Standard Wine Research Articles

U.S. wine consumer preferences for bottle characteristics, back label extrinsic cues and wine composition

Purpose – The purpose of this paper is to examine what factors and assortment of factors on wine back labels, representative of those found in the US market, appealed to consumers. Moreover, what changes to wine bottle characteristics and standard wine composition appealed and could affect their purchasing decision. Design/methodology/approach – Data were collected through an online survey of 910 wine consumers who resided in Metropolitan Philadelphia and New York City. Findings – Based on conjoint analysis, averaged importance for food-wine-pairing information on wine bottle back labels was greater than both how to contact and connect with the winery and winery background information. Within the pairing information factor, description of food-wine-pairings and symbols of food-wine-pairings received positive utility values, indicating consumers preferred these options more than having no pairing information present. Consumers who purchased wine at least once a week were more positively impacted by the alternatives presented, with influence decreasing as purchasing frequency declined. Wine purchasing frequency is related to the number of wine drinkers living in a household and wine consumption within a household is most often a shared consumption activity. More females drink wine but the consumption frequency of males is higher. Practical implications – Producers considering changing either the wine composition or a bottle characteristic should note that, based on frequency of wine purchasing, changes that may invoke a positive response are: decreased calorie content, wine made from “sustainably farmed” or “naturally farmed” grapes, and producing USDA Certified Organic wine. Originality/value – This study is the first to investigate what changes to extrinsic cues in the form of wine bottle and back label characteristics and to the wine composition (taste) intrinsic cue appeal to consumers in the US market and might influence their purchase decisions.

Phenolic natural products of the wines obtained from three new Merlot clone candidates

This work aimed to evaluate the total contents of polyphenolics (the Ribereau-Gayon–Maurié procedure), anthocyanins (using pH differential method) and tannins (the Nègre procedure) as well as the content of phenolic acids (using UPLC/MS chromatography), respectively of the wines obtained from three new Merlot clone candidates in the perennial clonal selection. The aforementioned chemical parameters were determined in the samples covering the period 2009–2012. In comparison both with the standard Merlot wine (mother vine) and the wines obtained from other two clone candidates, the Merlot wine of the clone candidate No. 022 was found to have the highest total content of all three examined components 1.89 ± 0.05 g/L (polyphenolics), 185.59 ± 5.00 mg/L (anthocyanins) and 1.11 ± 0.03 g/L (tannins), as well as six phenolic acids including gallic acid (25.49 ± 0.27 mg/L). These findings are in good agreement with the observed trend for the viticultural parameters indicating the clone candidate No. 022 as more promising than mother.

Phenolic and Aroma Composition of White Wines Produced by Prolonged Maceration and Maturation in Wooden Barrels.

To investigate the phenolic and aroma composition of Malvazija istarska (Vitis vinifera L.) white wines produced by an unconventional technology comprising prolonged maceration followed by maturation in wooden barrels, representative samples were subjected to analysis by UV/Vis spectrometry, high-performance liquid chromatography, and gas chromatography-mass spectrometry. When compared to standard wines, the investigated samples contained higher levels of dry extract, volatile acidity, lactic acid, phenols, colour intensity, antioxidant activity, majority of monoterpenes, C13-norisoprenoids, methanol, higher alcohols, ethyl acetate, branched-chain esters and esters of hydroxy and dicarboxylic acids, ethylphenols, furans, and acetals, as well as lower levels of malic acid, β-damascenone, straight-chain fatty acids, ethyl and acetate esters. It was estimated that maceration had a stronger influence on phenols, and maturation on volatile aromas. Despite different vintages and technological details, the investigated wines showed a relative homogeneity in the composition, representing a clear and distinctive type.

Use of chemostat cultures mimicking different phases of wine fermentations as a tool for quantitative physiological analysis.

