Dame-Jeanne The French word for a carboy. From this word has been derived the English word Demijohn. See Demijohn.

Damp Damp conditions are to be avoided in winemaking since any dampness within the winery will encourage the growth of moulds. Contrary to the belief of many people, a cellar ought not to be damp, but rather cool and dry, with maybe just a hint of moisture in the atmosphere.

Darkening due to Ascorbic Acid which is broken down to form brown colored compounds. It has been suggested that the use of ascorbic acid as an anti-oxidant should be avoided in wines made with ascorbic acid containing ingredients (citrus fruits, parsnip, potato, currants, raspberries and gooseberries). See Ascorbic Acid.

De-Amination Protein metabolism involves its breakdown to its constituent amino-acids. These in turn have the nitrogen containing group of atoms, or amine radicals, removed. This removal of nitrogen is called de-amination. In winemaking, the yeast requires protein building substances, and if these are not available here is a danger that the dead yeast cells will be broken down to provide some of the required nitrogen. This is a potentially dangerous situation, for, in the utilization of the dead yeast, amyl alcohol is produced; and this is poisonous. It is to prevent this synthesis that nutrients should always be used in all recipes.

Decanter Often of cut glass or crystal with silver mountings, they are as much table decorations as wine jugs.

Decanting Any wine with a sediment of crust in the bottle is best decanted before serving, both to increase its appeal and to prevent wastage due to stirring up the debris. To do this, the bottle is removed from the bin and, keeping it on its side, the cork is drawn. The wine is then slowly run into the decanter, looking through the wine at a light source, traditionally a candle. When the sediment reaches the neck, pouring is stopped. Wines which commonly require decanting are port and the red wines rich in tannin, such as Hermitage.

Decinormal A chemical term to describe the strength of solutions of acids or alkalis. A decinormal solution contains one-tenth of the molecular weight per liter. See Normal Solution.

Discoloring Any wine which is too dark in color may be reduced in intensity by the use of discoloring agents such as charcoal or eggshell.

Demerara An unrefined cane sugar, brown in color. It is of use in dessert wines where a golden color is often required.

Denaturing The structure of protein alters when acted on by heat or alcohol. The breakfast egg is a good example of denatured protein; when cooked it changes from runny and translucent to white and opaque. This phenomenon may occur when fortifying a wine which has apparently insufficient protein to cause a haze. After a few days, the fortified wine will show a haze which is positive to tests for protein. This is due to denaturing by the added alcohol. Cure is by normal methods of protein removal. See Iso-Electric Point.

Density The density of a substance is its weight per unit volume; thus a heavy substance has a high density, and vice versa. Although a pound of feathers weighs the same as a pound of lead, the latter has a smaller volume and hence a higher density. Upon this principle is based the hydrometer, which works on the fact that a dense liquid can support more than a light liquid. (The common example given is that it is easier to float on the sea than in the bath.)

DEPC  See Cellulose.

Depectinising Enzymes See Protein entries ; See Enzyme.

Designing Recipes rests on the ability to emulate the desired qualities of a wine. From a resting brief of the planned character, the recipe can be roughly drawn up and, after analysis of the ingredients, the final touches, such as acidity, gravity and required additives can be estimated and adjusted as necessary.

Dessert Fruits tend to be more fragrant, higher in sugar and lower in acid than their cooking counterparts and, when making wines from such ingredients, these points must be remembered and due allowance made

Dessert Wine is intended for drinking at the end of a meal, often accompanying fruit. Accordingly, they tend to be higher in alcohol content, sweeter and with a fully body than table wines. The color is not important, except that it should be deep; and may be golden or brown, or one of the normal shades. The bouquet must be pronounced, lest the dessert overpower the wine. Similarly, the flavor must be stronger than table wines

Detergents Chemicals used for washing winemaking equipment. While they are invaluable for this, they can ruin a sparkling wine. This is because the way in which they remove dirt is by lowering the surface tension, thus making it more soluble. Due to this lowering of the surface tension the gas in a sparkling wine will escape rapidly. The solution is to ensure thorough rinsing after their use. The same is therefore best done despite claims to the contrary with detergents designed for the wine trade. At the same time this rinsing will prevent any taint that might arise due to their use, although they are claimed not to do so.

