Metabisulfite The complex organs which combine together to analyze taste are the palate, nose, mouth and brain. The nose tastes the volatile elements of the flavor, while the mouth and palate analyze the liquid part. It is interesting to note that with the nose occluded (as with a cold), taste is an almost useless function

Parts per Thousand Acid analysis of a wine is expressed as parts per thousand of sulfuric acid. This is simply the grams of acid present in one liter of the wine.

Pasteur The French scientist who proved the need for oxygen in the aging of wines. He also proved existence of acetobacteria by showing that a wine kept sealed or which only received filtered air did not become infected, while a wine left open rapidly became infected. From this he disproved the theory of spontaneous generation of life.

Pasteurization The heating of liquids to a temperature of 140¦F for 3-4 minutes. This has the effect of killing nearly all bacteria and coagulating proteins. If this is practiced with wines it has the effect of stopping maturation as the enzymes involved are all denatured (or destroyed).

Pearson Square The equation for working out spirit additions for fortification. See Fortification; Appendix XVI.

Pectic Enzymes and Tannin A red wine with a pectin haze will tend to clear better than a white wine, because the latter has almost no tannin. This group of acids being oppositely charged to many of the colloidal hazes will help to clear a wine so afflicted by neutralizing the charge on the haze-causing pectin. See Additives

Pectin and Boiling Pectin is more soluble at higher temperatures, which is one of the main reasons for trying to avoid heating ingredients when preparing a must. Also, in heating or boiling a pectin-containing fruit, the natural pectin destroying enzymes are denatured, making the use of pectic enzyme even more imperative.

Pectin Enzymes and Extraction By breaking down the pectin in the fruit cell wall greater yields of juice can be obtained. If heating techniques have been used allow the juice to cool before adding the enzymes, to avoid denaturing

Pectin Glycoside The active enzyme in Rohament P which breaks down cellulose connective tissue in fruits to increase juice yield. Pectinase must be used with this enzyme to prevent pectin hazes.

Pectin Haze As molecules of pectin have electrical charges, they are one of the causes of colloidal hazes in wines. By adding pectic enzymes, the haze will not necessarily clear, since the electrical charge can be transferred to other particles. If the use of Pectinase is not practiced prior to, then it must be used after fermentation, and a period allowed for natural clearing followed by fining.

Pectin Occurrence Pectin is present in all fruit to some extent. The riper the fruit, the greater the amount. Fruit that are especially high in pectin are apricots, citrus, peaches and plums. The North American cherry has a low content.

Pectin Removal is best done immediately after any extraction method during must preparation. DO NOT ADD ENZYMES TO A HOT SOLUTION. It is a good idea to use pectic enzymes routinely when preparing the must rather than trying to clear a pectin haze in a finished wine.

Pectin, Action of In nature pectin is one of the main structural components of plant cell walls. If extracted into solution, it will tend to gel (which is hoped for in the making of jams). When present in a wine, it is not (or should not be), in such a concentration as to produce a jelly. It will, however, cause a haze if not broken down during fermentation.

Pectin, Test for 15 ml of methylated spirit added to 5 ml of wine will cause gelling of pectin if present. This is usually visible as small clots forming in the test solution. These may take up to two hours to appear.

Pectinase The naturally-occurring enzymes which can break down some of the pectin extracted from fruit during must preparation. If heat is used for this, the enzyme will be denatured. The commercial preparations of pectin-destroying powders or solutions contain the same enzyme.

Pellicle The skin which forms on the surface of a wine infected by certain of the spoilage bacteria. A sherry flor is the one example of a pellicle which is beneficial to wine.

Penicillium Species of mould best known as antibiotics which may grow on a wine not kept under anaerobic conditions. They can be recognized by the blue-green or white color in a hairy growth. Prevention is by hygiene. Cure is possible by removal of the mould, sulphiting and racking, followed by restarting. If the wine is tainted, it should be discarded.

Pentose One of the main groups of monosaccharides. They are characterized by five carbon atoms in their structure. An example is arabinose. Pentoses are not fermented by wine yeasts.

Peptide Link The special chemical bond between amino acids, whereby they join together to form proteins. The bond is between the amine radical of one acid and the carboxyl radical of the next.

Perry An alcoholic drink made from pears; similar to cider.

pH and Acidity A wine is a buffer solution. If acid is added, although the acidity will rise, the pH may not alter due to this buffering effect.

pH and Spoilage One of the main applications of pH to winemaking is in the prevention of infection. It is will known that most bacteria cannot reproduce if the pH is below 3.5. At this point yeasts are not inhibited. Thus it is always worth checking that he pH is about 3.5 before pitching the yeasts. A well prepared must usually has a pH of about this value.

pH Measurement The simplest and cheapest method is to use narrow range pH papers. One drop of wine is placed on a strip of paper and after the color has developed it is compared with the result chart. For winemaking, the paper with a range from 1 to 4 is adequate. For the rich, the pH meter measures the pH by the conductivity of the solution. See Indicator Paper

Phenol The six carbon ring structured compound which forms the basic structure for the tannins.

Phenolphthalein A weak acid which changes color from colorless to red at about the neutral point (pH 7). It is widely used for titrating weak acids with strong alkalis, such as is performed in winemaking. See Acidity, Measurement of.

Phylloxera The aphid which almost destroyed the whole of the European vineyards in the 1870s. The vines now used are American hybrids which are resistant to this disease.

