Winemaker's Archives -- George Troquato

Cellar Hardware: Stemmer/Crushers and Presses

Feeding grapes into a
Delta E2 Stemmer/Crusher


Interior of stemmer/crusher

While it is no secret that great wines begin with great grapes, the manner in which fruit is handled has a profound effect on quality. From the moment grapes arrive on the crush pad to the instant wines are bottled, winemakers are faced with a multitude of decisions. Knowing how to employ cellar hardware is among their most critical.

Stemmer/crushers are the first significant devices that grapes encounter on their journey to becoming wine. Whole clusters are guided into a rotating stainless steel cylinder that has hundreds of holes drilled into it. Grapes are nudged through the holes by rubber-tipped paddles attached to a rotating shaft at the center of the cylinder. The stems are pushed out by the paddles as individual grapes drop between two rollers spaced a short distance apart. Adjusting the gap between the rollers controls the degree of crushing (skin breakage).

Contemporary winemakers can choose from a variety of presses including the popular tank and membrane press. Tank presses protect grapes from air contact while the "membrane" refers to the elasticized cloth inflated to squeeze juice or wine from skins. Fully automatic and computer driven, these sensitive machines are capable of applying minute amounts of pressure. Interior drains permit juice to exit the press where it is collected and removed.

Willmes membrane press

Winemaker George Troquato applies a Delta E2 Stemmer/Crusher and Willmes UP 2500 Press according to the type of wine he is producing. Chardonnay grapes bypass the stemmer/crusher and are whole-cluster pressed at less than one atmosphere (1 atm. = 14.7 lbs./sq. in.). This gentle approach enhances aroma and flavor and minimizes astringency. The juice is chilled to 50F and settled overnight, then moved to small oak barrels for fermentation. For red wines, George likes to hand-sort and simply destem the grapes (no crushing) before moving them to open-top tanks. This whole berry fermentation maximizes flavor and color extraction while minimizing the release of unwanted bitter compounds from the skins and seeds.