Determination of Constituents of Wine See Test Entries.

Dextrans are chains of sugars, shorter than starch chains. They are formed by the action of spoilage bacteria such as Leuonostoc. Prevention of this disorder, which may be recognized by a slimy deposit, is by sulphiting before fermentation. To cure the trouble, the wine is stirred and after sulphiting and settling the wine it can be racked and restarted.

Dextrins are composed of medium-length chains of glucose and are usually present as the result of starch breakdown or partial destruction of pectins. If present, there will be a haze which may be difficult to clear. To determine the cause and, therefore, the partial cure See Diagnosis of Faults, Appendix XI.

Dextrocheck A test reagent in tablet form which measures the concentration of glucose in the wine. It is essential in the making of sparkling wines to know the residual sugar before dosage. The method of use is described under Sugar Estimation in Wine. (Common trade name is Clinitest.)

Dextrose The old name for glucose, given because of its property of rotating polarized light to the right.

Dextrose Monohydrate A form of sugar, akin to invert sugar. Its use is not necessary since it is doubtful if its use confers any benefit on the wine. All that it will do is to remove one of the chemical steps in alcohol production (the hydrolysis of sucrose to its component sugars, glucose and fructose), which the yeast is quite capable of performing itself. Used mostly in brewing beer, it is 100% fermentable, creating a very dry end product. Also known as brewing sugar or corn sugar.

Diabetes A disorder of sugar metabolism, common in man. A sufferer from this is always advised not to drink alcohol, but the occasional glass of dry wine is not unduly harmful. Allow for the calorific value in the daily diet about 80 calories per 100 ml, and the carbohydrate content of 6 grams percent.

Diabetic Wine While there is no such thing as a diabetic wine, a completely dry wine may be considered safe. If required it may be sweetened with a non-fermentable substance such as sorbitol which is not metabolized in the human body.

Diacetyl A bitter-tasting substance produced by some of the lactobacilli, possibly by breakdown of some of the tannins. Prevention is by sulphiting the must prior to fermentation. Cure is sometimes possible by sweetening. Usually, however, the taste is not maskable and the wine should be discarded.

See Diagnosis of Faults See Appendix XI.

Diethyl Pyrocarbonate A compound which has a stabilizing effect on wine by killing bacteria or yeasts present. In theory it should be the ideal stabilizing agent because, like ethyl pyrocarbonate it is broken down to alcohol.

Diffusion All physical substances tend to pass from an area of high concentration to one of low concentration by diffusion. Yeast cells do not possess the ability to take in substances by chemical reactions, but can only do so if a substance is in solution and its molecular size is small enough to pass through the pores in the cell surface.

Dihydro-Acetate A hydrogen acceptor present at the beginning of fermentation before acetaldehyde is formed to take over this role. The acceptance of hydrogen ions by di-hydroxy acetone results in its reproduction to glycerin.

Dilution A necessary step in the production of wines from most amateur ingredients to lessen factors such as over-acidity, overpowering flavor or bouquet. The amount of dilution depends on the initial assay of the juice extracted from the ingredients. Any dilution will in most cases lead to a low level of additives and ingredients, and this must be allowed for in calculations. Most commonly, this decrease is in the sugar and acidity levels, which must be corrected. All kit wines require dilution of the concentrate in accordance with the instructions, but the levels of all ingredients have been adjusted to be correct in the final volume.

Dilution and Acidity If the volume of a fruit juice is doubled by adding water, it is obvious that the concentration of its constituents will be halved. Dilution of fruit juices is most often undertaken to lower an over-high acidity. If, after initial assay, the acidity of the juice is too high for the intended wine style, it is easy to work out by how much the juice needs to be diluted to bring it down to an acceptable level. The converse may be true; dilution may cause to low an acidity, in which case acid needs to be added.

Dilution and Alcohol When making a wine, there is always a loss of volume at racking time. To make this up entails adding either water with its consequential dilution of the alcohol, or, to prevent this, by using a topping-up wine. Another possibility is to make the wine stronger than its required strength. Dilutions after racking with water will then bring the level down to the planned strength. See Water.

