Introduction to Winemaking Part 5: Aging, Clarification and Bottling

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

2. Finishing Up • Barrel Aging • Clarification • Fining • Settling • Cold Stabilization • Filtering • Bottling • Enclosures

3. Barrel Aging • Barrels used for storage, and flavor additive • Typical barrels hold 58 gallons (220 Liters) • Barrels are expensive ($200 to $600 each) • French ($400-600) American ($200-400) Hungarian ($200-300) • 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

4. 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)

5. Barrel Management • Care • O2 exposure • Top up • Tight bung • 4 to 10 L lost per year regardless • Contaminated barrels should be removed from winery

6. 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.

7. 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

8. 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 SO2 will remove disulfides

9. 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

10. 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

11. 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

12. Filter Example #1Diatomaceous Earth Filter • Diatomaceous earth (DE) (small SiO2 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

13. Filter Example #2Membrane 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

14. 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

15. 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 SO2 • 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)

16. 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

17. 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

18. 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

19. 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