BackgroundSaccharomyces cerevisiae is the most relevant yeast species conducting the alcoholic fermentation that takes place during winemaking. Although the physiology of this model organism has been extensively studied, systematic quantitative physiology studies of this yeast under winemaking conditions are still scarce, thus limiting the understanding of fermentative metabolism of wine yeast strains and the systematic description, modelling and prediction of fermentation processes. In this study, we implemented and validated the use of chemostat cultures as a tool to simulate different stages of a standard wine fermentation, thereby allowing to implement metabolic flux analyses describing the sequence of metabolic states of S. cerevisae along the wine fermentation.ResultsChemostat cultures mimicking the different stages of standard wine fermentations of S. cerevisiae EC1118 were performed using a synthetic must and strict anaerobic conditions. The simulated stages corresponded to the onset of the exponential growth phase, late exponential growth phase and cells just entering stationary phase, at dilution rates of 0.27, 0.04, 0.007 h−1, respectively. Notably, measured substrate uptake and product formation rates at each steady state condition were generally within the range of corresponding conversion rates estimated during the different batch fermentation stages.Moreover, chemostat data were further used for metabolic flux analysis, where biomass composition data for each condition was considered in the stoichiometric model. Metabolic flux distributions were coherent with previous analyses based on batch cultivations data and the pseudo-steady state assumption.ConclusionsSteady state conditions obtained in chemostat cultures reflect the environmental conditions and physiological states of S. cerevisiae corresponding to the different growth stages of a typical batch wine fermentation, thereby showing the potential of this experimental approach to systematically study the effect of environmental relevant factors such as temperature, sugar concentration, C/N ratio or (micro) oxygenation on the fermentative metabolism of wine yeast strains.

Influence of different maceration time and temperatures on total phenols, colour and sensory properties of Cabernet Sauvignon wines

Maceration and fermentation time and temperatures are important factors affecting wine quality. In this study different maceration times (3 and 6 days) and temperatures (15 and 25 ) during production of red wine (Vitis vinifera L. Cabernet Sauvignon) were investigated. In all wines standard wine chemical parameters and some specific parameters as total phenols, tartaric esters, total flavonols and colour parameters (CD, CI, T, dA%, %Y, %R, %B, CIELAB values) were determined. Sensory evaluation was performed by descriptive sensory analysis. The results demonstrated not only the importance of skin contact time and temperature during maceration but also the effects of transition temperatures (different maceration and fermentation temperatures) on wine quality as a whole. The results of sensory descriptive analyses revealed that the temperature significantly affected the aroma and flavour attributes of wines. The highest scores for 'cassis', 'clove', 'fresh fruity' and 'rose' characters were obtained in wines produced at low temperature (15 ) of maceration (6 days) and fermentation.

Energy Drinks: What Teenagers (and Their Doctors) Should Know

1. Kwabena L. Blankson, MD* 2. Amy M. Thompson, DO† 3. Dale M. Ahrendt, MD‡ 4. Vijayalakshmy Patrick, MD§ 1. *Maj, US Air Force, Adolescent Medicine, Naval Medical Center, Portsmouth, VA. 2. †Maj, US Army, Adolescent Medicine Fellow, San Antonio Uniformed Services Health Education Consortium (SAUSHEC), San Antonio, TX. 3. ‡Lt Col, US Air Force, Program Director, Adolescent Medicine, Fellowship, SAUSHEC, San Antonio, TX. 4. §Psychiatrist, Brooke Army Medical Center Associate Professor, University of Texas Health Science Center, San Antonio, TX. Hundreds of different energy drinks are available and are marketed to adolescents, carrying the potential for substance abuse that involves caffeine and alcohol. Clinicians must be educated to deal with their patients’ use of these products. After reading this article, readers should be able to: 1. Understand the size and scope of the energy drink market and recognize common energy drink brands. 2. Know that adolescents are high consumers of energy drinks and use them as performance enhancers. 3. Know the contents of energy drinks and their adverse effects and safety concerns. 4. Know that energy drinks can be a cause of tachycardia, hypertension, obesity, and other medical problems in adolescents. 5. Know the dangers of mixing energy drinks with alcohol. 6. Understand the relationship between caffeine tolerance/dependence and alcohol tolerance/dependence. 7. Understand the importance of screening teenagers for energy drink use in the office setting and offering appropriate counseling. Energy drinks are caffeinated beverages advertised as boosting the immune system, enhancing performance, and creating a “buzz” or a “high.” Some of these drinks contain alcohol, and sometimes consumers mix them with alcoholic beverages. This article reviews current information about the content, benefits, and risks of the use of these energy drinks by adolescents. Adolescents are no strangers to energy drinks, and over the past 2 years, media reports have heightened the awareness of doctors, parents, and lawmakers. In 2010, nine university students in Washington State were hospitalized and one almost died; their illness was attributed to a fruit-flavored, caffeinated alcoholic drink. A month earlier, on a college campus in New Jersey, 23 students were hospitalized after becoming intoxicated, again reportedly after drinking the same …

