White Table Wines Research Articles

INFLUENCE OF MODERN STABILIZATION METHODS ON QUALITY VARIETAL WHITE WINES FROM UKRAINIAN BREEDING GRAPE

Modern winemaking in Ukraine is being significantly transformed and is actively developing. Our state has now turned to the search for its own wines and grape varieties. For international recognition, it is important to develop your case of wines that will be able to show the diversity of wine regions from Southern Bessarabia and the Northern Black Sea Coast to Transcarpathia. There are more and more small winemakers who are experimenting with new varieties, such as Sukholimansky white, Citronny Magaracha, Zagrei, Johanniter, Zvalgate, Solaris, Aromatny, Telti Kuruk and various muscat varieties. The organoleptic profile of such wines should express the varietal characteristics of local grape varieties and the agro-climatic features of the terroir. At the same time, the modern technology of white table wines should be built on the principles of maximum preservation of varietal aroma and minimization of its oxidation during the technological process. The article reflects the results of theoretical studies of literary sources regarding the mechanisms of oxidative processes of various nature in the process of grape processing; the market of modern preparations for stabilizing wine materials is considered. According to the goal, the influence of the use of the enzyme preparation Viazim clarif one on the process of clarifying the wort was investigated. The effect of complex antioxidant pasting of wort with the stepwise application of "Tanal W4", "Polygreen" and "Granula" bentonite on aromatic compounds and the formation of the aromatic profile of the finished product was also studied. At the last stage of research, the organoleptic profile of white wine materials of the studied grape varieties was determined. It was established that the general trend of stabilization processes in modern winemaking is transferred to the wort stage. According to the results of practical tests, in the form of trial pastes of wort, it is proposed to use the enzyme preparation "Viazim clarif one" at the stage of extracting wort; the effect of complex antioxidant pasting of wort with stepwise application of "Tanal W4", "Polygreen" and "Granula" bentonite was studied. Practical recommendations have been developed for winemakers on the application of antioxidant wort pasting for domestic grape varieties Sukholimansky white and Citronny Magaracha, which are now gaining popularity in Ukraine.

ПЕРСПЕКТИВНЫЕ ТЕХНИЧЕСКИЕ ФОРМЫ ВИНОГРАДА СЕЛЕКЦИИ ФГБНУ ВНИИВиВ им. Я.И. ПОТАПЕНКО ДЛЯ ПРОИЗВОДСТВА БЕЛЫХ ВИН

The results of the technological assessment of white promising technical forms of grapevine bred in Ya.I. Potapenko Institute: 10-30-4-6, 10-30-4-13, 10-30-4-17, which are pointed out by optimal sugar accumulation and suffi-cient juice yield. The research was carried out in the laboratory of winemaking technology in microwinemaking conditions. The mass of one batch of grapes was 5‒10 kg. In the wort of the studied forms, the following indicators were determined: titratable acidity, sugar con-tent, pH value, glucoacidometric index. White dry wine materials were prepared according to the classical technology. In the studied sam-ples of wines, the main physical and chemical indicators were determined. As a result of the organoleptic evaluation, conclusions were drawn about the prospects of using these forms for the production of natural white ta-ble wines.

ТЕХНОЛОГИЧЕСКАЯ ОЦЕНКА ИНТРОДУЦИРОВАННЫХ БЕЛЫХ ТЕХНИЧЕСКИХ СОРТОВ ВИНОГРАДА ДОНСКОЙ АМПЕЛОГРАФИЧЕСКОЙ КОЛЛЕКЦИИ

The results of the technological assessment of white technical grape varieties growing on the ampelographic collection of the institute are shown: Riesling, Grubella, Goruli mtsvane, No-rock, Khotsa tsibil. Samples of dry white wines were prepared using classical technology. The research was carried out in the laboratory of winemaking technology in micro-winemaking conditions. The weight of one batch of grapes was 7–15 kg. The main physical and chemical parameters of wort and wine were determined. As a result of the organoleptic assessment, con-clusions were drawn about the advisability of using these varieties for the production of natu-ral white table wines. Riesling was chosen as a control variety. Wine materials from the re-searched varieties were distinguished by their typical, pale straw color, with a greenish tint, delicate varietal aroma, full, harmonious taste. This indicates a high potential of the studied varieties for the preparation of high-quality wines.

