Sourcing your grapes - GENCO



Basic Winemaking - A Handbook

Bruce W. Hagen • September 2017

Contents

Basics winemaking – A Handbook 1

The basics: 1

What is winemaking?. 1

Basic differences between reds, whites and rosé wines: 2

Sanitation 3

Recommended alkaline cleaning products for winery cleaning: 4

Common sanitizers: 5

Cleaning and sanitizing your barrels: 6

Other ways to prevent microbial spoilage: 7

Using SO2 to ensure good quality wine: 9

The value of SO2: 9

Forms of SO2 ― free, bound, and total: 10

What does SO2 do and why you need to and add more during the wine making process? 10

The chemistry of SO2: 10

Stages of winemaking and SO2: 13

Adding SO2 and Potassium Metabisulfite: 14

Measuring SO2: 14

Ways to add SO2: 14

Factors affecting how much SO2 is needed: 15

The winemaking process - Getting Started 16

Sourcing grapes: 16

Cellar sanitation: 16

Harvest: 17

Temperature control: 18

Testing and adjusting the juice or must: 18

Adjusting °Brix: 18

Calculating how much water to add: 19

Acidity: pH: 19

Adjusting acidity (in a nut shell): 20

Common wine acid problems table: 21

The low down on adjusting pH: 21

The most common wine acid problems: 22

Making corrections: 22

Natural pH changes during winemaking: 23

Something to keep in mind: 23

Other options: 23

Problematic grapes: 24

Acidity: TA: 24

The ‘nuts and bolts’ of Adjusting TA: 24

Stemming/crushing 25

To sulfite or not to sulfite? Two options for fermenting white grapes: 26

SO2 addition: Pre-fermentation: 26

Skin contact: white and red grapes when making rosés: 27

Pressing white grapes: 27

Settling (clarifying) the pressed juice (whites): 28

Fermentation tannins for white grapes: 29

Racking (siphoning) settled juice from solids: 29

Preemptive Fining: (white juice): 30

Protein instability in white wines: 30

Other fining agents that can be added before fermentation: 31

Red grapes: Cold soak or cold maceration 31

Fermentation tannins: red grapes: 31

Fermentation: getting started 32

White grapes: 32

Red grapes: 32

Rehydrating yeasts and adding nutrition: both red and white grapes: 33

Adding the yeast mixture (red and white): 33

Yeast nutrition: (red and white): 33

Managing nutrient levels: 34

Other yeast-based nutrients: 36

Fermentation tannins (red and white fermentations): 36

Managing white grape fermentation: 37

Managing red grape fermentation: 37

Stuck fermentations: 39

End of primary fermentation for whites and Rosés: 39

Second SO2 addition (post fermentation ― (whites and rosés) 40

Aging wines ‘sur-lie’: 40

End of primary fermentation for red wines: 41

Extended maceration: optional 41

Pressing reds: 41

Malolactic fermentation (MLF): 42

Post MLF SO2 addition: 45

SO2 additions during storage and aging: 45

Limiting the loss/use of SO2: 45

Aging and clarification: 46

Fining: 47

Fining agents: 47

Racking: 49

Topping: 50

Pre-bottling SO2 additions: 50

Filtering: 51

Bottling: 51

Helpful numbers: conversions 52

Basics winemaking – A Handbook

Bruce Hagen

Introduction: This document has undergone a major revision since I introduced it last year. For me, it is still a work in progress. My intent for writing this was 2-fold: first to help me to focus on the most important aspects of wine making, and to explore a wide varieties of resources for advice, explanations, recommendations, and solutions to complex problems, etc., and second: to help GENCO winemakers improve their winemaking skills. The two most important and difficult aspects of winemaking are managing SO2 levels and adjusting acid.

There are many ways to make wine, but no single best approach. There are no rules, only guidelines and some accepted practices that have been shown by research and experience to improve success rate. What I’ve done here is to present some of the basic (time-honored, as well as science-based) practices useful in making wines that meet current commercial standards. Wine can be made without using cultured yeast, SO2, or any of the currently available fermentation aids (enzymes, tannin products, fining agents, etc., or use of high tech equipment — if that’s what you want. But unless you really know what you’re doing, the results are likely to be disappointing, to say the least. There are reason for following accepted practices, at least loosely, and areas where you have greater flexibility to be creative or to just let ‘nature’ do its thing. All of our technological advancements stem from trial and error, innovation, scientific research, and the desire to make a better wine or ‘widget’, for that matter. Some people would have you think that natural-made wines are necessarily better because they are natural, but that just isn’t so. Well, at least, I’m not buying it.

The basics:

What is winemaking? Simply put, it is the art and science of making wine. To the French though, winemakers refer to themselves vignerons or winegrowers rather than winemakers. They emphasize the cultivation of grapes for winemaking, and don’t make a distinction between growing grapes and making wine—the two are inextricably linked. Many wineries in France still use time-honored methods, but take advantage of modern technology. In other wine growing regions, like California, there are viticulturalists and winemakers. Yes, many winemakers are very involved with the growing of grapes for their wines, others not so much. There are some winemakers who strive to make wines as naturally as possible—minimal intervention. No question, they may make very fine wines that are long-lived, balanced, and often with minerality and a sense of place— terroir. While other winemakers use the latest new technologies to make big, bold, complex, well-structured, silky and opulent wines, but often overly alcoholic wines, unless adjusted downward using reverse osmosis. The question is what style do you prefer? So, it’s really up to you how you want to frame your style.

