Maceration: The act of soaking grape solids in their juice for certain time periods prior to fermentation of the juice.

Madeira: Portuguese island in the Atlantic from which come rich, sherry-like dessert wines. These are long lasting wines and it is not unusual to find Madeira wines from vintages in the late 1800s that remain in great condition today. Just as in the case of Sherries and Vin Jaune, part of the flavour of Madeira wine comes from deliberate oxidation of the wine during aging. That also explains their longevity.

Magnum: Oversize bottle, twice the size of a standard 750 ml. wine bottle.

Malbec: One of the five major red wine grape varieties of Bordeaux and produces excellent wines in Argentina.

Malic acid: A natural organic acid that occurs in ripe grapes at relatively high concentrations. It is the second most abundant organic acid in most vinifera varieties. Tartaric acid, of course, is the primary grape acid in nearly all varieties. The tartaric is not metabolized by yeast during fermentation or by most spoilage organisms that might grow in the wine. Only the Malic portion of the acidity of grapes or wine is easily changed by microbes. See Malo-lactic fermentation.

Malo-lactic fermentation: A bacterial fermentation that sometimes occurs in new wines after the primary yeast fermentation. Malo-lactic, or secondary fermentation changes natural malic acid into lactic acid and CO2. From the wine taster's point of view, malic acid, which has a sharp flavour, is removed, carbon dioxide is given off, and the much less acidic and softer tasting lactic acid appears. This smoothes the flavour of the wine. Usually a wine that has undergone malolactic fermentation is less acidic and can take on buttery and creamy overtones, as lactic acid is the type of acid found in milk.

Manzanilla: A Sherry-like wine from Sanlucar de Barrameda, Spain, always bone dry.

Medoc: (may-doc) Red wine district within the Bordeaux region of France in which are produced many of the greatest red wines of the world.

Meritage: US terms only. A blend of Bordeaux varietals bottled and marketed under the name “Meritage” because the winemaker thought the blend was a better wine than any of the varietals alone. Meritage has special rules: Red Meritage must contain at least three of the five permitted varieties (Cabernet Sauvignon, Cabernet Franc, Merlot, Malbec and Petit Verdot). White Meritage may contain Sauvignon Blanc, Semillon and, maybe, Muscadelle or Merlot Blanc, but no other varieties.

Merlot: (mer-lów) One of the great red varieties of Bordeaux. Also produces fine red wines in California, Chile, Australia, and Argentina and in many other regions where it is often blended with its cousin, Cabernet Sauvignon. However, it must also be said that in head to head competitions, it is unusual for the best Merlot wines to rank higher than the best Cabernet Sauvignon wines.

Méthode Champenoise: Literally, "made by the Champagne method" the classic, time-consuming way to produce Champagne and many other sparkling wines. This is the traditional bottle-fermented method for producing sparkling wines, including fermenting, aging, riddling and disgorging -- all in the same bottle that will eventually reach the consumer.

Microclimate: The localized climate in a specific, small area as opposed to the overall climate of the larger, surrounding region. A microclimate can be very small, as to encompass a single vine, or cover a whole vineyard of several acres or more. Microclimates can be caused by slope of the land, soil type and colour, fog, exposure, wind and many other factors.

Mildew: Grapevine disease. Can be devastating but is usually controlled by dusting the vines with sulphur or spraying with organic fungicides. The two major types of mildew are Powdery mildew, which occurs in low humidity and Downey mildew, which occurs in higher humidity like Europe and other wine regions of the world.

Mosel: German wine river valley which produces excellent quality Riesling wines. This region is known for its slate soil on very steep cliffs. It is said, “Only Germans have the tenacity to farm the sides of these cliffs” but the resulting wines are worth it.

Muscatel: Wine made from Muscat grapes, usually sweet and usually high in alcohol.

Must: The sloppy mess that results from crushing fresh grapes (before fermentation). Includes pulp, skins, seeds, juice and bits of stem.