Finishing & Packaging Flashcards
Simplified Checklis
4 mo - 8 wks: Assemble final blend; full chemical analysis (alc, RS, free SO2, etc.)
8 wks: Final adjustments to alc, tannin, acid
6 wks: Protein stability trial and if necessary fine with bentonite
4-6 wks: Test for tartrate stability and if necessary, adjust
4 wks: check protein and tartrate stability again and adjust if necessary
1 - 2 wks: Add sweetening agents if using (i.e. grape concentrate)
72 - 48 hrs: Test filterability of wine
24 hrs: adjust free SO2
Bottling Day: Adjust dissolved oxygen and CO2
During Bottling: Check dissolved oxygen (to ensure no pick up) and SO2 levels regularly and keep samples of bottled wines for QA
Post fermentation clarification
Clarification: physical and chemical processes to make wine clear: sedimentation, centrifugation, fining, filtering
Sedimentation
If stored in cool conditions, clarification will begin naturally as suspended matter precipitates over time.
Particles of higher density than wine will fall to the bottom and wine can then be racked off.
Number of rackings depends on shape, volume, and available labor. Larger means more to avoid a thick layer.
Some premium only clarified this way. Believe it avoids loss of texture and flavor of other methods
Takes time; only suitable for prem or super. But if barrel aged, will happen naturally.
Centrifiguation
Rapid spinning of the wine to remove matter
Very effective for wines with a lot of matter
High volume wineries to spread the considerable cost of machinery
Fining
Fining agent added to speed up precipitation of suspended material. Removes a small proportion of unstable colloids (microscopic particles too small for filtering). Clarifies and helps stabilize.
Lab tests conducted to find the min amount necessary. Some can remove desirable compounds or make the wine unstable if too much used (over fining). Also may be able to remove problems like harsh tannins or browning.
Agents must have the opposite charge from the wine colloid being removed. The fining agent and colloid attract each other and form a solid large enough to be removed by racking or filtering.
Three categories: removing unstable proteins, phenolics adding bitterness or color, color and off odors
Fining Agents Removing Unstable Proteins
Must and wine contain grape derived proteins. In reds they bind with tannins precipitate and are removed with racking.
In whites and roses they can agglomerate into a visible haze if warmed. So often fined with bentonite.
Form of clay that adsorbs unstable proteins and colloidal coloring material. Minimal impact on flavor and texture. Can lead to some color loss in reds and produces large amount of sediment (so wine is lost).
Used for wine and must
Fining agents removing phenolics
These may be used with bentonite or on their own
Egg Whites: fresh or powdered form; used in high quality red wines to remove harsh tannins and clarify gently. It’s an allergen and must be declared on label in EU above limits. Not suitable for vegan
Gelatine: protein collagen extracted from pork that aids clarification, removes bitterness and astringency in red wine and browning in white wine pressings. Must be added in smallest amount necessary as easy to over fine (strip flavor and color and haze later). Not for vegan or vegetarian. Must too
Casein: Milk protein removing browning from white and clarifying to some extent. Allergin, not vegan. Must too
Isinglass: clarifies white wines giving them bright appearance. Use smallest amount possible to avoid later protein haze or fishy smell. Not vegan or vegetarian as from fish bladders.
Vegetable Protein Products: Potatoes or legumes
PVPP: Polyvinylpolypyrrolidone an insoluble plastic in powder that removes browning and astringency from oxidized white wines. Gentler than charcoal. Rarely used on reds, but can reduce astringency and brighten color.
Fining agents removing color and off odors
Charcoal: removes brown color and some off odors, easily over fines removing desirable flavors.
Can treat one batch and blend with rest to reduce impact.
Filtration
Physical separation technique used to eliminate solids from a suspension by passing through a filter medium of porous layers trapping solid particles.
Two types: Depth and Surface
Some believe filtering can negatively impact flavor and character, espec by stripping texture. So some bottled unfiltered. Others say this prevents future hazards like bacteria and yeast faults and bottles recover from the shock.
Depth Filtration
Traps particles in the depth of the filter material. Can cope with fluid with lots of particles like newly pressed wine or those with lees.
Small particles are trapped within the many channels in the filter. Doesn’t block easily but not foolproof. If too much pressure or used too long some particles can make their way through. Not absolute.
Diamatomaceous earth: most common form of depth. aka Kieselguhr. Once processed is pure silica and inert. DE is wetted and used as filter medium where wine is sucked by vacuum from the outside of a rotary drum through DE to inside.
Used for very thick and cloudy wine. Oxidative as drum exposed to air. Enclosed DE filters can be flushed with inert gas to prevent oxygen.
Range of sizes, initial investment in machinery high but cost after is small. Used DE must be disposed of properly
Sheet filtering: plate and frame or pad filters. Wine is passed through a sheet of filtering material. More sheets quicker the process. Very fine can remove yeast. Initial investment in frame, with sheets low cost. Trained personnel required.
Surface Filtration
Stops particles bigger than the pore size of the filter. Often called absolute.