An accurate single-step LLE method using keeper solvent for quantification of trace amounts of sotolon in Port and white table wines by HPLC-DAD

Sotolon has been reported to play an important role in the typical aroma of aged Port wines. A simple and cheap single-step liquid–liquid extraction (LLE) using glycerol as a keeper for liquid chromatography/ultra-violet absorption quantification of sotolon in Port wines is proposed in this work. The glycerol plays a protective role during the concentration of the extracts increasing the sotolon recovery as well the method repeatability. The proposed method yields chromatograms without interfering compounds and a forty-fold enrichment of sotolon. The detection and quantification limits were far below the sotolon odour threshold in Port wine (19 μg/L). The method was also validated for dry white table wines with good validation parameters. The methodology was successfully applied to selected commercial Tawny, Ruby, and White Port wines, being reported the presence of sotolon in young Ruby and White Port wines for the first time, although below the olfactory detection threshold.

IMPROVEMENT OF THE TECHNOLOGICAL MODES OF PRODUCING DRY WHITE TABLE WINES

By using the classical technology of making dry white wines, which does not involve maceration of the pomace, we can produce standard table wines, light and delicate. This minimises such an objectionable factor as saturation of the wine with extra nitrogenous and phenolic substances and oxidative enzymes. On the other hand, this scheme gives a specific varietal aroma no chance to reveal itself more expressively. The paper overviews briefly the scientific works considering the modes of pomace maceration before fermentation and the use of enzyme preparations in the technology of white table wines. The physicochemical and sensory characteristics of wine materials from Rkatsiteli grapes grown in the south of the Mykolaiv Region have been analysed. This analysis has proved that standard white table wine materials can be obtained both by the traditional method (the so called ‘white’ method) and with the use of short-term maceration of the pomace. Macerating the pomace resulted in obtaining fuller, richer wine materials with a bright aroma and good body. It has been shown that to obtain bright and not too blunt wine materials, the most essential parameter of the maceration process is its low temperature. A pectolytic enzyme preparation used during maceration increased, to some extent, the mass concentration of phenolic substances, the reduced extract, the optical density, and the concentration of terpene alcohols. Besides, it allowed fuller revealing a wine’s aromatic profile. The research has resulted in establishing that there is regularity in how the concentration of terpene alcohols changes with different temperature conditions of steeping the pomace. It has been shown that the maximum concentration of terpenes responsible for the varietal aroma is best retained in wine materials when the maceration temperature is 5°C. A rise in the pomace maceration temperature to 20°C led to a decrease in the concentration of labile terpene alcohols, so it should be avoided in producing quality wines. Studying different maceration modes has allowed recommending a certain method to manufacture full-bodied, well-structured white table wines with a pronounced varietal aroma. This method involves adding the enzyme preparation Depectil CLARIFICATION to the pomace and macerating it for 12 hours at 5°C.

The possibility of using the potentiometric titration method to determine the antioxidant properties of wines

The results of study of phenolic composition, antioxidant activity and oxidation state of phenolic substances of white and red table wine materials were presented. Close correlational between the antioxidant activity of white table wine materials, the oxidation parameter of phenolic composition and the content of monomeric, oligomeric and polymeric forms of phenolic compounds were established., The correlation between antioxidant activity and oxidation parameter of phenolic substances has not been established for red wine materials. Direct effect of the oxidation state of phenolic substances in white table wine materials on their antioxidant activity was shown. The oxidation parameter of phenolic substances can be used as a criterion of assessing the antioxidant properties of white table wine materials and wines. The method of potentiometric titration may be recommended for use in processing, training and experimental analytical laboratories to assess the antioxidant activity of white table wine materials and wines.

Physicochemical, Sensory and Microbiological Quality of Table Wine Produced from Coconut water, Honey and Zobo

Physicochemical, sensory and microbiological quality of table wine produced from coconut, water, honey and zobo. Coconut water was collected and mixed with Zobo at a ratio of 5:1 and with honey also at 5:1 ratio. The various mixtures were fermented with wine yeast at room temperature (28±2 °C) for 7 days to produce table wine. There was no significant difference (P>0.05) in the fat, protein, ash and Carbohydrate content of all the wine samples, including control (commercial red and white table wines). Total Acid and alcohol content ranged from 0.576–0.921% and 5.87-11.50%, respectively. Sugar content ranging from 11.00-12.00%, however, difference in sugar content of all the wine samples were not statistically significant (P>0.05). The specific gravity of the coconut wines was significantly (P<0.05) higher than those of the control (commercial red and white wine). Total yeast count (TYC) on the fresh wine after 7 days’ fermentation period ranging from 7.66 Log10 CFU/ml to 8.91 Log10CFU/ml, with sample CWHN (coconut water and honey wine without yeast) given significantly (P<0.05) higher value of 8.91 Log10CFU/ml. Total bacteria count (TBC) on the aged wine (after 21 days of storage) ranged from 5.145 Log10CFU/ml to 6.230 Log10CFU/ml with sample CWH (coconut water and honey) wine given significantly higher value of 6.23 Log10CFU/ml. The taste of sample CWZ compared favourably with those of the commercial red and white wines. Sample CWZ (coconut/zobo wine) received equal overall acceptability with the commercial table wines.