Orthonasal aroma characteristics of Spanish red wines from different price categories and their relationship to expert quality judgements

Background and Aims: Research aimed to define the olfactory sensory spaces of Spanish red wines from different price segments and to determine relationships between sensory descriptors and quality as evaluated by experts. Methods and Results: A trained panel using a frequency of citation method assessed the orthonasal sensory characteristics of 96 Spanish wines belonging to three price segments (premium; high standard; low standard). Eleven robust sensory terms were built by combining similar terms using statistical criteria. A panel of experts consistently assessed quality. Negative aroma profiles, some of them very skewed, were identified in the different sets with ‘animal’, ‘undergrowth’, ‘vegetal’, ‘dried fruit’ or ‘evolved/oxidized’ notes. While skewed aroma profiles were not necessary for achieving low quality, the role of some terms was highly dependent on the category. ‘Dried fruit’ was positive in premium wines and negative in the other categories, in which its role was played by ‘berry’. The low standard wines had to be segmented into wooded and unwooded samples to find clear relationships with quality. Satisfactory models for quality could be built in all segments. Conclusions: Orthonasal aroma can explain wine quality. The sensory pair ‘woody/animal’ was confirmed as the most relevant and influential for wine quality. The role of the other terms depended on the category. Oxidation-related attributes are particularly detrimental to younger wines. Significance of the Study: The results provide a reliable and complete sensory database. They identified aroma profiles related to quality, provided an insight into the hierarchies of terms and provided information that will assist in the identification of the aroma chemicals potentially involved.

Partial Dealcoholization of Red Wines by Membrane Contactor Technique: Effect on Sensory Characteristics and Volatile Composition

Recently, the European Union regulation has fixed the maximum permitted dealcoholization level at 2 %; however in some cases, higher dealcoholization levels could be necessary. It is assumed that higher levels of dealcoholization could negatively affect the organoleptic quality of wine, but little data on this item is available. In the present study, two red wines (cv. Aglianico) with different initial alcohol contents (15.37 and 13.28 % v/v), were partially dealcoholized at three levels (−2, −3, −5 % v/v), by a polypropylene hollow fibre membrane contactor apparatus. In order to evaluate if dealcoholized wines differed from the untreated ones, triangle sensory tests were performed. Both −2 % wines were not perceived as different from the standard wines, while both −5 % wines were different. Sensory profiles and overall quality ranking were obtained by a selected and trained panel. Dealcoholization caused a modification of the sensory profiles, and the greatest differences were found after a dealcoholization of 5 % v/v. The most decreased olfactory notes were those of “Red fruits”, “Cherry” and “Spicy”, which is very important for the sensory quality of red wine. Concerning taste, both −5 % dealcoholized wines were more astringent than the correspondent untreated ones. Slighter differences were found for the other degrees of dealcoholization. The analysis of the volatile compounds, both free and glycoconjugated was performed by solid-phase extraction and gas chromatography mass spectrography analysis. While the composition of the glycoconjugated volatile fraction was almost not affected, many free compounds were decreased, most of all esters and alcohols, with an increasing amounts as the level of dealcoholization raised.

Acceptability of partially dealcoholized wines – Measuring the impact of sensory and information cues on overall liking in real-life settings

In this study, the effect of partial alcohol reduction in wine on consumer expectation and overall liking was investigated in real-life settings (by a Home-Use-Test). By varying the wine in the bottle and by manipulating the information on the label, it was possible to assess the relative impact of sensory properties and information cues on overall liking. Standard Chardonnay and Syrah wines were partially dealcoholized from about 13.5% to about 9.5%. After bottling, these dealcoholized wines were presented once with information about real alcohol content (9.5%) and once with false information about alcohol content (13.5%). A third bottle with standard wine inside was also presented with real information about alcohol content (13.5%). A group of 194 French wine consumers rated the three wines at home for liking before and after tasting on continuous hedonic scales. Another group of 90 French wine consumers evaluated the wines at the laboratory. The same order of preference was obtained in both laboratory and home conditions but wines generally attained significantly higher hedonic scores in Home-Use-Tests. A strong segmentation of consumers highlighted specific consumer behaviors regarding expectation and overall liking of wines. Results emphasized the importance of both sensory and information cues in the development of overall liking by consumers.

