Characterization of wines from grape varieties through multivariate statistical analysis of H NMR spectroscopic data

¹H NMR spectroscopic analysis coupled with multivariate statistical data was used to characterize wines vinified from four grape varieties: Muscat Bailey A (Vitis labrusca), Campbell Early (V. labrusca B.), Kyoho (V. labrusca L.) and Meoru (Vitis coignetiae). Pattern recognition methods, such as principal component analysis (PCA) and orthogonal projection to latent structure discriminant analysis (OPLS-DA), showed clear differentiation between wines made from these grape varieties. Metabolites responsible for the differentiation were identified as 2,3-butanediol, glycerol, malate, citrate, tartrate, succinate, lactate, proline, alanine, choline and trigonelline. The PCA score plot of quantitative analysis of targeted profiling data also showed clear separation between the wines. The highest levels of glycerol, 2,3-butanediol, succinate and alcohol were found in Kyoho wines, suggesting higher sugar content in the Kyoho grape berry compared to other grape varieties. Higher contents of citrate and trigonelline in Muscat Bailey A wines, alanine in Campbell Early wines and proline, malate and choline in Meoru wines demonstrated that the metabolites of the wines vary with the grape variety. This study provides insight into the relationship between grape variety and its wine through global and targeted analysis of ¹H NMR spectral data.     

EFFECT OF A DEFICIT IRRIGATION REGIME ON THE QUALITY OF WINES MADE FROM WHITE GRAPES (VITIS VINIFERA L.) GROWN IN SEMIARID AREAS

ABSTRACT

The dependence of wine quality on the irrigation management strategies in Vitis vinifera L. was tested from 1999 to 2002. A drip‐irrigation experiment was performed on white grapes of the cultivars Baladí, Airén, Montepila, Muscat Blanc à Petits Grains and Pedro Ximénez, grafted and vineyard‐planted in 1995 in Cabra (Cordoba, Spain). Treatments consisted of a nonirrigated control and an experimental deficit irrigation, in which water was applied from fruit set until near harvest. A total of 19 analytical parameters were measured, including alcohols, total phenol content and optical density as well as ethanol, pH, total acidity and dry extract. Wines were evaluated for their visual characteristics, aroma, taste and finish. The irrigation treatment contributed to a higher dry extract, and an increase in malic acid and potassium in wines. There was a decrease in pH, isobutanol and isoamyl alcohols with increasing water application. Sensory evaluation ranked irrigated over nonirrigated wines with the only exception of the wines of Muscat Blanc à Petits Grains. The main defects of nonirrigated wines were attributed to visual characteristics and poorer taste quality.

PRACTICAL APPLICATIONS

Proper irrigation management, i.e., optimizing both the timing and the amount of water supplied, plays a significant role in wine quality and is especially important in arid and semiarid areas. The aim of this study was to ascertain the effect of irrigation in wine quality. In this study, irrigation was applied only during periods in which water stress might affect production and harvest quality. The chemical results ranked irrigated over nonirrigated wines and Muscat Blanc à Petits Grains over other cultivars, regarding their quality. Sensory evaluation ranked irrigated over nonirrigated wines with the only exception of the wines of Muscat Blanc à Petits Grains. Therefore, deficit irrigation during berry development and ripening appears to be a promising technique for the production of quality young wines in semiarid achieving a compromise between aroma and taste quality.     

Time course of the colour of young red wines from Vitis vinifera L. during ageing in bottle

The colour characteristics of red wines from Vitis vinifera L. cv Tempranillo, Graciano and Cabernet Sauvignon (vintage 2000) from Navarra (Spain), was studied during 26 months of ageing in bottle through the evaluation of the wine visible spectrum and of several colorimetric indices (colour intensity, %red, %yellow, %blue, %dA and tint) and CIELAB variables (L*, C*, h, a* and b*). During ageing in bottle, the spectrum of Tempranillo wine (pH 4.3) mainly changed in the absorbance range between 420 and 500 nm, whereas Graciano (pH 3.5) and Cabernet Sauvignon (pH 3.6) wines registered a decrease in absorbance in the interval between 500 and 560 nm. The time course of the different wine colour parameters was found to fit either a second‐order polynomium or a linear model, depending on the grape variety employed. CIELAB variables could be described in terms of their colorimetric index counterparts, showing b* and h relative greater errors. Although the wine total chromatic changes in CIELAB units registered after 26 months of ageing in bottle indicated changes perceivable by the human eye (ΔE* ≥ 2.7) for the three varieties studied, Graciano and Cabernet Sauvignon wines showed a more balanced colour evolution than Tempranillo wine.     