Membrane: aka cartridge. catch particles that won’t go through the pores. Slower than depth as pores are smaller (often < 1 micron). Wine must be pre-filtered first or membrane easily blocked. Usually a final precaution before bottling to ensure microbial stability. Initial investment small but cartridges costly.
Cross Flow: aka tangential. Allow wine to pass through filter while uniquely cleaning the surface of filter as it works. Solid particles cannot pass through. Can work with wine with lots of particles quickly. No sheets, cartridges or earth to continuously buy. But machines are expensive.
Stabilization
Winemaking interventions that if not done could lead to undesired effects in finished wine.
Protein Stability: Fining with bentonite
Tartrate Stability: Potassium bitartrate and lesser extent calcium tartrate are harmless crystal deposits. all high vol and most small seek to prevent:
Microbiological Stability: Wines with RS could start refermenting. Can filter out yeast or add sorbic acid and SO2, which inhibit yeast. Some people can smell sorbic at low levels. Now less used.
Few microbes can survive in wine with low pH and high alcohol. Exceptions are lactic acid bacteria (where no MLF) and can happen in bottle for cloudiness. Brettanomyces can be filtered or treated with DMDC dimethyl dicarbonate aka Velcorin).
Tartrate Stability
Cold Stabilization: Traditionally, wine kept in a cold cellar through winter. Now wine held at -4C for 8 days so crystals form pre bottling and then filtered out. Requires equipment and energy to refrigerate. Colloids must be removed first as they may impede crystal formation. Only removes more common potassium bitartrate not calcium tartrate
Contact Process: Quicker, Continuous, more reliable vs cold. Potassium bitartrate added to wine, which speeds up crystallization process. Wine cooled to 0C and after 1 - 2 hours crystals filtered out.
Electrodialysis: uses a charged membrane to remove selected ions. High initial investment but lower ongoing vs cold as faster and less energy intensive. Removes both potassium and calcium ions and smaller extent tartrate ions
Ion exchange: Doesn’t remove tartrates but replaces potassium and calcium ions with hydrogen or sodium ions, which do not precipitate. Not allowed in some areas as replaces potassium with sodium which is not healthy. But resulting levels are well below legal limit.
Carbomethylcellulose: wood extract prevents tartrates developing into visible size. Widely used in inexpensive wines but not suitable for reds as interacts with tannins (rendering ineffective) and causes haze. Keeps wine stable for a few years and is cheap.
Metatartaric acid: Prevents growth of potassium bitartrate and calcium tartrate crystals reducing need for cold stabilization. But unstable and loses effect over time, espec when wine stored at high temps (25 - 30C). Best used for wines for early consumption. Quick and easy more used for reds.
Finishing Options
Adjusting SO2: Routinely checked and adjusted before bottling. Must be within legal limits. Total and free are measured, latter containing molecular part which is effective. In general amounts of free SO2 are: white 25 - 45mg/L; red 30 - 55mg/L; sweet 30 - 60mg/L.
Reducing dissolved oxygen: O2 in wine can speed up aging and reduce shelf life. Can be removed by flushing wine with inert gas to remove it. Called sparging.
Adding CO2: For some inexpensive youthful wines a small amount of CO2 is added to give a bit of spritz.
Faults
Cloudiness / Haziness: growth of yeast or bacteria from not filtering well enough (better hygiene, pre-bottling analysis, filtering). Poor filtering (pumping too hard into depth so some get through); Also from poor fining (wrong type, over fining) results in unstable proteins.
Tartrates: colorless white crystals from lack of or improper tartrate stabilization.
Refermentation in bottle: visible bubbles or spritz and/or cloudiness. Failure to stabilize or clarify properly.
Cork Taint: moldy wet cardboard smell, reduces fruit, shortens finish.
Oxidation: excessive exposure to oxygen in bottle or container. faulty bottling, poor closures, or keeping too long. Brown, loss of fruit, then vinegar
Volatile Acidity: all have it, excessive smells like nail polish or vinegar. Activity of acetic acid bacteria, inadequate levels of SO2, and oxygen exposure. Keep up hygiene, SO2, and reduce oxygen
Reduction: sulfur like odors, caused by high levels of reductive compounds. At low levels can be attractive (struck match). Can be produced by yeast under stress (low Nitrogen) or from near complete exclusion of oxygen during aging, espec when lees aging. Sometimes evolve when wine closed with impermeable screw cap.
Light strike: UV radiation and certain light wavelengths reacting with wine to make volatile sulfur compounds giving dirty drain odors. Wines in direct sun at most risk, but also florescent. Clear glass most, dark green and brown better
Brettanomyces: yeast producing off odors like animal and barnyard. Some think adds complexity at low levels. higher levels a fault reducing fruit, and making acid / tanning more prominent. Hard to eradicate (espec in wood); excellent hygiene, effective SO2 levels, keeping pH low. Treat by filtering or adding DMDC (dimethyl dicarbonate Velcorin) with inactivates.