DEVELOPING A TECHNOLOGY OF LOCAL WINES WITH THE ENHANCED AROMATIC PROFILE

Different methods of enhancing the aromatic profile of wines are researched throughout the world. One of them consists in adding unsaturated fatty acids to must as the yeast feeding. This work considers how the aromatic profile of dry white table wine made from the local grape variety Aromatny is influenced by the feeding that contains olive oil (a source of oleic acid) and the enzyme lipase and is added to must in combination with rehydrated active dry yeast Anchor Alchemy I (the species Saccharomyces cerevisiae). This method has been compared with the two other ones: with the classic method of obtaining dry white table wines by must fermentation (control) and with the sur lie method (when the dry white table wine material is aged on the lees for three months following the end of the must fermentation process). In the wines under study, 19 volatile compounds have been identified and quantified. These compounds, which are the most noticeable and active agents in aroma formation, include higher alcohols, organic acids, complex esters, aldehydes, terpene alcohols. The sample where the feeding was added is substantially higher in aroma-forming compounds than the other samples are. Also, this sample has the highest odour activity value (OAV). Sensory analysis of the wines considered has shown that the feeding containing olive oil and lipase has a positive effect on the aromatic profile of wine: in the aroma, there are distinct floral and fruity notes, more intense than those in the control sample an in the one obtained by ageing the wine material sur lie. This is possible due to a higher concentration of complex esters and a moderate content of higher alcohols. Adding the feeding results in no unpleasant tones in the wine’s odour, which are often caused by fatty acids, as their content is low. The advantages of the method suggested to enhance the aromatic profile of wines are its simple production technology and availability of the natural ingredients of the feeding. This research is supposed to help wine manufacturers satisfy consumers’ demand for local wines with their site-specific character, because one of the main motivations for tourists to visit the world’s wine-producing regions is an opportunity to taste unique wines with a pronounced and attractive floral-fruity aroma

COMPARATIVE ANALYSIS OF THE EFFECT OF WHITE AND RED TABLE WINES ON THE BRAIN OF WISTER RATS

The aim of this research was to investigate the possible effects of white and red table wine on the brain using Wister rats. Twenty-four (24) Wister rats weighing an average of 193g were purchased and identified at the zoological department of the University of Ibadan, Ibadan, Nigeria. The rats were randomly assigned to four groups of six rats each. Red wine (12% alcoholic content), white wine (12% alcoholic content), ethanol+H2O (12%) and distilled water (control), were administered orally and respectively for 10 days. Administration was done using syringe and tourniquets to each rat according to the kg body weight (10ml/kg body weight). The rats were later sacrificed and subjected to biochemical and brain homogenate analysis. The results show that the plasma and brain homogenate of rats administered White wines were significantly lower (p<0.05) than control for Total Cholesterol determination. Similarly, the plasma and brain homogenate of rats administered White wine were significantly lower (p<0.05) than control for Thiobarbituric Acid Reactive Substance (TBARS) determination. Meanwhile, other parameters like HDL-cholesterol, LDL-Cholesterol, Glutathione, Triglyceride, Total Protein, Uric acid and Creatinine were not significantly different from the control for plasma and homogenate analysis. In all, White wine was not found to express any trace of toxicity on the brain as opposed to Red wine. The study therefore shows that White wine are more healthy than red wines and as such when given an option between red and white, white wine should be preferred. Kukoyi, A. J. | Department of Biochemistry, Faculty of Pure and Applied Sciences, Federal University Wukari, P.M.B. 1020, Wukari, Taraba State, Nigeria