Basic differences between reds, whites and rosé wines:

▪ The pH range for white grapes for still wines is from about 3.0 to 3.5 and the range for reds is generally of 3.5 to about 3.8.

▪ The juice of both red and white grapes, with a few exceptions, is basically colorless. However, the pigments in red grapes provide the red to blue/red color that characterize red wines.

▪ Tannins, found in both red and white grapes, are readily transferred to the wine during skin contact (whites and rosés) and fermentation (red grapes).

▪ In general, white grapes and red grapes used to make rosés are chilled, de-stemmed, crushed, and pressed before fermentation. They are typically pressed within an hour or two, occasionally more, of crushing to prevent tannin and/or pigment extraction. The result is a fresh, fruity, and crisp wine. Too much skin contact, however, can result in a harsh finish or too dark a color. Limited skin contact, though, can add varietal character. French style rosés are usually pressed within a few minutes of destemming and crushing and have just a blush of color.

▪ Whites are best fermented near 60°F. The ideal range for fermenting whites is 55 to 64°F

▪ Red grapes are typically de-stemmed, crushed, ‘cold-soaked’ (optional), and the wine pressed-off the skins and seeds after fermentation. Skin contact is lengthy, so color and tannins are more intense. Red grapes must remain in intact with the juice during all or part of the fermentation process to make red wine. Tannins are important for developing structure and protecting the wine during cellaring and in the bottle. Fermentation temperatures range between 70° and 85°F. Many red fermentation may reach 90°F or higher for a short period.

▪ Grapes for Rosé wines should be harvested at a lower Brix than for red wines. For the best results, pick from about 21.5 to 22.5 for crisp, fresh, fruit-forward roses. They can also be made in the traditional method by draining off a portion of red juice immediately or shortly after destemming/crushing red grapes and then fermenting separately from the rest. The objective is to increase the skin-to-juice ratio, so that the resulting red wine will have more intense aromas, flavor, pigments, and tannins. The French call this traditional method: saignée (to bleed). Rosès can be a useful byproduct or done expressly for that style of wine.

▪ The juice of white and red grapes used for rosés are prone to oxidation, and therefore fermented in closed containers, e.g., stainless steel tanks, carboys (glass or food-grade plastic) or oak barrels and kept under an air-lock.

▪ Red must (crushed grapes) and finished wine, due to high levels of tannins from skin contact, are more resistant to oxidation than whites. Red grapes after destemming and crushing are generally fermented in open-top fermenters to allow the ‘cap’ of grapes that rises to the surface during fermentation to be punched down back into contact with the ‘wine’ below. The fermenting juice can also be pumped over the cap to keep the skins moist.

▪ Long, slow fermentation are thought to produce the best red wines. Commercial fermentation often take from 5 to 7 days to complete.

▪ White grapes are typically fermented at lower (cool) temperatures to preserve varietal fruit aromas. Whites fermented at lower temperatures may take up to 2 weeks to finish.

▪ Reds typically undergo a secondary (malolactic) fermentation (MLF) that reduces the wines acidity. Chardonnay wine, however, is often allowed to undergo MLF or inoculated with a ML culture.

Sanitation

If you’re like most home winemakers, you probably don’t clean and sanitize your equipment the way you should, or as often as you should throughout the winemaking process. That can lead to problems with your wine. Careful attention to cleanliness and detail will minimize potential problems.

Commercial wineries take cleaning and sanitation very seriously. They have strict protocols for doing both with all their winemaking equipment at the end of each cycle and the start of a new one. A lapse in sanitation can have significant impact on the quality and marketability of the final product. And they are usually fastidious about retarding oxidation and/or microbial spoilage and preventing accidental introduction of wild yeasts and bacteria during crush, cold-soaking of grapes, fermentation, MLF, practices, or afterward during extended maceration, as well as during racking, topping up, pumping, filtering and bottling.

Cleaning involves the removal of both inorganic and organic substances from the surfaces of winery equipment. Sanitation, on the other hand, is the reduction of microbes that can cause wine defects. This is not the same as sterilization and disinfection. 

Water quality can be an issue in winemaking. Most municipal water that has been properly treated to keep microorganism below harmful levels is fine to use for rinsing. Well-water may however contain high levels or bacteria that could affect your wine, unless it is properly treated. Water that has been softened, pH adjusted, UV treated and filtered is generally fine to use for rinsing. Soft water, though, may leave a residue and is not good to use for diluting must or mixing with yeast and other wine additives, like yeast nutrients, enzymes, tannins, bentonite, etc. It also has a higher sodium level that can make a wine taste salty. Bottled water that has been filtered and chlorine-free is much better to use for dilution and mixing with yeast.

Sanitation begins with keeping your cellar reasonably clean, free of debris and any working surfaces clean and regularly sanitized. Event floors should be vacuumed and moped with a disinfectant, especially at the start of crush. Wild yeast and bacteria are all around us. They are in the air, on flat work surfaces, and on all your winemaking equipment. It is not easy or even necessary to remove or kill every bacteria or wild yeast cell that might spoil wine. It is important, though, to keep their numbers low to minimize development and the production of metabolites that create off-aroma and flavors.

In general, anything that comes in contact with harvested grapes, must, and wine should be cleaned and sanitized, within reason, including your hands, which are a great source of microorganisms such as lactic acid bacteria. There isn’t much that can be done to eliminate wild yeast and bacteria on grapes, but winemakers can pick into lugs or buckets that have been cleaned of surface cleaned of debris, dirt and staining. From that point on, grapes should be transported in clean and sanitized containers. Stemmer crushers, presses and tanks, open-top fermenters, etc., should be thoroughly cleaned and sanitized. Collection buckets, funnels, car boys, stoppers, bungs, stir rods, tools used to punch downs, etc., need to be clean and relatively sterile. Literally everything that the grapes will come into contact with need to be cleaned and sanitized.