Preference and Acceptability of Partially Dealcoholized White and Red Wines by Consumers and Professionals

The influence of partial alcohol reduction in wine on consumer appreciation and acceptability was investigated. Two white wines (Chardonnay and Sauvignon blanc) and two red wines (Merlot and Syrah) were partially dealcoholized using reverse osmosis to span a range of three different alcohol contents (14% to 10%) by grape variety. A group of 79 French wine consumers comparatively rated their appreciation of these wines, first in blind tasting conditions and then with added information. A group of 35 French wine professionals also comparatively rated their appreciation of the same wines in blind conditions and described them by rating the intensity of 10 informal descriptors. Wine professionals did not like the sensory properties of reduced-alcohol wines, whereas consumer likings were less clear and masked a strong segmentation. Experienced wine consumers had similar ratings as the wine professionals and did not like reduced-alcohol wine, whereas less experienced consumers liked the sensory properties of reduced-alcohol wines. Reduced-alcohol wines were described by wine professionals as less hot, sweet, persistent, and balanced than standard wines. Once information about alcohol reduction was given, consumer likings changed and emphasized either the negative or positive effect of information, depending on the consumer. These findings highlight the importance of providing information on the sensory perception and liking of products.

Implementation of headspace solid-phase-microextraction–GC–MS/MS methodology for determination of 3-alkyl-2-methoxypyrazines in wine

A solid phase microextraction (HS-SPME)–GC–Tandem MS methodology was established for the analysis of 3-alkyl-2 methoxypyrazines in wine. Due to their low threshold value (2-methoxy-3-isobutylpyrazine, MIBP, 1 ng/l white wine, 10 ng/l red wine) these pyrazines contribute to the typical aroma especially of Sauvignon Blanc and Cabernet Sauvignon wines. The following fibers were tested, varying extraction time (30–80 min), extraction temperature (30–80 °C), ethanol concentration (1.25–6.25% vol) and ionic strength of salt added: carbowax/divinylbenzene (CW/DVB), polydimethylsiloxane/divinylbenzene (PDMS/DVB) and, divinylbenzene/carboxene/polydimethylsiloxane (DVB/CAR/PDMS) and carboxene/polydimethylsiloxane (CAR/PDMS). Best results were obtained with CAR/PDMS. 65 wines (41 Sauvignon Blanc, 24 Cabernet Sauvignon) of worldwide origin were analysed using the established method. The standard wine parameters (density, alcohol, total extract, pH, total acid, reducing sugar) were analysed according to FTIR method (WineScan Foss). MIBP was detectable in 14 Sauvignon Blanc wines, most of them from New Zealand (concentration 10–19 ng/l). In one manipulated Sauvignon Blanc wine from South Africa 173 ng/l MIBP was analysed, more than four to five fold the highest concentration ever found in wine. There is a correlation between the content of MIBP and the aroma profile analysis (descriptive analysis) with best results in a mediate concentration range up to 20 ng/l.

2004 The South African Wine Market

The wine industry's contribution to the country's gross domestic product is 16.3 billion rand. The total turnover of wine and alcoholic associated beverages amounted to 10.7 billion, of which R3.2 billion was exported. The industry provided direct employment for 257,000 people, and wine tourism for 59,000. There was a significant increase in local excise duty, and overall the standard wine prices increased noticeably during 2004.

Color variability for a wine sample poured into a standard glass wine sampler

AbstractSpectroradiometric color measurements were performed at 26 regularly spaced points of a standard wine sampler into which 100 cc of wine were poured. Our goal is to describe the color changes occurring in this system, but not to propose a new method for wine‐color measurement. Three samples of three different wines (red, rosé and white) were studied. From experimental measurements, lines of constant lightness (L), chroma (C,10) and hue‐angle (hab,10) were plotted for each wine poured into the wine sampler, as well as lines of constant CIELAB color differences (ΔE,10), with respect to a reference point placed at the axis of the wine sampler and at the zone with the greatest diameter. Considering different points of the wine sampler, the color attribute undergoing the greatest change was lightness (ΔL about 16.0, 15.0 and 11.0 for the red, rosé and white wines, respectively), followed by chroma (ΔC,10 about 2.8, 3.8 and 2.6 for the red, rosé and white wines, respectively) and hue(ΔH,10 lower than 1.0 for all the wines). Lightness variations were related mainly to the thickness differences between various zones of the wine sampler. Large color differences were found among the different points of the wine poured into the wine sampler (about 20.0, 21.0 and 14.0 CIELAB units, for the red, rosé and white wines, respectively). Panels should be aware of these large color variations when wine is visually assessed using standard wine samplers. It should be concluded that a single color specification for a wine poured into a wine sampler gives incomplete information, but hue, which is the main color attribute considered by observers, is nearly constant in the wine sampler. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 473–479, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10200

