Introduction to Winemaking Part 5: Aging, Clarification and Bottling Dr. James Harbertson Extension Enologist Washington State University

Barrel Aging Clarification  Fining  Settling  Cold Stabilization  Filtering Bottling  Enclosures Finishing Up

Barrel Aging Barrels used for storage, and flavor additive Typical barrels hold 58 gallons (220 Liters) Barrels are expensive ($200 to $600 each)  French ($ ) American ($ ) Hungarian ($ ) Barrel aging adds vanilla, spice and smoky characters to wine Also add mouthfeel (hydrolysable tannin) Barrel Age, Origin, Size and length of contact determine the amount of flavors extracted Barrels have limited life span for extracting flavors  3 years is typical  Ranges: 5 years French, 10 years American

Barrel Aging II Barrels are made from oak heartwood Other tree types tend to overpower wine flavors European oak is made from Quercus robur, pendunculata American oak Quercus alba and 6 others of lesser imp. Oak origin changes amount rather than differences in important extractives  European:10.4% aqueous extr.solids (561 mg/L GAE)  US:6.4 % aqueous extr. solids (365 mg/L GAE) Larger barrels extract less than small barrels due to surface area to volume differences Aging can last from 6 months to 2 years Wineries typically use new and old barrels each vintage (one lot is put into new and old oak)

Barrel Management Care O 2 exposure  Top up  Tight bung 4 to 10 L lost per year regardless Contaminated barrels should be removed from winery

Clarification: Fining Fining is term used to describe the addition of an adsorptive compound that is followed by settling or precipitation of partially soluble components from wine Protein and polysaccharide hazes can be removed as well as tannin by adding fining agent that after reacting with wine will form precipitate and sink to bottom of tank. Wine can then be racked or filtered to remove precipitate.

Fining Agents Proteins used for tannin removal  Gelatin, Casein, Egg White  Proteins by-products of other industries  Only remove High MW tannin Bentonite (clay) used for protein removal  Acts as a cation exchange  Must allow clay to swell 2 days before use  Removal of as waste product a problem

Fining Agents II Polyvinyl-polypyrrolidone (PVPP) used to remove monomeric phenols  Monomeric phenols cause browning and are bitter Natural Polysaccarides (agar and gum arabic) used to dissolve colloids or precipitate them Activated Carbon used to remove color, phenolics, vitamins Copper Sulfate used to remove hydrogen sulfide  Used in conjunction with SO 2 will remove disulfides

Wine Clarification Gravitational settling is easiest form of settling  Size of particle determines length of time (larger faster than small)  Slow process Bentonite can be used to help settle wines Centrifuges used to desludge wine  Expensive and primarily used in sparkling wine operations

Cold Stabilization Potassium bitartrate has lowered solubility with high ethanol and low temperature Wines are chilled to remove potential instabilities Crystals are often used to induce precipitation Tests available to determine a wines potential to haze at a specific temperature Proprietary Stabilization Processes Available Generally use an agitating crystallization tank

Filtration Can be used in broad range of applications Large solids, small particles to microbes Filters are classified according to their porosity, nature of their filter medium or flow path Filter Examples  Diatomaceous Earth Filters  Pad Filters  Membrane Filters  Cross Flow Filter Filtration Testing and Modeling

Filter Example #1 Diatomaceous Earth Filter Diatomaceous earth (DE) (small SiO 2 particles) is used to provide structural support in a developing filter cake so solids do not clog the filter DE is continuously added during filtration Eventually the filter will clog from small particles but can last a long time Particle distribution size is variable DE (- charged) is a weak adsorbent and is saturated quickly by wine particles Generally used as rough filter to remove lees

Filter Example #2 Membrane Filter Generally used for sterile filtration of wine Membrane filter collects particles at surface pores Membrane is made of synthetic polymer Pore size varies from 1.2 micron to 0.45 microns Sterile filtration (0.45 microns) is done ensure that microbes are not allowed to get into wine Sterile filtration is generally used for wines where RS is desired or there has been indications of spoilage by microbes

Filtration Testing and Modeling Testing is necessary because of variable colloidal content of juices and their ability to foul filters Pre-testing conditions can help to detect problems in advance and can save hours of work in doing so Test is done to determine the volume of wine that can be filtered before the filter is clogged Predicative models and computer programs are available to make filtration more effective

Bottling Bottling lines at large wineries are located on site in an enclosed space for cleanliness Mobile bottling lines can be hired to visit small wineries Wine is transferred to holding tank and treated with SO 2 Bottles are rinsed with hot water and sparged with an inert gas After filling the cork is inserted immediately with minimal head space Labels and capsules are then applied to bottle Bottling lines vary from manual operations (100 bottles per hour) to automated operations (100 of bottles per minute)

Bottling II QA Tests Small number of sample bottles used Wine is passed over a sterile filter and allowed to incubate in media Bubble tests for filter to assure against flaws

Bottling III Enclosed Bottling Line Bottle in clean enclosed space to reduce exposure to winery microflora Workers wear protective clothing and gloves Can run year round in large operations

Enclosure Troubles Cork taint caused by trace amounts of compound left by microbial breakdown of cork in the presence of cleaning agents Cork taint aroma from trichloroanisole (TCA) About 5% of wine has cork taint and the aroma is reminiscent of mouse or wet cardboard Rigorous sampling of cork for taint and limiting use of cleaning agents has yet to remove problem Alternative enclosures are being used

Cork vs Synthetic and Screw Caps Cork bark has been used traditionally and is semi- renewable because tree will slowly re-grow bark Synthetic corks have trouble with sealing correctly and are difficult to remove compared to cork Synthetic corks are made from non-renewable resource Screw caps have been favored because they are easy to use and seal well without worry of taint More wineries are moving to screw caps for expensive wines when it was usually only used for bulk wines