Simply rinsing winery equipment such as siphon hoses and carboys after use does not remove all of the organic material, staining, and hard to see films or microorganism. You need to use an alkaline cleaning agent to remove organic material, staining and biofilms (a slimy material containing microbes embedded in polysaccharides) that are typically not visible. Mold often grows in the residual rinse water which contains a very dilute solution of wine-based nutrient that remains following a quick rinse. It may take 3 or 4 rinses to remove all of the wine-based residue in carboys, fermenters, tanks, gallon jugs, etc., that can be slow to dry. This may result in contamination of the next batch of wine. To prevent this, use a cleaning solution to remove films and staining, followed by a sanitizer. Star San, SaniClean or Iodine-based sanitizers such as Iodophor BMP or Io Star, as well as a 10% solution of PMBS or high proof ethanol are all good sanitizers. Some cleaning agents can sanitize as well, after adequate contact time, but need to be rinsed. Scrubbing and brushing may be needed to remove stubborn residue and deposits. Avoid abrasive scrubbing pads on plastic to prevent scratching. Scratched and roughened surfaces are more difficult to clean and sanitize. Cleaned and sanitized containers like carboys and beer kegs should be allowed to drain upside down until there is no visible water. They can be stored with a paper cup inverted over the neck of the bottle, or a wadded paper towel placed in the bung hole. Other containers can be stored with the cover in place.

Recommended alkaline cleaning products for winery cleaning:

• Sodium carbonate (also called Soda ash). It’s a good cleaning agent for many surfaces, but should not be used to clean barrels because it leaches key oak compounds.

• Sodium percarbonate (Sodium carbonate peroxhydrate): a bleaching agent made by combining Sodium carbonate and hydrogen peroxide. When added to water it releases hydrogen peroxide, resulting in a foaming action. It is sold as Proxycarb or PeroxyClean. It has the advantage of dissolving tartrates and neutralizing acetic acid in problem barrels.

• Powdered Brewery Wash, (B-Bright, Straight A—special formulations) contain sodium percarbonate, sodium metasillicate, and a surfactant. They are safer than caustic cleaners and outperform them. Use 1 ounce per gallon for winery equipment. Soak equipment overnight in a PBW solution, and rinse the following morning - no scrubbing required. PBW can effectively clean items that can't be reached with a brush or sponge, and is strong enough to remove thick, difficult, caked-on organic soils. These cleaners also work well to remove labels from commercial wine bottles.

• OxyClean- Free (no fragrances added!) Contains sodium carbonate, sodium percarbonate, sodium metasillicate, and a surfactant. Good winery cleaner and sanitizer.

• One-Step-No Rinse sodium carbonate and sodium percarbonate which releases oxygen H2O2. Cleans and sanitizes. Requires two minutes of contact time, and no rinsing required! Use 1 tablespoon per gallon of water.

• Cleanskin-K (Scott) is an alkaline detergent. This potassium carbonate-based formulation also contains a proprietary percarbonate, chelating and sequestering agents for enhanced cleaning. Cleanskin-K efficiently removes wine tartar, color, proteins and organic soil. 

• Destainex (Scott) a sodium percarbonate- based cleaning agent with sanitizing abilities. Removes wine color, protein stains, mold, mildew, and biofilms from surfaces that wine will come into contact to: stainless steel, concrete, polyethylene, polypropylene, plastics, flexible hoses, glass and other surfaces.

• Oak Restorer-CW (Scott) a blend of buffered carbonate, bicarbonate and proprietary surfactants. It removes tartrate crystals, wine color, protein and organic soils from barrels using cool water (68-86°F).

• Others chemical agents: Sodium hydroxide, Potassium hydroxide, Sodium Silicate are caustic (high pH). Good for serious cleaning jobs, but they are caustic and need to be used with care to avoid skin or eye damage. Furthermore, they are not compatible with certain materials.

• TDC is a liquid acid cleaner for glass carboys and other glassware. It is unscented and comes in liquid form. Use at the rate of 1/2 Tbs. per 5 gallons of water and rinse thoroughly.

• Never use dish soaps! They are very hard to rinse and have an added fragrance that can taint any wine that comes into contact with it.

Common sanitizers:

• Star San is a common ‘no-rinse’ sanitizer for winery use. It’s made to foam, so it’s ideal for most general sanitizing duties (ex: tanks and equipment, etc.)

• SaniClean is similar to Star San, but has a low-foaming formulation — ideal for sanitizing pumps, filters, and as a final acid rinse.

• Both of the above products are acid-based sanitizers and when used at their recommended concentrations are quick, odorless, tasteless and safe for glass, stainless, and plastic materials. They also don’t need to be rinsed. When using Star San and Sani Clean there are no fumes and intermittent skin contact is not an issue.

• Ethanol: is also a good sanitizer. You can purchase high-proof ‘Everclear’ or Diesel vodka to use as a surface sanitizer.

• IO Star Iodine sanitizer: a ‘no rinse’ product used at the rate of 1 ounce per 5 gallons of water (25 ppm). Allow 1 minute of contact time to effectively sanitize equipment. Although, it has the same benefits as Star San and SaniClean there is a potential to stain vinyl tubing and plastic parts over time.