The Use of Candida pulcherrima in Combination with Saccharomyces cerevisiae for the Production of Chenin blanc Wine

Wine fermentations are conducted by naturally occurring or selected industrial wine yeast strains of Saccharomyces cerevisiae. However, non-Saccharomyces yeasts also occur naturally in fermenting grape musts, especially in the initial stages of the fermentation. It has been speculated that these yeasts can contribute to the overall characteristics of the wine. Generally, it is accepted that Kloeckera apiculata is the predominant non-Saccharomyces yeast species in grape must. However, it was shown previously that Candida pulcherrima was the predominant non-Saccharomyces yeast species in a grape must after sedimentation and prior to inoculation with commercial wine yeast. Subsequently, this yeast was investigated in laboratory and small-scale wine fermentations of Chenin blanc wine. As it could not ferment grape juice to dryness on its own, it was used in combination with a S. cerevisiae wine yeast strain. The effect of SO2, di-ammonium phosphate (DAP), pH and temperature on the growth of C. pulcherrima was also investigated. In combined fermentations, no change in overall fermentation rate or standard wine chemical analyses could be observed in comparison to a control S. cerevisiae fermentation. However, wine production in three consecutive years showed that the wine produced by the combined fermentation was of higher quality than that produced by the S. cerevisiae only.

Quality Changes on Storage of Caribbean Banana ( Musa acuminata ) Wines: Effects of Pectolase Concentration and Incubation Period

Fermentation studies investigated the effects of pectolase (P) percentages (0 ° , 0.15 ° , 0.5 ° , 1 ° ) at varying incubation periods (1 h, 4 h, 24 h) at 23 - 1 ° C on physicochemical, microbiological and sensory qualities of banana wines. Addition of enzyme had no effects ( p > 0.05) on percentage wine yield, degrees Brix, percentage alcohol, sulphur dioxide (SO 2 ), pH or titratable acidity except for ( p < 0.05) colour, volatile acidity and tannin content. Longer incubation period resulted in changes in all parameters ( p < 0.05) except degrees Brix, percentage alcohol and pH. Wines with 1% P (4 h) and 1% P (24 h) were judged as standard wines. Wine quality was stable for most parameters during storage at 22-25 ° C for 4 months with better clarity and lower SO 2 .

2000/2001 Survey of Winery Laboratory Proficiency

In 2000, the ASEV Technical Projects Committee's (TPC) Laboratory Proficiency Testing Guidance Committee established a continuous and frequent interlaboratory proficiency-testing scheme for the American wine industry. Results are reported for the first six rounds of the ASEV Laboratory Proficiency Testing Program for nine standard wine analyses performed in commercial winery laboratories. Proficiency was tested for analysis of ethanol, total and free sulfur dioxide, titratable acidity, volatile acidity, specific gravity, pH, residual sugar, and L-malic acid. The wineries were free to choose their methods of analysis, and the participants remained anonymous. Depending upon the assay, from 31 to 56 wineries participated, representing more than 90% of United States wine production capacity. The proficiency test showed satisfactory results in all rounds for the analysis of ethanol in wine with coefficients of variation among the wineries of 1.2 to 1.9%. The coefficients for titratable acidity (2.1 to 4.2%) and specific gravity (1.3 and 4.4% adjusted for table wine) were relatively low, but for the sulfite measurements, free (12 to 29%) and total (5.2 to 16%), they were considerably high. pH measurements on a logarithmic scale varied 5.7 to 9.1%. The combined relative errors for free SO2 and pH were between 19 and 39%, impacting the presence of sufficient amounts of molecular SO2 in the wines. Proficiency in the analysis of volatile acidity (6.7 to 25%) and malic acid (3.9 to 34%) was inadequate, as were the results for residual sugar (8 to 39%). The statistical results of the proficiency-testing program suggest a continuing need for improved laboratory quality-management systems. As a next step, wineries need to establish performance criteria for the different wine analyses that reflect the significance of their accuracy and precision for the quality and stability of wine. Acknowledgments: The ASEV TPC Laboratory Proficiency Testing Guidance Committee (Glenn Andrade, Gordon Burns, Christian Butzke, Janice Byington, George Peterson, Ray Walker) acknowledges the wineries who participated in the ASEV Laboratory Proficiency Testing Program, especially those who provided the commercial wines for the first six test rounds (E. & J. Gallo Winery, Trinchero Family Estates, The Wine Group, Ironstone Vineyards, Bronco Wine Company, Delicato Vineyards). Furthermore, the committee recognizes Terry Lee, E. & J. Gallo Winery, for chairing the original TPC subcommittee Analytical Quality and for his industry leadership and vision. We thank Patricia Howe, formerly of Ascent Laboratory, and Sue Weeks, Bibber International, for their valuable advice and participation in the ASEV TPC Winery Interlab Group meetings and the Preharvest Wine and Grape Quality Air and Road Show 2001. We are grateful to Christopher Czyryca, Collaborative Testing Services, for his management of the program and the preparation of the survey reports, a summary and analysis of which is presented here.

