From Vine to Bottle at Stone Hill Winery
Photos by George Denniston for Stone Hill Winery
Stone Hill has three state-of-the-art presses to extract the juice. The presses were built in Germany by Willmes GmbH and are considered the finest made presses in the wine industry. The presses are a range of sizes to allow for optimum processing of varying lot sizes. The largest press holds up to 30 tons of grapes while the smallest only holds four tons.
The press is a large cylindrical container with a rubber membrane affixed to its interior walls. Periodically bisecting the press cylinder is a series of circular, perforated drain channels. Once the press cylinder is filled with the mix of grape skins, seeds and pulp, the rubber membranes are gently inflated with air pressure to slowly extract the juice out through the drain channels to a collection basin. After the pressure is maintained for a few minutes of juice draining, the press will deflate and rotate in order to redistribute the must and then begin the cycle all over. The whole process of pressing will take approximately two to three hours for each batch.
The real key to quality is to extract the juice very gently with minimum pressure. Rapid, high-pressure extraction of the juice would extract greater amounts of phenolic compounds from the grape skins resulting in harsh, bitter wine
During the press cycle, the press will go through a series of gentle pressure increases. With white and rosé grape must, approximately 2/3 of the juice will be extracted with a 0-0.25 bar of pressure. This is the most delicate fraction and is referred to as the "free-run" juice. As the pressure begins to increase, the winemaker will draw samples and taste the juice. The juice will gradually change, and the winemaker will determine when to switch to the "press" juice. At Stone Hill we pump the free-run and press juices to different tanks so that we can treat each in a manner that will maximize the overall wine potential.
Stainless Steel Tanks - A Modern Winemaking Marvel
From the time the juice is pressed until the wine is bottled, most of Stone Hill's wines will be stored in modern, temperature-controlled, stainless steel tanks. Stainless steel tanks are inert and air tight; therefore, they impart no flavor to the wine and protect it from oxidation. At our main winery in Hermann, the stainless steel tanks range in size from 240 to 16,000 gallons, holding a combined total of 388,000 gallons. These tanks are used for the various stages of wine making: juice settling, fermentation, clarification, stabilization, blending, and final bottling preparations.
Once white or rosé juice is pressed, it is pumped into a refrigerated, stainless steel tank. Here it will be allowed to cold settle for 24-48 hours. During this period of cold settling, the small particles of grape pulp will settle to the bottom of the tank. When settling is complete, the cellar staff will pump the clear juice off the top of the grape sediment. The sediment on the bottom of the tank will then be filtered to recoup any remaining juice. A specially selected strain of yeast will then be added to begin fermentation. During fermentation, the yeast consume the grape sugars and convert it to ethanol. In the process, they give off carbon dioxide and heat. In order to maximize the development of the fruity aromas in the wine, the fermentation temperature must be maintained in the range of 50-65 degree Fahrenheit. Failure to control the fermentation temperature will result in stuck fermentations and the production of "off" aroma and flavor. Complete fermentation takes 10 -16 days.
After fermentation is complete, the yeast will begin to settle to the bottom of the tank, and, if left in this condition, they begin to break down releasing off aromas. In order to avoid this, the wines are pumped through a centrifuge that rapidly removes the yeast, thereby preserving the fresh, fruity aroma and flavor. Centrifuging may also be done before the wine is fermented to dryness to remove the yeast and stop the fermentation while leaving behind the natural grape sugars. This technique is used to make several of our award-winning wines such as Vignoles and Steinberg White.
At this point, the wines may be blended, fined for clarity or stability, cold stabilized to remove the natural cream of tartar crystals, and/or filtered. The winemaker has the option to employ any or all of these steps prior to bottling.
Stone Hill Chardonel is barrel fermented and "sur lee" aged. In this process, the Chardonel juice begins fermentation in a stainless steel tank. Once a healthy fermentation has begun, the fermenting juice is transferred to 60-gallon, American and European oak barrels to continue the fermentation.
When fermentation is complete, the wine is allowed to remain in contact with the yeast (the definition of "sur lee" aging). In order to prevent the "off" odors caused by yeast sediment on the bottom of a tank or barrel, the wine is stirred (batonnage) initially every four days and later every seven days, to keep the yeast in a suspended or oxidative state. The suspended yeast give off complex flavors and odors that interact with the oak extract from the barrel, resulting in a dry wine of incredible complexity. The wine will continue to be aged in this fashion for seven to eight months.
In Hermann, Stone Hill Winery's oak cooperage consist of 250 60-gallon barrels for aging the Norton, Chardonel and Port. At our Branson winery, another 160 60-gallon barrels are used for aging our Cream Sherry. Barrel aging allows the wine to extract oak flavors and tannins while allowing a minute amount of oxygen to enter the wine through the barrel staves. During the period of barrel aging, many complex chemical reactions are occurring in the wine. Typically, the simpler fruit aroma of the wine will be transformed into a much more complex aroma, tannins will soften, and flavors develop great complexity.
Stone Hill Winery uses American white oak (Quercus alba) and European oak (Quercus robur) barrels. The two different species of oak have slightly different flavor and aroma profiles. In addition, the techniques employed by the various coopers while building the barrel can have a profound effect on the taste the barrel will impart in the wine. We typically buy barrels from 4-5 different coopers to build flavor complexity in the Norton wine. The barrels are only used for three years for aging our Norton wine. One third of the barrels are new each year. After three years, the bulk of the oak flavor and odor has been extracted. The barrel will then be transferred to our Port or Sherry program where we want the slow oxidative aging the barrel offers but not the strong oak flavors of a newer barrel.
Stone Hill Winery produces approximately 260,000 gallons of wine annually. The vast majority is bottled, cased and warehoused at our Hermann winery. In 2006 we installed a new state-of-the-art bottling line in Hermann. The line is fully automated and has a top speed of 120 bottles per minute.
Stone Hill Spumante Blush and Golden Spumante are bottled daily, on a one-man line, at our Branson winery. Our bottlers in Branson will be happy to show you the operation if you stop in for a tour.
Our Blanc de Blancs and Brut Rosé are fermented in the bottle, aged in tirage, riddled, disgorged and packaged at our New Florence winery.