• BTF Iodophor: a ‘no rinse’ sanitizer for most equipment: buckets, kegs, tanks, vats, bottles and more. No residual taste or odor left behind, low foaming and gentle on hand. No-rinse concentrate requires only 1 tsp per 1 1/2 gallons of cool water 12.5ppm concentration and 2 minutes of contact time to be effective.

• Alpet D2: Like Star San and SaniClean, Alpet D2 is a surface sanitizer. However, because Alpet D2 contains QUAT (a residual bacterial killer) it has the added benefit of keeping a surface sanitized even when dry. It’s ideal for sanitizing work areas where yeast and bacteria are handled and winemaking additions are weighed and made-up.

• Chlorox (Sodium hypochlorite) although a good bleaching agent and sanitizer, it should never be used in the cellar or to clean or sanitize winemaking equipment. There is a real potential to cause a serious TCA taint (2,4,6-trichloroanisole) to wine that comes in contact with surfaces that have been cleaned with products containing hypochlorite (chlorine). Don't use hypochlorite anywhere in the winery or where wine is made, aged in barrrels, stored in case boxes, or areas where bags of corks or wine-making supplies are kept. There is a significant threat of taint from using a hypochlorite solution or its vapors that contact wood, wood pallets, paper, cardboard, or could conceivably come in contact with wine, case boxes or equipment used in wine-making.

Cleaning and sanitizing your barrels:

▪ Acidify a new barrel once it is has been filled with water and it no longer leaks. Change water daily until the swelling is complete. Citric acid, because of it low pH is an effective antimicrobial. Use 1T of Citric acid per 5 gal of water. After sloshing the solution around the barrel, allow it drain out, and then fill the barrel with wine.

▪ After racking: rinse thoroughly and acidify with Citric acid at the rate of 1T per 5gal. of water. Slosh, drain and refill with wine`

▪ After bottling— rinse, steam clean or fill with very hot water to remove tartates and residue ― or add Proxycarb at the rate of 4g per gal of water, fill with water and allow to stand for 2 to 4 hours. Empty, rinse and acidify (see below)

▪ If you have access to hot water, fill with hot water and allow to stand for 24 hours to remove deposits and tartrates, drain and acidify.

▪ Short-term storage: clean, fill with water and then for every liter (3.79 L per gal) of barrel volume, add 1 gram of citric acid and 2 grams of PMBS. If you prefer to store your barrels filled with a citric acid and PMBS solution drain and replace every couple of months as the SO2 dissipates.

▪ Long term storage: drain, clean, and acidify, allow to drain upside down overnight and then burn a sulfur strip every 4 to 6 weeks until barrel is dry. It usually takes burning 2 wicks until the barrels is sufficient dry and VA organisms are unable to metabolize. The standard dosage of sulfur is roughly 1/3 of a Sulfur Stick per 60 gallon barrel - roughly a 1” x 2-3” piece or a 5 gram disc (pastille). Avoid storing barrels outside or in open areas where the lead cable borer can burrow into the wood. This is a very real issue!

▪ VA - Treat any barrel that smells of VA or has off aromas with Proxycarb (4 g per gal of barrel capacity. Allow to stand for 8 to 24 hours, depending on severity of problem.

▪ After storage, add water to swell the barrel. Turn the barrel on end and add water slowly, allowing it to trickle in to the hydrate the heads and ends of the staves, one at a time. After about ~4 hrs. Turn the barrel over and repeat. Once the ends no longer leak, turn the barrel on its side and begin filling slowly. It may take a while to fill the barrel because it may lose water nearly as fast as it leaks out. But within a couple of hours it should retain most of the water. Typically most leaking subsides within about 8 hrs. Try and keep the barrel filled until any leaking stops. Continued leaking may be the result of holes created by the lead cable borer usually in the groove where the head and staves meet, or at the edge of the metal hoops. You can use a wood matchstick or round tooth pick to plug the hole, or obtain a spiel from the Beverage People or ReCoop, a barrel repair and reconditioning company in Sebastopol. I’ve had good luck stopping leaks by using barrel wax. The wax can be used to seal ‘matchstick’ plugs. I usually melt the wax using a propane torch, allowing it to plug areas where there is persistent seepage. It works best when the leaky area are allowed to dry for several hours. You can expose the barrel to direct sunlight or use a hair dryer to expedite drying. It’s not usual for some leaks to take as long as 48 hours to stop. Barrels with persistent leaks should be carefully inspected and repaired as needed. It’s a good idea to add PMBS and Citric acid to the barrel while it is filled with water for more than 24 hours to discourage spoilage bacteria.

▪ Cleaning the exterior of mold-covered barrels: apply a solution of  PMBS and citric acid in water (3 T of each in 1 gal of water).

Other ways to prevent microbial spoilage:

▪ Pick grapes into clean picking lugs, buckets, or micro bins. Use an alkaline cleaning agent, such as Proxycarb or PBW and rinse thoroughly.

▪ Wash your hands thoroughly when handling sanitized equipment and before contacting juice or wine.

▪ Do your best to clean your cellar and sanitize work surfaces.

▪ Clean and sanitize all winemaking equipment used in the winemaking process.

▪ Use the recommended rate of SO2 (35 to 50ppm) after stemming/crushing reds or pressing whites. SO2 is a strong antimicrobial agent that kills or greatly inhibits most bacteria and wild yeasts.

▪ Chemical and winemaking products used in winemaking should be dispensed using a freshly sanitized transfer spoon or measuring spoon.