Yeast and bacterial modulation of wine aroma and flavour

Wine is a highly complex mixture of compounds which largely define its appearance, aroma, flavour and mouth‐feel properties. The compounds responsible for those attributes have been derived in turn from three major sources, viz. grapes, microbes and, when used, wood (most commonly, oak). The grape‐derived compounds provide varietal distinction in addition to giving wine its basic structure. Thus, the floral monoterpenes largely define Muscat‐related wines and the fruity volatile thiols define Sauvignon‐related wines; the grape acids and tannins, together with alcohol, contribute the palate and mouth‐feel properties. Yeast fermentation of sugars not only produces ethanol and carbon dioxide but a range of minor but sensorially important volatile metabolites which gives wine its vinous character. These volatile metabolites, which comprise esters, higher alcohols, carbonyls, volatile fatty acids and sulfur compounds, are derived from sugar and amino acid metabolism. The malolactic fermentation, when needed, not only provides deacidification, but can enhance the flavour profile. The aroma and flavour profile of wine is the result of an almost infinite number of variations in production, whether in the vineyard or the winery. In addition to the obvious, such as the grapes selected, the winemaker employs a variety of techniques and tools to produce wines with specific flavour profiles. One of these tools is the choice of microorganism to conduct fermentation. During alcoholic fermentation, the wine yeast Saccharomyces cerevisiae brings forth the major changes between grape must and wine: modifying aroma, flavour, mouth‐feel, colour and chemical complexity. The wine bacterium Oenococcus oeni adds its contribution to wines that undergo malolactic fermentation. Thus flavour‐active yeasts and bacterial strains can produce desirable sensory results by helping to extract compounds from the solids in grape must, by modifying grape‐derived molecules and by producing flavour‐active metabolites. This article reviews some of the most important flavour compounds found in wine, and their microbiological origin.     

Sensory and chemical characteristics of trans‐resveratrol‐fortified wine

Background and Aims: trans‐Resveratrol (tR) is a grape‐derived polyphenolic that is believed to confer considerable health benefits to humans. Its concentration in wine, however, is highly variable, and thus direct fortification of wine with tR has been proposed to create a high‐value, health‐promoting wine product. This study determines the sensory and chemical characteristics of tR fortified white and red wine. Methods and Results: Riesling and Cabernet Sauvignon wines were enriched with 20 mg/L and 200 mg/L tR. Basic chemical and sensory indicators of wine quality, trans‐ and cis‐resveratrol concentrations, and antioxidant capacity were assessed at bottling and at 6, 18, 31, 44 and 58 weeks post‐bottling. tR concentrations in bottled wine remained relatively stable throughout the 58‐week period of this study. In addition, tR‐enriched wines had a significantly higher antioxidant capacity compared with control wine, and Cabernet Sauvignon fortified at both tR concentrations had greater colour intensity. Basic chemical indicators of wine quality were not affected by tR fortification, and sensory changes were minimal, with higher bitterness intensity in Riesling fortified at 200 mg/L tR the most consistent finding. Conclusions: tR is relatively stable in wine during bottle aging, and tR enrichment up to 200 mg/L results in minimal change to wine quality, particularly with red wine. Significance of Study: This is the first study to investigate the chemical and sensory characteristics of tR‐enriched wines. Results indicate that these products may have considerable potential for the functional food market.     

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

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

Quantification of DNA during winemaking by fluorimetry and <Emphasis Type="Italic">Vitis vinifera</Emphasis> L.-specific quantitative PCR

The ability to genotype wine would be of a great benefit to control the varietal wine authenticity. In this paper, we assessed the fate of grapevine DNA and total DNA during vinification to suggest the latest sampling point that would allow genotyping. The total DNA concentration was measured by fluorimetry and the specific Vitis vinifera L. DNA concentration was measured by quantitative PCR in samples obtained from different steps of vinifications of four wines. To elucidate the effect of pre-extraction and extraction steps on DNA yield from wine, several samples from bottle of wine, two precipitation salts, and two DNA extraction solutions were tested. It was found that hundreds of genome equivalents of grapevine DNA can be extracted from every winemaking sample and from wine. In tested samples, differences in DNA yield among wines from different grapevine varieties, differences among extraction methods, and sampling variation in wine were not statistically significant.     