Pichia A genus of yeast present in the sherry flor. It is a spoilage organism to a table wine, but it is essential for flavor development in sherries. It does not metabolize sugar to alcohol, but instead to aldehydes.

Pip The seed of fruit. In tannin-containing fruit and berries, the pips have a higher tannin content that the rest of the fruit. In red grapes, the pips may contain up to 50 percent of the total tannin. If a low tannin wine is wanted, do not press the pips, and if possible exclude them from pulp fermentation.

Pipe The special name given to barrels used for Port.

Pipette An accurately calibrated tube which, when filled to the mark etched upon it, contains a precise volume of solution. For winemaking, a 5 to 10 ml pipette is needed for acidity measurement.

Plastering The technique of adding gypsum to a sherry must.

Plastic Barrels Provided of a food grade and not tainted by previous contents, such a container is of value for short term storage. Their long term usage is not recommended. Plastics do not admit air in the same way as wooden barrels, so it is unlikely that they are satisfactory for aging.

Poisonous Plants Any plant known to produce edible fruit will produce some kind of wine. Poisonous fruit = poisonous wines. If in doubt, do not experiment. It is beyond the scope of this book to give a detailed list of dangerous plants.

Polarization A phenomenon demonstrated by the sugars. Light is made up of light waves which travel in all planes around a point. If a light is shone through a sugar solution, the light does not pass through the solution in some of the planes; i.e., it is polarized.

Polysaccharide Sugars made up of many sugar molecules. See Dextrin ; See Pectin ; See Starch.  

Polythene One of the better plastics to use for winemaking. It is a high density material which does not strain easily, nor does it pick up off flavors.

Pome Fruits A type of fruit in which the edible flesh surrounds a core containing seeds. They include apples and melons.

Port A fortified wine made in Portugal from the region around Oporto. Before fermentation is completed, the yeast is inhibited by the addition of brandy so that is remains a sweet wine. It requires long maturing and careful handling due to the crust which forms in the bottle. It is usually a blended wine, unless the quality warrants a vintage being declared.

Positioning Bottles Table wines and port should be stored, (or laid down), on their sides so that the wine keeps the cork moist and swollen to prevent shrinkage and possible infection. Fortified wines are usually stored upright to avoid dissolution of the cork by the high alcohol content.

Potassium Bitartrate See Argol ; See Bitartrate ; See Cream of Tartar.

Potassium Hydrogen Tartrate The intermediate compound between the soluble tartaric acid and the insoluble potassium bitartrate.

Potassium Metabisulphite One of the available forms of Metabisulphite

Pourriture Noble See Botrytis.

ppm The abbreviation for parts per million. It is usually used for sulphite dosage.

ppt The abbreviation for "parts per thousand" which is used as the unit of acid measurement.

Precipitate An insoluble compound formed by chemical reaction between two compounds in solution; i.e., Potassium phosphate and tartaric acid combine to form potassium bitartrate.

Precipitated Chalk See Calcium Carbonate

Preparation of Bananas Peel and slice the fruit. Boil for + hour (with or without the skins, depending on the recipe). Then strain and press lightly. If pulp fermentation were to be used, the fruit would break up into an easily disturbed sediment. As it is, even with this method of preparation, banana containing wines tend to have a large sediment.

Preparation of Flowers, Fruit, Red Fruit, Rhubarb, Vegetables See respective entries.

Press Although not an essential piece of equipment for the small producer, it is useful to have one when large quantities of fruit have to be processed. Always wrap fruit, after crushing or pulping, in cloth. This will prevent the holes in the press becoming clogged by particles of pulp. Do not apply maximum pressure immediately but, after each run of juice, increase the pressure. This will increase the yield and also not put too great a strain on the press.

Pressure Cooker A sealed pan in which it is possible to build up a considerable pressure, thereby reducing the cooking time.

Pressure in Sparkling Wines See Champagne Bottles, Pressure in.

Primary Fermentation See Fermentation, Primary.

Proof The alcohol measuring scale. In the UK, 100% proof equals 57.1% alcohol, while in the U. and Canada, 100% proof equals 50% alcohol. In Europe the Gay Lussac scale is used instead, wherein the percentage alcohol equals the degrees Gay Lussac. See Appendix V.

Propionic Acid is formed by the breakdown of tartaric acid as a result of an infection known as Tourne. The bitterness in a wine so affected is due to the acid produced. Should this infection occur, the wine must be discarded and the winery thoroughly cleaned. Prevention is by attention to hygiene.

Protective Colloid If a wine contains electrically charged particles, they may give their charge to neutral particles in the wine. These newly charged particles often form a haze which proves difficult to clear. The common example of such a haze is one due to pectin.

Protein Haze A wine low in tannin (usually white) may have a slight haze due to protein. Bentonite fining is the usual method of treatment.

Protein Stability If adding tannin to a white wine before bottling causes a flocculate, that wine is likely to develop a haze. Should this occur, trial fine with tannin and bentonite and retest before bottling

Protein, Albuminous See Albumin

Protein, Collagenous See Collagen ; See Gelatin.

Pulpitre The "desk" which the widow Cliquot is said to have invented. It is used in Champagne making to hold the bottles during remuage.

Pyroligneous Acid The distillate of wood from which is obtained methanol

Pyruvic Acid The compound two away from alcohol in the fermentative pathway. It is a three-carbon molecule derived from glyceric acid which is oxidized to acetaldehyde - the precursor of alcohol.

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