▪ Use a fresh piece of wax paper to hold a chemical or material when measuring it on a scale. You can lift the paper carefully and slide the material into a clean and sanitized mixing container.

▪ Use bottled (filtered) water to solubilize winemaking products and dilute must.

▪ Use yeast nutrients to ensure that your fermentation progresses to dryness and does not stick. Wines that stick are prone to oxidation and spoilage due to low SO2 levels.

▪ When doing a cold soak, make sure the temperature of the must is reduced to less than 50 °F as quickly as possible by using enough dry ice or frozen water-filled plastic jugs. Yes, you have to clean and sanitize the plastic jugs.

▪ Maintaining adequate levels of SO2 throughout the entire process will usually ensure a defect-free wine.

▪ Adjusting pH levels of finished reds to less than 3.85 and 3.5 for finished whites, make them more stable.

▪ Keep open-top fermenters covered during fermentation to exclude flies out. They carry acetobacter bacteria.

▪ Rinse your punch-down tool after each use and sanitize it before use.

▪ Keep head-space to a bare minimum in storage containers, e.g., tanks, beer kegs or carboys. You may need to blend in another variety if you don’t have quite enough to top-up the container.

▪ Make sure barrels are tightly bunged. You should hear a ‘wosh’ sound when you break the vacuum that forms when wine evaporates from the barrel, as you remove the bung.

▪ ‘Top’ barrels every couple of weeks, or at the very least, monthly, and use an inert gas (Argon) to minimize contact with air. Excess headspace increases the loss of SO2 (volatilization) into the head space. This is lost as soon as you open the bung. Acetobacter bacteria and film yeast are more likely to develop when there is ample head space, the SO2 levels are low, and when oxygen is able to enter through a poorly seated bung or leaks in the barrel.

▪ Use a good quality wine to top with, preferably additional wine of the same variety and vintage. If you have extra wine, bottle some of it, say a case or two, after it has gone through MLF and been racked. You can use it for topping a barrel as needed, instead of breaking down containers as you need the wine. You can also use an older vintage or a compatible varietal, as long as it smells and tastes fine. Another option is to buy an acceptably good wine like ‘Two Buck Chuck’ to top with. If you buy a wine make sure that it acceptable.

▪ For best results, store wines at 60°F or less. Spoilage organisms are less likely to develop. If this is not practical, make sure that your SO2 levels are adequate and you test for free-SO2 regularly and adjust as needed to maintain a level high enough to prevent oxidation and inhibit spoilage bacteria.

▪ When cleaning stainless fermenters after fermentation, pay particular attention to the inside surface of the top of the drum and the upper portions of drum. Use a brush to make sure the thick residue of yeast and other metabolites that accumulates there during fermentation is loosened and then rinsed away. You can also turn the sealed drum on end, so the cleaning solution remains in contact with the residue to ensure adequate cleaning.

▪ Check your SO2 level following each racking. You’ll probably lose 10 to 15 ppm of FSO2 during racking, so you will need to add more SO2 to compensate for the amount that is volatilizes and to bind up with metabolites that form when the wine is exposed to air.

▪ Contrary to conventional thinking, wines with a pH greater than 3.6 only need about 30 ppm for stability. Use the standard molecular SO2 levels for wines with a pH of 3.6 and below.

▪ Clean and sterilize you bottle filler before using, and make sure your siphon hose is sanitized.

▪ Sanitize the cork compression and insertion mechanism to prevent contaminating the corks and the wine. Spray with a solution of Star-San, a 10% PMBS sol or high-proof alcohol, etc. If you drop a cork on the floor be sure to sanitize it before inserting it into a bottle.

▪ Keep you corks in sealed plastic bags and avoid handling them with your bare hands. Use disposable food-service or surgical-type gloves. At the very least, wash your hands thoroughly and refrain from touching your face or other parts to avoid contaminating them with Lactobacillus bacteria, commonly found on skin. It may be good for cheese-making but not wine!

▪ Before using a pump to transfer your wine, circulate a solution of a sanitizing agent like Star San through it for a minute or two. Even when carefully rinsed, pumps will contain some water and wine residue.

▪ A pressure washer is very effective at cleaning large equipment, such as open-top fermenters, microbins, stemmer crushers and presses. You can add a cleaner to the spray water for better cleaning.

Using SO2 to ensure good quality wine:

▪ I’ve included a lengthy and perhaps a bit daunting discussion here for wine geeks about the importance of SO2 or sulfites in winemaking. Sulfites smell like a lit match, while sulfides are smelly.

▪ The use of SO2 is really fundamental to successful winemaking. Since the 18th century, SO2 has been one of the most commonly used wine additives due to its efficient antimicrobial and antioxidant properties. When used properly and in moderation, SO2 is an efficient wine preservative and stabilizer. Although some wineries can make good wine without adding SO2, it is rather unlikely that an amateur can do so without expert guidance and some pricey equipment. Winemaking is fairly straight forward once you understand what SO2 does, how much to add, when to add it, and how to keep the levels just high enough to protect your wine. It does requires continual monitoring and testing to tell you when more is needed.

▪ SO2 (Sulfur dioxide) is commonly added to juice, must, and wine to inhibit spoilage microorganisms, prevent oxidation (browning and formation of acetaldehyde―the smell of sherry or bruised apples, and formation of vinegar, ethyl acetate, and other off-odors. SO2 preserves a wine’s freshness and fruity character by virtue of its antioxidative, anti-enzymatic (prevents browning) and antimicrobial properties. When added to wine, SO2 binds with aldehydes in oxidized wines and polyphenols (tannins and pigments). The remaining portion is said to be free to react.