Note. Visual and Instrumental Color Evaluation in Red Wines

The color of 15 red wines from several wineries within the renowned wine-producing region Rioja (Northern Spain) was measured by spectrophotometric and spectroradiometric techniques and was visually assessed in a pair-comparison experiment by a panel of 10 experienced observers having normal color vision. Correlation between instrumental color measurements made by spectrophotometric and spectroradiometric techniques was very low, as expected from major differences in the experimental conditions employed (different illumination, path lengths and glass effects). Spectroradiometric measurements at the center of the wine sampler and at positions displaced 1 cm in the horizontal and vertical directions were quite different, mainly because of an increase of the lightness L*, the average color differences between them being high (3.5 and 2.6 CIELAB units, respectively). A 50% acceptance percentage resulted for a color difference of 2.8 CIELAB units, using a reference anchor-pair of wine samples with 4.0 CIELAB units. Thus, a value around 3.0 CIELAB units should be considered a preliminary estimate of the acceptable tolerance by the human eye for red wines poured in standard wine samplers.

A drink of water can improve or impair mental performance depending on small differences in thirst

Food and water are requirements for life, but eating and drinking have physiological costs as well as benefits. In the short-term a meal presents a challenge to bodily homeostasis and in response substantial physiological resources are deployed in digesting and absorbing the ingested materials and in utilising and storing the ensuing rush of nutrients into the blood (Woods, 1991). One consequence is a dip in mental (and physical) performance after eating; for example, the ` post-lunch dip'' (Craig, 1986; Smith et al., 1991). It is more surprising that the present study found that even the consumption of water can impair mental performance. In recent unpublished studies investigating thepsychostimulant properties of caffeine and caffeine-containing drinks we used plain tap water and no drink (` nothing'') as control treatments. In some studies these treatments had similar effects, but unexpectedly in others performance was found to be poorer after water than after nothing. The performance tasks were a demanding rapid visual information processing task (RVIP) as used here, and a simple reaction-time task.Wewere not able to find an explanation for these different results, although in the light of the present experiment it seems likely that differences in initial thirst were at least partly responsible (unfortunately, appropriate data on thirst were not collected). The observation that a drink of water can impair performance was confirmed and extended in the present experiment. Participants performed the RVIP task (Smit & Rogers, 2000) after consuming either nothing, or a small (120ml) or a moderate (330ml) volume of tap water, chilled in a refrigerator and served at 10 C. These volumes are equivalent to the amount of fluid contained in a standard wine glass and a standard soft-drink can, respectively. The 30 female and 30 male participants (mean SD ageˆ 26 7 years, and weightˆ 68 11 kg) were randomly assigned to one of these three treatments. They were instructed to follow their usual pattern of activity, eating and drinking (except alcohol was not permitted) up to the commencement of their 2-h test at either 11:00 a.m. or 3:00 p.m. The first 55min were occupied with an explanation of the study schedule, a familiarization session and pre-treatment measurement of RVIP performance, mood and thirst. Five min were allowed for drink consumption (participants assigned to the ` nothing'' condition sat quietly), following which the same measurements were repeated after two (mood and thirst only), 25 and 50min. Toilet breaks were permitted between measurement sessions. In the RVIP task, single digits (0±9) were presented in the centre of a computer screen at the rate of 100 per min (no inter-stimulus interval). Participants were instructed to press the spacebar on the computer keyboard as quickly as possible when they detected any unbroken sequence of three odd or three even digits. There were eight possible ` hits'' per min and the task lasted for 6min. Pre-treatment thirst, measured on a 9-point scale (` not at all'' to ` extremely'' thirsty) 2min before water consumption, was included as a between-subjects factor in the analysis of the results (median split of participants based on these pre-treatment thirst ratings). Thirst ratings for ` low'' and ` high'' thirst participants were (Mean and SD) 2.9 1.3 and 7.2 0.9, respectively, and time since last drink (measured to the time of the pre-treatment thirst rating) was 124 76 and 185 168 minutes, respectively. Consumption of water reduced thirst in low and high thirst participants in a dose-dependent fashion (main effect of treatment, p 0.2). The mood ratings revealed immediate, but not sustained, ` alerting'' and ` revitalising'' effects irrespective of the participants' initial (pre-treatment) level of thirst (Fig. 1a). For example, the main effect of treatment for alertness ratings was significant at 2min, F(2, 54)ˆ 3.82, pˆ 0.028, but not at 25 and 50min after consumption ( p> 0.3 for all main and interaction effects of thirst and treatment). In contrast, the effect of water on RVIP performance was very different between high and low thirst participants (Fig. 1b).When initial thirst was high, there was a dose-related improvement of performance, but when initial thirst was low there was a dose-related impairment of performance, thirst by treatment interaction F(2, 54)ˆ 7.59, pˆ 0.001. Pre-treatment performance (%hits) did not differ as a function of thirst or ` treatment'' and the thirst by treatment interaction was also non-significant ( p> 0.3). Post-treatment performance shown in Fig. 1b was analysed with pre-treatment E-mail of first-named author: peter.rogers@bristol.ac.uk