Dilution and Color White wines have no problems here, but if a deep red wine is wanted it is not a good idea to top up with water after racking, since it will dilute the color. To avoid this, red wines should be made to a greater volume than the final carboy, so that at each racking there will be either smaller or fewer carboys.

Dilution and Flavor Dilution will result in less flavor. This can be useful in correcting an over-flavored wine such as elderflower. Care must be taken with the diluent, but blending with a bland wine or a neutral topping-up wine will give a better result.

Dilution and Nutrients When starting a fermentation, it is nearly always of a smaller volume that the finished wine and it is necessary to allow for this when adding nutrients. Thus, add the recommended quantity per final gallon and not per initial gallon.

Dilution and Specific Gravity The effect of diluting any liquid is to lower its specific gravity. If one gallon of fluid with a specific gravity of 1200 is diluted to 2 gallons, the specific gravity will fall to 1100. Alternatively pressed, the gravity will be halved from 200 to 100. Allow for diluting to the final volume when adjusting the S.G. of the must.

Dinner Wines Usually with an alcohol content of 10 or 12 percent, they should be chosen with the object of complementing the food. The snobbery of drinking wine x with menu y is now generally out-of-favor and choice is often based on personal preference alone. Table wines usually have medium body and are dry or medium. The flavor must not be so overpowering as to mask the taste of the food. 

Disaccharides These are sugars composed of two monosaccharides joined together. Sucrose (cane sugar) is made up of one molecule of glucose and one of fructose, and is the most important disaccharide in winemaking. See Sugars (Disaccharides)

Discoloration See Color of Wine ; See Dried Blood ; See Diagnosis of Faults, See Appendix XI.

See Diagnosis of Faults, Appendix XI.

Dissociation The characteristics of an acid in solution, when it splits into its constituent parts which, by definition, must include hydrogen ions.

Distillation of Spirits is usually illegal without a license from appropriate government authorities. It involves heating a liquor to such a temperature that water and certain of the substances which are toxic in any appreciable concentration (such as fusel oils) are separated from the alcohol and bouquet-conferring esters, known as congenerics. If distillation is attempted without proper equipment there is a real danger that the poisonous substances present will be concentrated by the process and not driven off.

Dom Perignon A monk of the Benedictine order in the 17th century credited for first using cork to seal wine bottles and thereby showing the way tot he production of vintage wines, for, without a sure method of protection, the wine will become infected. His memory has hallowed in the Champagne which bears his name.

Dosage The French term used by champagne producers to describe the technique of adding the mixture of cane sugar, wine and spirit to Champagne after Disgorgement.

Doubling up The technique used to restart a stuck ferment. A fresh yeast started is prepared and once active is added to about an equal volume of stuck wine (after racking). When this is fermenting, the volume of wine in the fermentation carboy is doubled. Each time the ferment is active the volume is increased until all the wine is restarted.

Doux The French word meaning sweet, which is often used on the label to describe such a wine.

Dried Flowers are a convenient way of using flowers all the year round. They do not produce quite the same bouquet as their fresh counterparts. Broadly speaking, 1 oz of dried flowers is approximately equal to + gallon of fresh flowers, with the exception of elderflowers, where 1 oz equals 1 gallon of the fresh flowers.

Dried Fruit cannot be processed by pulping or pressing techniques such as are used for the majority of fruits. They have to be rehydrated so that sugars and flavorings can be leached out. Sterilization is essential since they tend to have a high micro-organism population. The possible methods of extraction are either to boil the dried fruit for about + hour, or to pour boiling water over the fruit and press. When the temperature has dropped below 85¦F, sulphite is added to sterilize the must. Pulp fermentation is valuable with dried fruit since it allows a longer time to extract as much flavor and color as is required by the action of alcohol as it is formed.

Dried Malt The main use of dried malt to the winemaker is in the preparation of starter mixtures. There are specialized recipes which include this ingredient.

Dried Yeast One of the basic forms in which yeast can be purchased. To make a starter, simply add the recommended amount to the starter solution

Dryness is detected by the lack of sugar on tasting a wine. This should not be confused with astringency, detected by a dryness in the mouth, due to tannin.

Disgorgement See Disgorging.