Anthocyanin composition and content in grape berry skin in Vitis germplasm

The composition and content of anthocyanins were surveyed by HPLC–MS for assessing genotypic variation in berry skin of 110 grape cultivars, including 3 species and 5 interspecific hybrids. Twenty-nine anthocyanins were identified. For total anthocyanin content, Vitis vinifera and hybrids of Vitis labrusca and V. vinifera were low, and in general, wild species and rootstock were higher than interspecific hybrids, and wine grapes were higher than table grapes in the same species. As regards the composition of anthocyanins, malvidin-derivatives were the most abundant anthocyanins in the majority of germplasms. All anthocyanins were monoglucoside derivatives in V. vinifera, but all the other Vitis germplasms had both mono- and di-glucoside derivatives. Moreover, peonidin-derivatives and malvidin 3-O-glucoside were, respectively, main anthocyanins in table and wine grapes of V. vinifera. Via principal component analysis, the distribution of the cultivars in a scatter plot depended upon their total anthocyanins content, mono- and di-glucoside derivatives.     

Volatile secondary metabolites of Greco (Vitis vinifera L.) must

Greco grape (Vitis vinifera L.), a typical white variety of Campania region in the South of Italy, was investigated for the first time determining volatile‐free and glycosidically bound secondary metabolites that could be at the base of the aroma profile of DOCG ‘Greco di Tufo’ wines. C₁₈ reversed‐phase isolates of ‘Greco’ musts have been investigated by gas chromatography/mass spectrometry. ‘Greco’ must resulted characterised by a content of glycoconjugated terpenoids ranging from 180 to 370 μg L^?1. Linalool and geraniol detected in the ‘Greco’ must above their odour thresholds could explain a floral character attributed to the wine. Guaiacol in free fraction, 4‐vinylguaiacol and eugenol in the bound fraction could be at the origin of nutty and spicy notes of the wine. Some observations of this study also show that precursors of floral, spicy and nutty odorants seem to be enhanced by clay soil and good sun exposure.     

Characterization of Polish Wines Produced from the Multispecies Hybrid and Vitis vinifera L. Grapes

Phenolic profile, antioxidant activity, and color parameters of Polish wines, produced from the multispecies hybrid and Vitis vinifera L. grapes were analyzed. A principal component analysis was applied, in order to differentiate the investigated wines in terms of content of phenolic compounds. The white wines turned out to be similar to each other in terms of color parameters and the results of principal component analysis, while the red wines strongly differed in this respect. However, the white wine produced from the multispecies hybrid grapes contained a higher level of phenolic acids and flavonoids, as compared to the white wines obtained from the hybrid cultivars. Out of the red wines, Rondo wine, produced from the multispecies hybrid grapevine was the richest in total phenolic and phenolic acids content. Caffeic acid and quercetin were the predominant phenolics in majority of the wines tested.     

Flavonol composition of Australian red and white wines determined by high‐performance liquid chromatography

Background and Aims: Flavonols are present in Vitis vinifera L. wine grapes as glycosides and are found in wines in both their glycosidic and aglycone forms. Flavonols and their glycosides are important components in wine because of their impact on colour, taste and health properties. An assessment of the flavonols and flavonol glycosides present in a wide selection of Australian red and white wines (n = 121 and 44, respectively) was undertaken. Methods and Results: Analyses were performed using HPLC, with compound identification being aided by HPLC‐MS. In the red wines, quercetin and myricetin dominated the flavonol profile, and quercetin‐3‐glucuronide was by far the most abundant glycoside present. White wines had considerably lower levels of flavonols and their glycosides, in most cases, being below the detection limit of the HPLC method. Conclusions: There appeared to be no correlation between the flavonol profile and wine variety or region in either white or red wines. Contrary to literature reports of rutin in wine, rutin was not found in any of the wines we analysed, and spiking experiments showed rutin rapidly degraded to the aglycone quercetin. Furthermore, changes in elution order for some quercetin glycoside standards were observed depending upon the acid used in the mobile phase. Significance of the Study: This is the first time the flavonol contents of an extensive cross section of Australian wines have been reported. The concentrations are consistent with those reported in wines from other countries. In light of the instability of rutin in wine, critical review should be given to reports discussing its presence.     

Characterization of red wines from South America based on sensory properties and antioxidant activity

BACKGROUND: It is widely accepted that red wines constitute one of the most important sources of dietary polyphenolic antioxidants. However, it is still not known how some variables such as variety, vintage, country of origin, and retail price are associated with the antioxidant activity and sensory profile of South American red wines. In this regard, 80 samples produced in Brazil, Chile and Argentina were assessed in relation to their sensory properties, color and in vitro antioxidant activity, and results were subjected to multivariate statistical techniques. RESULTS: Samples were grouped in clusters, characterized by high, intermediate and low in vitro antioxidant activity, sensory properties and prices. It was possible to observe that wines with high antioxidant activity were associated to high retail prices and overall perception of sensory quality. CONCLUSION: South American wines produced from Vitis vinifera such as Syrah, Malbec and Cabernet Sauvignon had higher in vitro antioxidant activity and also higher sensory quality than wines produced from Vitis labrusca. This result was independent of vintage (2002‐2010), corroborating the idea that the same grape varietal, even when produced in different years, displays similar sensory characteristics and antioxidant activity. Copyright © 2011 Society of Chemical Industry     