▪ SO2 can be added by using Potassium Metabisulfite (PMBS) in the powder form, in a water-based solution, or as effervescent granules or tablets. Avoid the use of Sodium Meta Bisulfite

The value of SO2:

▪ Wines with little or no SO2 typically:

▪ tend to oxidize quickly —whites become more golden to brown, and reds turn brick-red to brown.

▪ lose flavor and aromas (‘flatten’)

▪ develop a sherry-like aroma (acetaldehyde) or notes of vinegar or finger-nail polish remover (ethyl acetate). Aldehydes produced during fermentation normally bind up with free SO2 in wine, preventing these off aromas from developing.

▪ are more susceptible to wine-spoilage organisms, e.g., Acetobacter, Lactobacillus, Brettanomyces, Pediococcus, and others) that can impart disagreeable odors, e.g., sherry, vinegar, nail-polish remover, staleness, ‘cooked’, leathery, earthy, barnyard, rancid, horse sweat, mousey, dirty sweat-socks, cheesy, sauerkraut, tanky or swampy etc.

Forms of SO2 ― free, bound, and total:

▪ A portion of the SO2 added to juice, must, or wine will bind up quickly with various components, and is therefore referred to as bound SO2. The remaining portion is ‘free’ or available to perform its various functions. SO2 testing measures free SO2 or how much is actually available to do work. Testing can also measure the ‘total’. By recording each addition, you can keep track of how much has been added. The concept is to add as little SO2 as possible, yet provide adequate protection of your wine. The ‘tested’ total is often not the same as the amount that has been added, as some is lost during fermentation and/or aging. ‘Bound’ SO2 is the portion that is present, but largely unavailable to do work. ‘Total’ is the sum of the free and bound SO2.

What does SO2 do and why you need to and add more during the wine making process?

▪ It inactivates enzymes that cause browning and reacts with O2 to prevent the formation of hydrogen peroxide which reacts with alcohol to form acetaldehyde (sherry-like aroma).

▪ It kills or inhibits harmful bacteria, wild yeast, including Brettanomyces, and binds up with various wine components (tannins, s, pigments, acids, sugars, solids, and aldehyde ― the precursor to vinegar

▪ It exists in both active (free) and bound forms. Once bound, though, SO2 is no longer active and can’t protect your wine. Some of it though, may become free later and bind with acetaldehyde.

▪ Some free SO2 is used up every time you rack a wine, or just remove the bung to smell it, taste it, or add something to it, because you expose the wine to O2.

▪ Eventually the wine becomes unstable because there is too little remaining SO2 to prevent oxidation or inhibit bacteria.

▪ Most or all of the SO2 you add prior to fermentation is used up (bound) or lost to the atmosphere during fermentation. Some is lost to volatilization and precipitation in the sediment.

▪ Total SO2 measured in a wine is typically less than what has been added from start to finish.

The chemistry of SO2:

▪ When added to must, juice, or wine, Potassium metabisulfite (PMBS) releases primarily bisulfite (HSO3-2) ions, a small amount of SO2 — the active portion, and an even smaller amount of Sulfite ions.

o PMBS (K2S2O5) + H2O ↔ SO2 (gaseous) ↔ SO2 (molecular)+ H2O ↔ H+ + (HSO3-) (bisulfite) ↔ 2H+ + SO3 -2 (sulfite).

o SO2 — the molecular form, exists as a gas dissolved in water, much like Carbon Dioxide (CO2) in water. The level can be as high as 6% for a wine with a pH of 3.0 and 0.5 percent for a wine with a pH of 4.0. It has powerful antimicrobial properties, inhibiting bacterial spoilage, growth of wild yeasts and bacteria, like malolactic bacteria.

o Bisulfite ― Most of the SO2 added to wine exists as bisulfite ions that don’t prevent oxidation, but bind with acetaldehyde (the precursor of acetic acid) that forms when alcohol is oxidized.

o Sulfite —the amount in wine is extremely small, except at high pH. But, sulfite is important even in minute amounts, because it can deactivate enzymes that cause browning and remove free oxygen from wine.

▪ Sulfite reacts indirectly with free oxygen in wine. In this reaction, O2 reacts with a phenolic compound, and is converted to hydrogen peroxide (H2O2). If free sulfur dioxide is present, the hydrogen peroxide reacts with sulfite, resulting in the formation of Sulfate and water: SO32- + H2O2 → SO42- (Sulfate ion) + H2O

▪ When wine oxidizes in the presence of adequate SO2, the production of H+ causes the pH to decrease and the titratable acidity to increase, as sulfite ions are used up. This effect is small but it can be significant in high pH wines and a reduction of as much as 0.1 pH is often observed when high pH wines are aged in barrels for a year or more.

▪ SO2 is in a pH-dependent equilibrium in juice or wine:

SO2 (molecular) + H2O ↔ H+ + HSO3 (bisulfite) ↔ 2H+ SO32- (sulfite)

▪ Although there is equilibrium between the 3 types of ions, the amounts are unequal and pH-dependent. For example, the lower the pH, the higher the percentage of molecular SO2. The level of SO2 decreases sharply with increasing pH.

▪ Equilibrium can shift from left to right or right to left depending on what component is being used. For example, if bisulfite binds up, some of the SO2 will shift to bisulfite and some of the sulfite converts back to bisulfite until equilibrium is reestablished.

