforme. This is the first report of T. coremiiforme as an inhabitant of grape must. Three new colony morphologies on WLN medium and one new 5.8S-ITS-RFLP profile are described. Species of non-Saccharomyces, predominantly H. opuntiae, were found in early stages of fermentation. Subsequently, S. cerevisiae prevailed followed by large numbers of P. kudriavzevii that dominated at the end of fermentations. Six native genotypes of S. cerevisiae were determined by interdelta sequence analysis. Genotypes III and IV were predominant. As a first step in exploring untapped yeast resources of the region, this study is important for monitoring the yeast ecology in native fermentations and screening indigenous yeasts that will produce wines with regional characteristics.

2-Methoxy-3-isobutylpyrazine in grape berries and its dependence on genotype

2-Methoxy-3-isobutylpyrazine (MIBP) contributes a bell pepper aroma to many grape cultivars and has a reported aroma threshold of ∼2 ng L −1 in water. The purpose of this study was twofold: (1) develop a procedure using headspace solid phase micro-extraction combined with GC–MS in the selected ion monitoring mode (HS-SPME-GC–MS-SIM) for analysis of MIBP in grape berries, and (2) determine the location of MIBP biosynthesis in grapevines by approach grafting clusters of Vitis vinifera L. cvs Cabernet Sauvignon and Muscat blanc onto each other. The soluble solids and pH of the grape juice/homogenate matrix from different grape berry developmental stages influenced the method precision; therefore, quantification via the method of standard addition was used. Using our developed method, the limit of detection (LOD) and limit of quantitation (LOQ) of MIBP were 0.1 ng L −1 and 2 ng L −1, respectively, measured in a model juice and non-MIBP containing Chardonnay juice. Spiked recoveries averaged between 91% and 112% in Cabernet Sauvignon and Pinot noir homogenates and the overall relative standard deviation was less than 10%. The method was used to analyze MIBP in 29 grape cultivars and in fruit from clusters grafted to Cabernet Sauvignon or Muscat vines. Quantifiable levels were found only in Cabernet franc, Cabernet Sauvignon, Merlot, Sauvignon blanc and Semillon, providing information on the genetic connection for the occurrence of MIBP in grapes. No MIBP was detected in the berries of Muscat blanc clusters grafted onto Cabernet Sauvignon vines when sampled at fruit maturity. MIBP was detected in all berries of Cabernet Sauvignon regardless the graft configuration. The data indicate that MIBP or its precursors originate in the berry and its formation depends upon grape genotype.

The SSR-based molecular profile of 1005 grapevine (Vitis vinifera L.) accessions uncovers new synonymy and parentages, and reveals a large admixture amongst varieties of different geographic origin

A collection of 1005 grapevine accessions was genotyped at 34 microsatellite loci (SSR) with the aim of analysing genetic diversity and exploring parentages. The comparison of molecular profiles revealed 200 groups of synonymy. The removal of perfect synonyms reduced the database to 745 unique genotypes, on which population genetic parameters were calculated. The analysis of kinship uncovered 74 complete pedigrees, with both parents identified. Many of these parentages were not previously known and are of considerable historical interest, e.g. Chenin blanc (Sauvignon×Traminer rot), Covè (Harslevelu selfed), Incrocio Manzoni 2-14 and 2-15 (Cabernet franc×Prosecco), Lagrein (Schiava gentile×Teroldego), Malvasia nera of Bolzano (Perera×Schiava gentile), Manzoni moscato (Raboso veronese×Moscato d'Amburgo), Moscato violetto (Moscato bianco×Duraguzza), Muscat of Alexandria (Muscat blanc à petit grain×Axina de tres bias) and others. Statistical robustness of unexpected pedigrees was reinforced with the analysis of an additional 7-30 SSRs. Grouping the accessions by profile resulted in a weak correlation with their geographical origin and/or current area of cultivation, revealing a large admixture of local varieties with those most widely cultivated, as a result of ancient commerce and population flow. The SSRs with tri- to penta-nucleotide repeats adopted for the present study showed a great capacity for discriminating amongst accessions, with probabilities of identity by chance as low as 1.45×10(-27) and 9.35×10(-12) for unrelated and full sib individuals, respectively. A database of allele frequencies and SSR profiles of 32 reference cultivars are provided.

