The varieties of grapes used in producing a Champagne help determine its style. Today, there are three grape varieties used in Champagne production: Pinot Noir, Pinot Meunier and Chardonnay. Champagnes can either be single-varietal or a blend of varieties.
Pinot Noir produces rich, age-worthy wines by contributing backbone, power and grip to the wine.
Pinot Meunier is a relative of Pinot Noir and accounts for about 34% of the plantings in Champagne. The grape, for some reason, is often considered inferior to Pinot Noir and Chardonnay because of its rusticity, but it is an important component of many Champagnes, including Krug. Pinot Meunier has several notable advantages: it buds later and has better resistance to cold, thus it is able to ripen well in poor years and has better acidity. For these reasons, it is usually planted on lesser slopes. Pinot Meunier adds fruitiness to blends and displays yeastiness well.
Chardonnay buds early, which makes it susceptible to frost in the spring, but it also ripens early, which makes it a good cold-climate grape. Chardonnay gives freshness, elegance, finesse and a slightly steely character to blends.
Other grape varieties, like Petit Meslier, Arbanne, Pinot Blanc, and Gamay were once present in Champagne, but now it’s illegal to plant varieties outside of Pinot Noir, Pinot Meunier and Chardonnay. Some old vineyards with pockets of these other varieties still exist, but most have been replanted to Pinot Noir.
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In Champagne, growers are required to harvest grapes manually. The grapes are picked into small plastic buckets and transported to the press house, sometimes located directly in the vineyard to reduce travel time. The whole bunches of grapes are pressed very gently in traditional in basket presses, which yield very pure juice because the thick layer of grape skins acts as a filter for the juice. Today, regulations also permit more modern types of presses.
Most juice or must for Champagne is fermented in stainless steel vats to preserve the crisp, refreshing fruit, though a handful of producers still use traditional barrels. Krug is the only house that ferments all of its base wines in barrel. Malolactic fermentation (MLF) is commonly practiced to soften the wines and help develop aromatic richness.
After blending, the wine is bottled and a mixture of yeast and sugar is added. Bottles are then capped with crown caps like those used on old-fashioned soda bottles. This addition of yeast, known as the liqueur de tirage, produces the secondary fermentation. The liqueur de tirage is a mixture of wine, sugar and selected yeast culture. 24 grams of sugar will produce 6 atmospheres of pressure, which is most common, raising ABV by 1.5%. Adding about 14 grams of sugar produces Crémant, a less frothy style. 
The amount of aging is a third important determinant of Champagne’s quality. As the yeast consumes the sugar, it gives off carbon dioxide, creating bubbles. When no more sugar remains, the yeast dies. Under the influence of the alcohol, the yeast begins to break down in a process known as yeast autolysis.
Before putting the final cork in a bottle of Champagne, a mixture of sugar and grape juice, the dosage, is added to regulate the flavor and give a consistent style from year to year. A lower dosage with less sugar will produce an austere, long-lived wine, while a more generous one will give a wine that is fuller in body and richer in aroma. Some Champagne houses do not add any dosage; these are called brut nature or brut natural.