▪ The level of free SO2 in wine is measured in parts per million (ppm). However, only a portion of it is ‘active’—in the molecular form. To ensure adequate protection of your wine, you will have target a specific free SO2 level to ensure there is enough molecular SO2 to do the job. To complicate matters, the amount of molecular SO2 will depend on the pH of the juice, must, or wine it’s added to.

▪ The molecular level reflects the amount of free-O2 needed to protect a juice, must, or wine with a specific pH.

▪ White grapes, having less tannins than reds, need a molecular level of 0.8 ppm of SO2 to ensure adequate protection during winemaking and later in the bottle. Reds, on the other hand, have much higher tannin levels and need a molecular level of only 0.5 ppm of SO2. Tannins are natural antioxidants.

▪ As a rule of thumb, target a free-SO2 level listed in the tables below, for the type of wine (red or white) and pH. Most wineries, deviate from this rule and add less SO2 listed in the charts for wines with a pH 3.6 or greater. The new thinking is that red wines with a pH greater than 3.6 only need about 30 ppm for stability. Many wineries maintain a free SO2 of 20 to 30 ppm for their reds with higher pHs. To be on the safe side, home winemakers should consider using 35 to 40 ppm to be on the safe side for wines with a pH of 3.6 or higher.

▪ You will need to add SO2 several time during the course of winemaking: before and/or after fermentation or MLF, during cellaring, and just before bottling because it gradually dissipates. That’s why testing is so important during the process. Every time you rack a wine, open the container to taste or smell the wine or add something, you expose it to air, and free SO2 is used up. Most or all of the SO2 you add prior to fermentation is used up (bound) or lost to the atmosphere during fermentation.

White and Rosé wines: maintain a 0.8 molecular SO2 level throughout the winemaking process, except for wines that will undergo MLF, and keep the pH below 3.6. For example to ensure that there is 0.8ppm of molecular SO2 in a wine with a pH of 3.2, you have add 21ppm of SO2

Free-SO2 needed for a 0.8ppm molecular level:

pH SO2 ppm or mg/l

3.0 13

3.1 16

3.2 21

3.3 26

3.4 32

3.5 40

3.6 50

Red wines: free-SO2 needed for a 0.5 ppm molecular level and keep the pH level below 3.85.

Free-SO2 needed for a 0.5ppm molecular level:

pH SO2 ppm or mg/l

3.4 25

3.5 30

3.6 30 ppm. At 3.6 and higher to a point the wine is protected by some other means*.

3.7

3.85

Red wines much above 3.85 should be acidified to lower the pH. pH and TA should be adjusted before fermentation (see Testing and Adjusting the Must below)

*Contrary to older charts, at pH 3.6 the wines need less free SO2. Clark Smith (Vinovation, and WineSmith. Personal communication). Above 3.6 SO2 binds with H2O2, a precursor of acetaldehyde, forming H2SO4 (sulfuric acid) which increases acidity. Why less SO2 is needed as pH increases above 3.6 is not understood.

Other considerations:

▪ To ensure that the free-SO2 levels remains near the required level between additions, add an additional 10 to 15 ppm. Thus, maintaining the SO2 level reds at about 45 ppm will ensure that your wine is adequately protected as the SO2 level dissipates.

▪ The tables above list the level of free-SO2 needed to keep a wine from oxidizing. Notice that the number goes up with pH to a point. So, it generally takes more SO2 to keep a higher pH wine safe from oxidation and bacterial spoilage than a lower pH wine.

▪ Lower pH wines are inherently more stable because they need less SO2 for protection and provide a less favorable environment for spoilage organisms. This is why adjusting pH is important. It’s not just a stylistic choice.

▪ Lower pH wines are generally more acidic, brighter and sometimes fruitier, while higher pH wines are softer, smoother, or sometimes flat. For red wines, a final pH of 3.7 to about 3.85 is good. It’s a good idea to do trials to see how the wine tastes at different levels of pH.

▪ Many commercial winemakers use a more moderate approach when making SO2 additions. They can do so, because they have more options and greater control over the wine-making process than home winemakers.

Stages of winemaking and SO2:

▪ Pre-fermentation: The initial SO2 addition is typically done immediately after crushing or just following pressing and before yeast inoculation. In some cases, the fermentation is initiated without adding any SO2 (see below).

▪ Fermentation: once the initial dose of SO2 has been made, it is not necessary or beneficial to add any more until after the fermentation is finished.

▪ Post-fermentation: Wines, having completed their primary (alcoholic) or secondary (malolactic) fermentation are very susceptible to oxidation and bacterial spoilage. Therefore, a second timely addition is needed to keep them stable. White wines and rosés will need more SO2 shortly after fermentation. Reds, with a few exceptions and traditional chardonnays, however, should not receive any further SO2 until they have completed malolactic fermentation (MLF). Wait until the MLF is done before making a second addition to avoid inhibiting MLF.

▪ During settling, after racking and aging: SO2 levels will continue to drop throughout the winemaking process. Every time you rack or open the container to smell, taste, or to add something, you expose the wine to air and SO2 dissipates. Barrel aging also exposes the wine to small amounts of air. It’s critical to monitor the SO2 level and adjust periodically to maintain sufficient free-SO2 to maintain the needed molecular SO2 level. To ensure that the SO2 level remains near the desired level between additions, add an additional 10 to 15 ppm. Maintaining the SO2 level at about 45 ppm (for most reds) will safeguard your wine. Containers should be kept filled, so there is little or no head space. This is particularly important for barrels because they lose an appreciable amount of wine due to evaporation. It’s also prudent to purge the air space in a contained, even when it’s small, with inert gas before resealing it. Check the SO2 levels at least monthly. Bear in mind that above 45 PPM, sulfite levels begin to affect the color and flavor of wine. At some point, the wine, if not disturbed much, will stabilize, and the drop in the SO2 level decreases.

