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Pasteurization
Pasteurization is process of sterilizing liquids by heating them. This process is rarely used for better quality wines.

pH
pH is a measure of acidity; the lower the pH of a substance, the higher its acidity.
Phylloxera
Phylloxera is a louse that came close to wiping out the European vineyards in the late Eighteenth Century. These vineyards were saved by grafting European (Vitis vinifera) vines onto Phylloxera-resistant American (Vitis labrusca) rootstocks. Irony abounds because the infestation came from vines imported from the United States. During the last two decades Phylloxera has once again become a problem, this time in the United States, in particular California.
Polyphenols
Polyphenols are group of organic chemicals that includes wine tannins.
Pomace
Pomace is solid residue remaining after pressing the grapes. It is composed of skins, stems, and seeds.
Powdery mildew
Powdery mildew, also known as oidium, is a fungal disease that delays grapevine growth.
Pressing
Pressing is a way of extracting juice from crushed grapes by a mechanical device. Usually pressing occurs prior to fermentation when making white wines, and after fermentation when making red ones.
Press wine
Press wine is the juice extracted by pressing the grapes. Contrast this with the higher quality free-run wine obtained without pressing the grapes. Press wine contains more tannins than does the free-run wine, and may be bitter. Winemakers often blend these two in varying proportions.
Prohibition
Prohibition was the Eighteenth Amendment to the United States Constitution that outlawed the manufacture, sale, transporting, importing and exporting of alcoholic beverages. It was ratified in 1919, and repealed in 1933. Prohibition never eliminated wine or other alcoholic beverages, or drunkenness. But it came close to destroying the American wine industry for decades. Italy, of course, never went through Prohibition.
Pruning
Pruning is the aggressive cutting back of growth on a vine, in order to control and improve its output.
Pulp
A grape's pulp is it flesh. A typical grape consists of about 75% pulp by weight.
Pump over
To pump over is to circulate the fermenting juice of red wine from the bottom of its container over the cap at the top of the must. This process prevents bacterial infestation and improves extraction of desired components in the juice. Contrast with punch down.
Punch down
To punch down is to push the cap at the top of the must down into the fermenting red wine juice in the container. This process prevents bacterial infestation and improves the extraction of desired components in the juice. Contrast with pump over.
Punt
The punt is the indentation in the bottom of some wine bottles, especially Champagne bottles. This indentation strengthens the bottles and makes them easier to stack.
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