The importance of yeasts in determining the composition and quality of wines

From the wine makers' view point at present the advantages of the use of selected yeasts are the rapid and predictable onset of fermentation, its evenness and completion and the absence of undesirable aromas and flavours. However it is now apparent from our work that wine yeasts differ considerably in other characteristics which can also be of oenological importance. Compounds formed by yeasts which can directly affect the flavour of wines include hydrogen sulphide and mercaptans, iso-amyl alcohol, and ethyl and amyl acetate. Othex· aroma materials which are not reminiscent of pure compounds, but which affect wine quality, can also be produced. These may confer a quality improvement or, in the case of spoilage yeasts, a reduction in quality. Compounds which indirectly affect the quality of wines are those which bind sulphur dioxide and prevent it from carrying out its antioxidant and germicidal functions. The most important compounds in this connection in normal wines are acetaldehyde, pyruvic and a-ketoglutaric acid, and the amounts produced are influenced by the yeast strain.It is also possible to exercise control over reduction in acidity during the fermentation by controlling the amount of 1-malic acid metabolised by choice of a suitable yeast strain. Likewise some control is possible over the quantities of ethanol and higher alcohols produced and the prevention of off-flavours resulting from fermentation. One of the most important results of our work has been the prevention of hydrogen sulphide formation in wines. This formation is basically a microbiological reduction of elemental sulphur or sulphur-containing compounds during fermentation, and the control has been to carry out the fermentation with a yeast which is unable to produce hydrogen sulphide. Such yeasts exist naturally and may be selected on the basis of suitable laboratory tests. These yeasts need to have other desirable attributes such as high ethanol tolerance, the ability to carry out a regular and complete fermentation and to be able to grow fast enough to dominate the indigenous microflora.As a result of ·our investigations the use of selected yeasts has become widespread in Australian wine making, and the strain of yeast is now regarded as one of the controllable factors necessary to make wines of high and consistent quality

Diacetyl in Australian dry red wines and its significance in wine quality

The diacetyl content of 466 Australian dry red table wines ranged from less than 0.1 ppm to 7.5 ppm with a mean of 2.4 ppm. Malo-lactic fermentation had occurred in 71 per cent of the wines, which had a mean diacetyl level of 2.8 ppm. In wines which had not undergone malo-lactic fermentation the mean diacetyl level 1.3 ppm.Taste threshold tests showed that a difference of as little as 1 ppm could be detected in a light dry red wine containing 0.3 ppm diacetyl. In a full flavoured darker wine of higher quality containing 3 ppm the minimum detectable addition was 1.3 ppm.It is considered that diacetyl in amounts up to 2 to 4 ppm, depending on the wine, improved quality by adding complexity to the flavour. Above these levels the aroma of diacetyl became identifiable as such and resulted in a reduction in quality. The diacetyl content of a range of red table wines stored at 15° C showed a mean decrease of 19 per cent in diacetyl content in 4 months, 22 per cent in 8 months, 26 per cent in 12 months and 28 per c ent in 18 months

lnfluence of grape variety, climate and soil on grape composition and on the composition and quality of table wines

The influence of grape variety, soil type, climatic area and year of vintage on grape composition and wine quality was studied over a six-year period with three grape varieties in a eo-operative investigation. The wines were made under carefully controlled conditions to eliminate, as far as possible, any effect of winemaking technique. All viticultural and oenological treatments were replicated so that the data could be analysed statistically. When grapes from different viticultural areas were made into table wines, the quality of the wines was most closely related to grape variety, followed by climatic area and least of all by soil type.Reproducible differences in grape and wine composition were found for the grape varieties studied. For fhe same sugar content Riesling grapes and wine contained more acidity and a higher tartaric acid/malic acid ratio than Clare Riesling grapes and wine. They also contained less nitrogen, phosphorus and potassium. Shiraz grapes were relatively high in malic acid.The year of vintage strongly influenced the tartaric acid/malic acid ratio, particularly for Riesling and Clare Riesling, and also certain other constituents. Certain years could be designated as either high or low malic acid years for a particular grape variety.The soil type influenced the amounts of certain of the constituents of grapes and wine, but had no significant effects on the wine quality. Wines from the same varieties grown on two widely different soils in the same area could not be differentiated in replicated taste tests. The soil depth, drainage and waterholding capacity appeared to be more important than composition per se.Wines made from irrigated vineyards in the warm River Murray viticultural region, contained similar amounts of tartaric and malic acids, but were higher in pH, than wines made from the same grape varieties in the cooler non-irrigated Barossa Valley. Wines from irrigated grapes were generally of somewhat lower quality than those made from grapes of the same variety grown without irrigation in a cooler area. The time of harvesting irrigated grapes appeared to be critical to achieve the necessary balance between sugar, acid and flavour. Shiraz grapes grown under irrigation contained considerably less colour than grapes of the same variety grown without irrigation.Aroma was correlated with flavour in assessing wine quality, but numerical values ascribed to these parameters did not correlate generally with the wine constituents measured. A positive correlation existed between high tasting scores and high Ball/acid ratio

Control of framework interpenetration for in situ modified hydroxyl functionalised IRMOFs