IMPROVEMENT OF THE BLENDING TECHNOLOGY OF MEDIUM DRY AND SEMI-SWEET WHITE TABLE WINES

The paper reviews the literature on the existing technologies of medium dry and semi-sweet table wines. The main problems of manufacturing this type of wines have been outlined, as well as how they are solved by domestic and foreign winemakers. The classical scheme of producing medium dry and semi-sweet wines allows retaining the aroma of a certain grape variety and obtaining quality wines, but it is not applied in Ukraine as it is technologically complicated and costly. The scheme that involves blending is far more economical, but does not allow retaining all the fine aromatic nuances of a variety. So, the article considers the ways of obtaining medium dry and semi-sweet wines using grape must that has been concentrated by freezing. It has been shown that this technology will allow retaining the valuable substances of the variety aroma and will be the basis for producing the highest-quality wines of this type. For the research, the following samples have been analysed: clarified must of the Rkatsiteli and Citronny Magaracha grape varieties, must concentrated by freezing, vacuum must, dry wine materials, and the medium dry white table wines made from them. In the musts and wines, the main physical and chemical characteristics have been studied (the mass concentrations of sugar, titrated acids, total and free sulphur dioxide), as well as some additional parameters (the pH, mass concentrations of phenolic substances, free and bound terpene alcohols, optical density with the wavelength 420 nm). The mass concentrations of volatile acids and the sensory characteristics of the wine materials and wines have been determined, too. The research has shown that in the medium dry wines obtained by cryotechnology, the concentrations of free terpene compounds increased from 1.01 mg/dm3 to 1.21 mg/dm3 in Rkatsiteli, and from 2.89 mg/dm3 to 3.24 mg/dm3 in Citronny Magaracha. The flavour and aroma improved substantially, too. So, the blending technology of producing medium dry and semi-sweet table wines using cryomust allows retaining, to the greatest possible degree, the bright and peculiar aroma of the grape variety, and obtaining the highest-quality wines of this type.

Controlled freeze-thawing test to determine the degree of deionization required for tartaric stabilization of wines by electrodialysis.

A controlled freeze-thawing test for wines is proposed to predict the deionization degree required for tartaric stabilization by electrodialysis. In this test, wine samples are frozen and then thawed in controlled conditions. The required deionization degree is estimated based on the difference of specific conductivity of the wines before and after the freeze-thawing cycle. The effect of freezing holding time and thawing time on the predicted deionization degree was investigated, using different types of red, rose and white table wines. For the recommended operating conditions, the freeze-thawing test gives reproducible results, which are between 5 and 9% higher than the corresponding values obtained by the mini-contact test at -4 °C during 4 h. The passive version of freeze-thawing test seems to be an expedite and reliable method that can yield in 24 h an estimate of the deionization degree of wines for tartaric stabilization by electrodialysis.

CREATION OF LOCAL WINES AS A METHOD OF FORMATION OF COMPETITIVE ADVANTAGES OF THE WINERY

The article proves the practicability of producing wine from local grapes for Ukrainian wineries. Thesubstantiation is based on the construction of five levels of goods and consumer values. The fifth level is awine that has a unique style: its character, temperament, expresses the peculiarities of the area where it isproduced. It has directed therapeutic properties due to the maximum content of nutrients from certain varieties of grapes and innovative technology. A business model of wine production in the chateau format hasbeen proposed. The mission, goals and strategies for such production have been developed. The mission isthe production of unique wines and the revival of winemaking traditions and wine consumption culture inUkraine. Target audience of consumers and competitive advantages have been determined. It is advisableto determine a competitive strategy for focusing on the manufacture of local wines. The marketing strategy ofgrowth has been proposed - the strategy of developing a new product. Namely - the organization of a fullproduction cycle for the manufacture of dry white table wines from the grapes of the new breeding generation by author's blend schemes. Market research has shown that production of local wines may become acompetitive advantage of Ukrainian winemakers for a rather long period of time. The competitive advantagesof "Chateau", which produce local wines, allow us to work effectively on the national and international markets.

Comparison of Rate-All-That-Apply and Descriptive Analysis for the Sensory Profiling of Wine