Spectrophotometric determination of copper after adsorption of its 1-phenyl-4,4,6-trimethyl(1H, 4H)-pyrimidine-2-thiol complex onto microcrystalline naphthalene

A selective Spectrophotometric method has been developed for the trace determination of copper after adsorption of its 1-phenyl-4,4,6-trimethyl(1H, 4H)-pyrimidine-2-thiol (PTPT) complex onto microcrystalline naphthalene. The complex is quantitatively adsorbed on naphthalene in the pH range 7.5–11.5, separated by filtration, dissolved in dimethylformamide (DMF) and determined spectrophotometrically at 400 nm. Beer's law is obeyed in the concentration range 2.5–37.5 μg of copper in 10 ml of DMF. The molar absorptivity and Sandell's sensitivity are 1.30 × 1041 · mol−1 · cm−1 and 0.0048βg cm−2, respectively. Ten replicate analyses of a solution containing 20.0 μg of copper gave a mean absorbance of 0.410 with a relative standard deviation of 0.91 %. The interferences of various ions have been studied and the method has been validated by the determination of copper in various standard reference materials, beers, wines, human hair, goat liver and environmental samples.

Spectrophotometric determination of iron after separation of its 9,10-phenanthrenequinone monoximate on microcrystalline naphthalene

A sensitive and selective spectrophotometric method has been developed for the determination of iron as Fe(II) or Fe(III) using 9,10-phenanthrenequinone monoxime (PQM) as the complexing agent. Fe(II) and Fe(III) react with PQM to form coloured water insoluble complexes which can be adsorbed on microcrystalline naphthalene in the pH ranges 3.7–6.2 and 2.0–8.4, respectively. The solid mass consisting of the metal complex and naphthalene is dissolved in DMF and the metal determined spectrophotometrically by measuring the absorbances Fe(II) at 745 nm and Fe(III) at 425 nm. Beer's law is obeyed over the concentration range 0.5–20.0 μg of iron(II) and 20–170.0 μg of Fe(III) in 10 ml of DMF solution. The molar absorptivities are 1.333 × 104 1 · mole−1 · cm−1 for Fe(II) and 2.428 × 1031· mole−1 · cm−1 for Fe(III). The precision of determination is better than 1%. The interference of various ions has been studied and the method has been employed for the determination of iron in various standard reference alloys, bears, wines, ferrous gluconate, human hair and environmental samples.