Genetics and Ampelography Trace the Origin of Muscat fleur d’oranger

Examination of molecular profiles of grape cultivars, including some with aromatic flavor, has identified the pedigree of Muscat fleur d’oranger (or Orange muscat) as the descendant of two historical and important European grape varieties. This grape with muscat flavor and a particular note of orange blossom was apparently derived from a cross between Chasselas and Muscat à petits grains blancs (Muscat blanc). This hypothesis is supported by genetic, morphological, and historical evidence.

Impact of Microorganism Priming on Oxidative Processes and the Antioxidant Defense System of Grapes Infected with Downy Mildew

Priming plants with natural agents, including microorganisms, is a promising alternative to chemical methods of protection in growing plants and, particularly, in viticulture. However, the molecular mechanisms of the priming phenomenon are still not fully elucidated. The antioxidant system and reactive oxygen species are known to effectively modulate plant responses to various external influences. This study aimed to identify the relationship between the priming of grapes by microorganisms and the functioning of the antioxidant system in a protective response to downy mildew infection. The experiment was carried out on leaf discs of Muscat blanc susceptible to downy mildew infected with Plasmopara viticola and treated with microorganisms incompatible with the pathogen, as well as with the corresponding symbiotic microorganisms. During the compatible interaction between P. viticola and grapes, oxidative processes were suppressed with viniferin formation. Leaf treatments with Saccharomyces cerevisiae and Bacillus subtilis effectively curbed the development of downy mildew on grape leaves. Priming with these microorganisms did not lead to a significant change in the biochemical parameters of grapes. Nevertheless, subsequent downy mildew infection initiated the formation of viniferin and maintained H2O2 content at a high level. Thus, priming with microorganisms eliminates the physiological effects of compatible interactions between downy mildew and grapes associated with blocking oxidative processes. To suppress pathogen development, host defenses and antagonistic effects of microbial priming agents are required

Toward the authentication of varietal wines by the analysis of grape (Vitis vinifera L.) residual DNA in must and wine using microsatellite markers.

In an attempt to develop a technique for the identification of grape cultivars in commercial wines, a method for the extraction of DNA from must and experimental wines was adapted and optimal PCR conditions for the amplification of this DNA were established. DNA was analyzed during the fermentation process for six cultivars (Chardonnay, Clairette blanche, Grenache noir, Merlot, Muscat blanc à petits grains, and Syrah). The extractions were performed on solid parts in suspension as well as on the aqueous fraction. Expected profiles for these cultivars were obtained with DNA extracted from the solid parts during all of the fermentation process and for the wine. The analysis of DNA extracted from aqueous fractions was less reproducible, and microsatellite amplifications were obtained only in the case of Clairette blanche, Merlot, and Syrah wines. Results demonstrate that the purification process is adequate for the analysis but that the DNA concentration represents the main limiting factor. Technical improvements of the method are discussed.

Field Response ofVitis viniferaCultivars to Methanol

The response of <i>Vitis vinifera</i> cultivars to methanol was investigated at the Orchard Mesa Research Center in Grand Junction, Colorado. Sublethal methanol doses, based on visual observations, were 90% for leaves and 100% for trunks. The accumulation of total soluble solids (TSS) in berries was also monitored weekly until harvest. There was no significant difference between the treated and control vines during the period of study, with the exception of Muscat blanc, which showed a slightly higher TSS content in methanol-sprayed vines than in controls. This difference, however, disappeared during ripening. There was no significant effect of methanol on photosynthesis, transpiration, nor stomatal resistance. At harvest, data on yields estimated by cluster weight, berry weight and berry size indicated no differences between the two treatments. Methanol did not alter cold hardiness of dormant buds, measured by differential thermal analysis. It was concluded that in this study methanol had little or no physiological, nor practical effect on grapes.