The aim of this work was to investigate how useful the Rate-All-That-Apply (RATA) method with naive consumers is to profile a wide range of wines and how the sensory profiles obtained compare with those of classic descriptive analysis (DA). For this purpose, we conducted two studies. Study 1 presents preliminary work comparing the discrimination ability of RATA, undertaken by 84 naive consumers, with a traditional DA with 11 trained panelists. The vocabulary lists remained the same across the two methods, and the assessment was based on a set of six red table wines (from six different varieties). Study 2 aimed to further elucidate the discrimination ability of RATA with 71 naive consumers compared with traditional DA. It expanded on Study 1 by increasing the number of samples assessed (12 white table wines from six varieties) and by varying the vocabulary between methods (RATA used a generic white wine attribute list and the DA used a panel-generated attribute list). In addition, similarity of sample configuration in the sensory space between RATA and DA was assessed by means of multiple factor analysis (MFA) and regression vector (RV) coefficients. The results of both studies revealed that RATA and DA are highly similar in sample discrimination ability (in terms of number of attributes significantly discriminating among samples). Furthermore, the MFA indicated high agreement in sample configuration between RATA and DA, reinforced by highly significant RV coefficients of 0.97 for Study 1 and 0.92 for Study 2. Overall, this observation supports a trend toward more consumer-centric approaches for sensory profiling and suggests that RATA could be a valid, accurate, and rapid addition to existing profiling methods used for wine.

ВЛИЯНИЕ ТЕМПЕРАТУРЫ НА ЭФФЕКТИВНОСТЬ ОБМЕННЫХ ПРОЦЕССОВ ПРИ БАТОНАЖЕ В ТЕХНОЛОГИИ ВИНОГРАДНЫХ СТОЛОВЫХ ВИН

The aim of the work was to study the influence of temperature on the efficiency of metabolic processes between the cell and wine material, in particular, on the changes in the concentrations of nitrogenous substances - amine nitrogen and amino acids, during the batonnage in the technology of white table wines. The object of the study was a white table wine material from the Sauvignon grape variety fermented with application of active dry yeast of Saccharomyces cerevisiae Killer (Bayanus) species of race IOC 18-2007 (France). At the end of fermentation the wine material was divided into four sample, stirred with yeast biomass and kept at different temperatures for 4 months: 1 - 4-6 °C; 2 - 10-12 °C; 3 - 16-18 °C (control); 4 - 22-25 °C. The obtained results showed that the activity of mass-exchange and oxidation processes increases with an increase in the temperature. Carrying out the batonnage is advisable at the temperature of 16-18 °C during 2-3 months with periodic stirring.

Optimization of the fermentation conditions of musts from Pedro Ximenez grapes grown in Southern Spain. Production of higher alcohols and esters

Musts from Vitis vinifera Pedro Ximenez grapes with sugar contents of 191, 241, 300 and 342 g/l were fermented at controlled temperatures of 15, 20, 25 and 30°C. The fraction of higher alcohols and esters was determined by GLC in a capillary column. By variance analysis significant differences (p~0,01) were obtained in the production of isoamyl alcohols and 2-phenylethanol at the different fermentation temperatures, while the hexanol-1 content was found to depend on the degree of ripeness of the grapes. Only the contents in 2-phenylethyl acetate and ethyl octanoate among the esters assayed were found to depend significantly on the fermentation temperature, and only that of hexyl acetate was found to depend on the degree of ripeness (p~0,01). Taking into account the production of ethanol, higher alcohols and esters, the best results were obtained at fermentation temperatures between 20° and 25°C, for both white table wines (12% v/v ethanol) and sherry type fine wines (15% v/v ethanol).

Classification of White Cultivar Wines by Origin using Volatile Aroma Components

Stepwise discriminant analysis was applied to gas chromatographic data of some volatile compounds obtmiieabjiTreonextracliOii"of dry white table wines. By means of this statistical method, successful classifications according to origin of Colombar wines from two regions, and Chenin blanc wines from three regions, were obtained. The components with the highest discriminatory value were i-amyl acetate, hexyl acetate and i-butanol, in the case of the Colombar wines and hexanol and 2-phenyl ethanol in the case of the Chenin blanc wines.

A flow-based platform for measuring the acidity parameters in wine

The present work describes a valuable tool for winemaking industry to measure the acidity parameters with rapid response, simple sample handling, with no or minimal pre-treatment. Thus, a sequential injection analysis (SIA) system with spectrophotometric detection was used as platform for the development of methodologies for the quantification of volatile and total acidity in wine samples. Both procedures make use of the same colour reagent, bromothymol blue (BTB) that changes its intrinsic colour in the presence of the acidity compounds. The volatile acidity value was attained with the separation of the volatile fraction of acids by means of a membrane separation technique, a gas-diffusion unit. For the total acidity value, the sample was merged with the colour reagent on the way towards detection. The fixed acidity is a result of the difference from the total and the volatile acidity.The presented tool displayed a low sample and reagent consumption, 346 and 102µL of sample and 37 and 32µg of BTB, for the volatile acidity (VA) and for the total acidity (TA), respectively. The observed limits of detection and quantification were 0.03 and 0.01gL−1 (VA) and 0.09 and 0.02gL−1 (TA) with high determination rates, 35 (VA) and 62 (TA) determinations per hour. The proposed system was successfully applied to the quantification of volatile, total and fixed acidity in white table wine samples. The obtained results were in good agreement with the ones obtained by the reference methods.

