Winemaking

The addition of a substance (additive) to wine or beer must follow three simple rules  

In winemaking, the quality of the harvested fruit influences the quality of the resultant wine via the chemical composition of the fruit, particularly the parameters, fermentable sugar, acidity and pH, phenolic and flavour components, and protein. Grapes of good quality are a fundamental prerequisite if the winemaker is to produce good wine, to the extent that premium quality wine can only be made from high quality fruit. The 

---

In enzymes, this folding process is crucial to their activity as catalysts, with part of the structure as the center of reactivity. Heating enzymes (or other treatments) destroys their three-dimensional structure so stops further action. For example, in winemaking, the rising alcohol content eventually denatures the enzymes responsible for turning sugar into alcohol, and fermentation stops. 

During the Middle (Dark) Ages, wine and winemaking along with other sacraments and knowledge were husbanded in cloisters and enclaves which maintained the pockets of sophistication that enabled the later flowering of the Renaissance (9,10). Wine became further associated with art, letters, religion, and culture, and it remains so. 

Port-type ted dessert wines require skin contact time to extract the anthocyanins, but the fermentation must be short to retain the sugar level neat the 6—10% level desired. The winemaker cannot always achieve desired composition in individual lots. In order to teach the desired standard, it is necessary to make new lots to enable blending to that standard. The right volume of a tedder, less sweet wine will need to be made to bring to standard a lot with low color and mote sugar, for example, while keeping the alcohol also within the desired limits. 

C. S. Ough, Winemaking Basics, Haworth Press, Binghampton, N.Y., 1992. 

The dry yeasts have excellent storage stabiUty, up to a year or more if packaged under an inert atmosphere (N2, CO2, or vacuum). First introduced into the United States and then AustraUa, they are now being introduced into European winemaking as well. A number of strains of S. cerevisiae S. bayanus and S. fermentati are available. 

The sugars in fruits such as grapes are feimented by yeasts to produce wines. In winemaking, lactic acid bacteria convert malic acid into lactic acid in malolactic fermentation in fruits with high acidity. Acetobacter and Gluconobacter oxidise ethanol in wine to acetic acid (vinegar). 

Sodium bisulfite is often combined with an acid such as citric acid to make it produce gas faster. It is also used to sterilize winemaking... 

The winemaker is always facing problems due to the weakness of grapes which composition is variable and different for each vintage. He tries to prevent oxidation and to work with soft conditions to preserve grapes components important for the wine s equilibrium. The sanitary state of the harvest is of first importance Grapes composition depends on the variety, terroir, viticulture and climatic conditions. The main objective for the winemaker is to keep and valorize grape components like aromas which will determine the quality of the wine... 

The future will be to manage the extraction of precusors of aromas from the grape during the skin contact steps of white and red winemakings... 

To prevent the formation of wine crystals during the bottling process, winemakers use a method known as cold stabilization. By lowering the temperature of the wine to 19-23°F for several days or weeks, the solubility of tartrate crystals is lowered, forcing the crystals to sediment. The resulting wine is then filtered off the tartrate deposit. The temperature dependence of the solubility of potassium bitartrate is readily apparent in the following comparison while 162 ml of water at room temperature dissolves 1 g of the salt, only 16 ml of water at 100°C are needed to solubilize the same amount of saltJ l Recent developments employ a technique known as electrodialysis to remove tartrate, bitartrate, and potassium ions from newly fermented wine at the winery before potassium bitartrate crystals form. 

METEX [Metal extraction] A process for extracting heavy metals from industrial waste waters by adsorption on activated sludge under anaerobic conditions. It is operated in an up-flow, cylindrical reactor with a conical separation zone at the top. Developed by Linde, originally for removing dissolved copper from winemaking wastes. First commercialized in 1987. 

If winemakers corked their bottles like some people cork their flasks, there d be few oneophiles and we d probably judge good years for salad dressings rather than wines. You don t just take a new cork and stick it down into the neck of the flask, vial, or what have you. You must press the cork first. Then as it expands, it makes a very good seal and doesn t pop off. 

M. Swanepoel and K.H. Esbensen, Representative sampling at the grape intake a critical issue - ofteu forgotten, Australian and New Zealand Grapeowner and Winemaker, 521, 32-37 (2007). 

Baldwin, G. (1992). Filterability can be improved by fining. Aust. Gmpegrower Winemaker 344, 21-22. 

Sitters, J. H. and Rankine, B. C. (1980). Identification of hazes and deposits in wine. Aust. Grapegrower Winemaker 17. 

Dugelay, I. et al.. Role of cinnamoyl esterase activities from enzyme preparations on the formation of volatile phenols during winemaking. J. Agric. Food Chem. 41, 2092, 1993. 

A similar study by Verrelli and coworkers, based on PCA of potentio-metric data, allowed the differentiation of Verdicchio wines according to the winemaker and the vintage. Furthermore, MLR and PLS models, validated by means of cross-validation, permitted the quantification of a number of oenological parameters, such as SO2, L-malic acid, and the total phenols content (Paolesse et al., 2008 Verrelli et ah, 2007). 

---