Accepted for publication 31st August 2012By intimate control of reaction conditions, phase-pure crystalline porous metal-organic framework materials [Zn(4)O(L)(3)] with interpenetrated and non-interpenetrated structures can be synthesised. Under certain conditions, these reactions occur with concomitant deprotection of masked alcohols located on the organic links which yield accessible 'metal-binding' functional groups within the frameworks.Damien Rankine, Antonio Avellaneda, Matthew R. Hill, Christian J. Doonan, and Christopher J. Sumb

Prevention of conversion to abnormal tcd with hydroxyurea in sickle cell anemia: A phase III international randomized clinical trial

Children with sickle cell anemia (SCA) and conditional transcranial Doppler (TCD) ultrasound velocities (170-199 cm/sec) may develop stroke. However, with limited available clinical data, the current standard of care for conditional TCD velocities is observation. The efficacy of hydroxyurea in preventing conversion from conditional to abnormal TCD (\u3e/=200 cm/sec), which confers a higher stroke risk, has not been studied prospectively in a randomized trial. Sparing Conversion to Abnormal TCD Elevation (SCATE #NCT01531387) was an NHLBI-funded Phase III multicenter international clinical trial comparing alternative therapy (hydroxyurea) to standard care (observation) to prevent conversion from conditional to abnormal TCD velocity in children with SCA. SCATE enrolled 38 children from the United States, Jamaica, and Brazil [HbSS (36), HbSbeta0 -thalassemia (1), and HbSD (1), median age 5.4 years (range, 2.7-9.8)]. Due to slow patient accrual and administrative delays, SCATE was terminated early. In an intention-to-treat analysis, the cumulative incidence of abnormal conversion was 9% (95% CI 0 to 35%) in the hydroxyurea arm and 47% (95% CI 6 to 81%) in observation arm at 15 months (p=0.16). In post-hoc analysis according to treatment received, significantly fewer children on hydroxyurea converted to abnormal TCD velocities, compared to observation (0% versus 50%, p=0.02). After a mean of 10.1 months, a significant change in mean TCD velocity was observed with hydroxyurea treatment (-15.5 versus +10.2 cm/sec, p=0.02). No stroke events occurred in either arm. Hydroxyurea reduces TCD velocities in children with SCA and conditional velocities. This article is protected by copyright. All rights reserved

Oval Domes: History, Geometry and Mechanics

An oval dome may be defined as a dome whose plan or profile (or both) has an oval form. The word Aoval@ comes from the latin Aovum@, egg. Then, an oval dome has an egg-shaped geometry. The first buildings with oval plans were built without a predetermined form, just trying to close an space in the most economical form. Eventually, the geometry was defined by using arcs of circle with common tangents in the points of change of curvature. Later the oval acquired a more regular form with two axis of symmetry. Therefore, an “oval” may be defined as an egg-shaped form, doubly symmetric, constructed with arcs of circle; an oval needs a minimum of four centres, but it is possible also to build polycentric ovals. The above definition corresponds with the origin and the use of oval forms in building and may be applied without problem until, say, the XVIIIth century. Since then, the teaching of conics in the elementary courses of geometry made the cultivated people to define the oval as an approximation to the ellipse, an “imperfect ellipse”: an oval was, then, a curve formed with arcs of circles which tries to approximate to the ellipse of the same axes. As we shall see, the ellipse has very rarely been used in building. Finally, in modern geometrical textbooks an oval is defined as a smooth closed convex curve, a more general definition which embraces the two previous, but which is of no particular use in the study of the employment of oval forms in building. The present paper contains the following parts: 1) an outline the origin and application of the oval in historical architecture; 2) a discussion of the spatial geometry of oval domes, i. e., the different methods employed to trace them; 3) a brief exposition of the mechanics of oval arches and domes; and 4) a final discussion of the role of Geometry in oval arch and dome design

Red wine consumption increases antioxidant status and decreases oxidative stress in the circulation of both young and old humans

Background: Red wine contains a naturally rich source of antioxidants, which may protect the body from oxidative stress, a determinant of age-related disease. The current study set out to determine the in vivo effects of moderate red wine consumption on antioxidant status and oxidative stress in the circulation.Methods: 20 young (18&ndash;30 yrs) and 20 older (&ge; 50 yrs) volunteers were recruited. Each age group was randomly divided into treatment subjects who consumed 400 mL/day of red wine for two weeks, or control subjects who abstained from alcohol for two weeks, after which they crossed over into the other group. Blood samples were collected before and after red wine consumption and were used for analysis of whole blood glutathione (GSH), plasma malondialdehyde (MDA) and serum total antioxidant status.Results: Results from this study show consumption of red wine induced significant increases in plasma total antioxidant status (P &lt; 0.03), and significant decreases in plasma MDA (P &lt; 0.001) and GSH (P &lt; 0.004) in young and old subjects. The results show that the consumption of 400 mL/day of red wine for two weeks, significantly increases antioxidant status and decreases oxidative stress in the circulation.Conclusion: It may be implied from this data that red wine provides general oxidative protection and to lipid systems in circulation via the increase in antioxidant status.<br /