Shifts in climate suitability for wine production as a result of climate change in a temperate climate wine region of Romania

Climate change is causing important shifts in the suitability of regions for wine production. Fine scale mapping of these shifts helps us to understand the evolution of vineyard climates, and to find solutions through viticultural adaptation. The aim of this study is to identify and map the structural and spatial shifts that occurred in the climatic suitability for wine production of the Cotnari wine growing region (Romania) between 1961 and 2013. Discontinuities in trends of temperature were identified, and the averages and trends of 13 climatic parameters for the 1961 to 1980 and 1981 to 2013 time periods were analysed. Using the averages of these climatic parameters, climate suitability for wine production was calculated at a resolution of 30 m and mapped for each time period, and the changes analysed. The results indicate shifts in the area’s historic climatic profile, due to an increase of heliothermal resources and precipitation constancy. The area’s climate suitability for wine production was modified by the loss of climate suitability for white table wines, sparkling wines and wine for distillates; shifts in suitability to higher altitudes by about 67 m, and a 48.6% decrease in the area suitable for quality white wines; and the occurrence of suitable climates for red wines at lower altitudes. The study showed that climate suitability for wine production has a multi-level spatial structure, with classes requiring a cooler climate being located at a higher altitude than those requiring a warmer climate. Climate change has therefore resulted in the shift of climate suitability classes for wine production to higher altitudes.

Influence of bottle aging on the dynamics of quality indicators of wines of controlled names of origin

The method of bottle aging is used in the production of still and sparkling wines of high quality, pre-aged in barriques and without it in various wine regions of the world. The result of the study is investigation of bottle aging effect on the dynamics of quality indicators of white table wines of controlled names of origin produced in LLC «Industrial-trading company Shabo» (Odessa region, Ukraine). The object of the study were prototypes of white table wine-making materials produced from grape of Chardonnay, Riesling and Telti Kuruk varieties according to technological instructions developed by LLC «ITC Shabo».The main groups of aromatic components were defined, namely aliphatic aldehydes, dimethyl sulfides, acetaldehyde, aromatic aldehydes and aliphatic lactones, which were changed during the experiment. Prototypes of white table wines of controlled names of origin were prepared according to the technological instructions developed in the production of LLC «ITC Shabo» from Chardonnay, Riesling, Telti Kuruk varieties. Modes and bottle aging parameters for white table wine were developed: 6 months at a temperature of 12-15 oC.Analysis of the research results showed that the dominant flavor was furfural and 5-metilfurfurol that may be indicative of more than 6 months potential of these wines in the bottle.

A "Phenolic" Off-odour in White Table Wines: Causes and Methods to Diminish its Occurrence

The quality of some Kerner table wines often is rated inferior owing to the presence of an objectionable odour designated as medicinal, elastoplast (band-aid) or phenolic. Occasionally this odour is also encountered in wines from other cultivars such as Gewiirztraminer, Weisser Riesling, Muscat de Frontignan and Chenin blanc. The objectives of this study were to identify the compounds responsible for the off-odour and to establish possible relationships between their occurrence and vini-viticultural procedures. The component predominantly responsible for the medicinal odour was identified as p-vinyl guaiacol. This compound is known to be formed during alcoholic fermentation via decarboxylation of ferulic acid. Yeast strains, however, differed appreciably with respect to their ability to produce p-vinyl guaiacol. Most, if not all, of this component is apparently formed during alcoholic fermentation of grape juice. Only in one exceptional case was the presence of this odour detected in grapes from a crossing of Cruchen blanc x Servan blanc, which also contained relatively high levels of p-vinyl guaiacol. Wines made from grapes harvested at an advanced degree of maturity and in particular those exposed to sunlight, contained higher levels of p-vinyl guaiacol than did those from shaded grapes. Oxidation and subsequent treatment of grape juice with phenol-adsorbing fining agents such as activated charcoal, polyvinyl polypirrolidone, casein and gelatine (in combination with kieselsol and bentonite) led to decreases in the p-vinyl guaiacol levels and the concomitant medicinal odour intensity.