Component analysis and sensory evaluation of Korean black raspberry (Rubus coreanus Mique) wines

Three types of Korean black raspberry wines were made from juice, juice‐pulp and juice‐pulp‐seed. Changes in the physicochemical properties and key compounds of the wines during fermentation were determined. The colour intensity was weakened with a 50% decrease in the anthocyanin content, but the colour intensity was strengthened by supplementation with pulp and seeds. Citric acid was the major organic acid (approximately 90%) of the wines, and the amino acid content was lowered to less than 10% by fermentation. The total volatile compound content was increased 5.3 times and nine new compounds were identified. The major components of the wines were isobutanol, n‐propanol and isoamyl acetate. The juice‐pulp‐seed wine contained the highest contents of anthocyanin, polyphenols and proanthocyanin. The anti‐oxidative activity of wines increased with an increasing content of polyphenols. The content of proanthocyanidin, a compound for pucker and bitter tastes, was approximately two to three times greater than in commercial grape wines. In a sensory test, the highest scores for colour, flavour, taste and overall acceptance were awarded to the juice‐pulp‐seed wine.     

Freeze-dried grape skins by-products to enhance the quality of white wines from neutral grape varieties

Wastes generated by the wine industry (grape marc), mainly residues from white wine vinifications, are an important source of aroma and phenolic compounds. However, grape marcs are highly perishable and seasonal products, so they require an adequate conservation method. In this respect, freeze-drying, versus conventional drying methods, is a good alternative since this technique preserves the quality of the raw material. Specifically, freeze-drying hardly caused losses of characteristic grape variety volatiles, such as terpenes and C₆ compounds, neither increases in the concentration of furan compounds. Furthermore, freeze-dried grape skins obtained from residues did not presented changes in the amounts of phenolic compounds with respect to the fresh skins. On the other hand, skin-contact treatment with Muscat freeze-dried skins enhanced the aroma of white wines made from Airén grapes, a variety considered neutral, without affecting negatively their color. Skin-contact treatment preserved the wine fruity notes, although the only wine that conserved floral notes in its flavor profile was that macerated with freeze-dried skins. Also, these wines were better rated by the assessors than those macerated with Muscat fresh skins.     

Impact of maceration time on colour‐related phenolics,sensory characteristics and volatile composition of mulberry wine

This study investigated the effect of maceration treatment on colour‐related phenolics, sensory characteristics and volatile composition in mulberry wine. Pre‐fermentation maceration was performed for 2 days (‘short’), 6 days (‘medium’) and 8 days (‘long’), respectively, followed by the same fermentation process. Results showed that the long maceration (LM) caused higher level of anthocyanins in wine, especially cyaniding‐3‐O‐rutinoside, cyaniding‐3‐O‐glucoside and dephinidin‐3‐O‐glucoside, whereas the short maceration caused lower level of phenolic acids in wine. The medium maceration (MM) wine showed the highest level of flavonols but the lowest concentration of flavan‐3‐ol. The LM wine exhibited greater red tone and colour intensity accompanied by higher amounts of free and copigmented anthocyanins. The LM wine showed lower levels of alcohols, acids, terpenoids, benzenes and sulphur compounds, whereas the lowest level of esters was found in the MM wine. The LM wine had reduced fruity and floral aroma and overall flavour complexity compared with the other wines. Copyright © 2018 The Institute of Brewing & Distilling     

The influence of skin contact during alcoholic fermentation on the aroma composition of Ribolla Gialla and Malvasia Istriana Vitis vinifera (L.) grape wines

Grapes from the Vitis vinifera (L.) varieties Ribolla Gialla and Malvasia Istriana were subjected to two skin contact procedures: pomace maceration and whole berry maceration during alcoholic fermentation. Wine free volatile compounds were determined using two extraction techniques coupled to GC; odour activity values were calculated and compared to control wines without skin contact. The highest concentrations of esters and relative fruity impacts were determined in the control wines for both varieties. Pomace maceration was found to be an effective procedure for the extraction of varietal aroma compounds like terpenes, but only in the Malvasia Istriana was their higher impact on floral odour determined. Pomace maceration resulted in higher total phenol and methanol content. Whole berry maceration was less efficient in terpene extraction, and its impact on general wine composition was not so radical. Control wines were chosen as preferred wines for odour and overall impression.