▪ Bottling: Check the free-SO2 level prior to bottling and adjust as needed. Wines, even those that taste and smell fine, can go off quickly if bottled with insufficient SO2. The proper level will ensure that the wine will remain sound longer.

Adding SO2 and Potassium Metabisulfite:

▪ Potassium Metabisulfite (PMBS), a concentrated powder, is commonly used to add SO2 to juice, must, or wine. It can be added directly as a powder or diluted with water in the quantities needed. PMBS) powder contains 57% SO2 (Winy, an Enartis product contains 56%).

Measuring SO2:

▪ PMBS, when added to water, juice, must, or wine is measured in milligram (mg) of SO2 per Liter (L) of the liquid. There are 1000 milligrams (mg) in a gram of SO2 and a 1000 ml in a liter of water. This makes it possible to express the SO2 addition as parts per million (ppm) — parts of SO2 per million parts of juice or wine. One ppm is equivalent to 1 milligram (mg) (.001 g) in 1L of water, juice, must, or wine.

Ways to add SO2:

▪ 10 percent” stock solution ― An inexpensive and convenient way to add SO2 is make a “10 percent” stock solution made by adding 100 g PMBS to a liter of water (~34 ounces), or 75 g in 750 ml bottle. This actually produces a 5.6 or 5.7% solution because the potassium metabisulfide contains 56% or 57% SO2, depending on the product used. Make sure you check the label. Use the following amounts of the stock solution to add the desired ppm of SO2:

o 2.32 ml of a standard 10% (5.6%) PMBS solution adds 35 ppm SO2 to 1gal of must or juice. 3.32 grams increases the SO2 to 50 ppm.

o 3.32 ml of stock solution raises the SO2 level about 10 ppm in 5 gal of must or wine

o For 5 gal of must/juice use 10 ml of a standard PMBS solution to add 30 ppm, 11.6 ml for 35 ppm, 13.4 ml for 40 ppm, and 16.5 ml for 50 ppm.

o Use a pipette with bulb for safety and to make precise additions.

o Remember to stir the wine following an addition of the SO2 solution to distribute the material throughout the juice or wine.

o Use the he following table to determine how much of the stock solution to add for the volume of juice/must or wine you have.

SO2 addition: 10% (5.6%) solution (Winy: Enartis)

| | 5gal| 10 gal | 15 gal | 30 gal | 60 gal |

|10 ppm |3.38 |6.76 |10.14 |20.28 |40.56 |

|15ppm |5.07 |10.14 |15.21 |30.42 |60.84 |

|20 ppm |6.76 |13.52 |20.58 |40.56 |81.12 |

|25 ppm |8.45 |16.9 |25.35 |50.76 |101.39 |

|30 ppm |10.41 |20.28 |30.42 |60.84 |121.67 |

|35 ppm |11.83 |23.66 |35.49 |70.98 |141.95 |

|50 ppm |16.9 |33.8 |50.7 |104.39 |202.79 |

Example: to add 30 ppm of SO2 to 15 gal of wine using a standard ‘10’ percent solution use ~30 ml of the stock solution. (see below)

When using a PMBS product containing 57% SO2 to make a standard 10% solution add 3.32ml to each 5 gal to raise the SO2 level to 10 ppm, add 6.64 ml for 20 ppm, and 9.96 ml for 30 ppm.

▪ Direct powder addition:

o To add 10 ppm of SO2 to 5 gal of must or juice use .38 g of PMBS (dissolve in water) (1.9 g to add 50ppm)

o For 15 gal add 3.97 g to add 35 ppm, 4.54 to add 40 ppm and 5.68 g to add 50 ppm

▪ Foil pouches containing powdered (effervescent) SO2,

o Offer a convenient but more expensive way to adjust SO2. One advantage is that you don’t need to stir the wine as with other means of adding SO2.

o Pouches containing 2-g or 5-g of PMBS are available. The effervescent mixture helps to distribute SO2 in the wine.

o When using the effervescent form, the 2 g-packet will provide 528ppm of SO2 per gallon of juice or must. For example, if you need to treat 25 gal of must/juice divide 528 (the amount of SO2/gal in each packet) divided by 25. Therefore the packet will add 21 ppm of SO2 to 25 gal. Two 2 full packets will add 42 ppm. That’s fine for most reds or whites. For 10 gal of must a 2g packet will add 52.8ppm.

o One 2g-pkg of (Efferbarrique or Inodose granules) will raise the free SO2 level of a 59 gal barrel ~ 9ppm, at least temporarily.

o A 2 g-packet will add about 21ppm to 25 gal (about 1hL) of must in a 32 gallon fermenting bin. (This is very helpful if you use 32 gal food-grade bins to ferment in). So, two 2g pkts per 25 gal of must will provide roughly 42 ppm of SO2.

o If you divide the packages, remember that there is actually 5 grams of PMBS in a 2 g-packet ― so 2.5 g of the granules will provide 1g of SO2, enough to add 10.5 ppm to 25 gal.

o A 5 g-packet of Effergran or a 5 g Inodose Tablet will raise the free SO2 level in a 59 gal barrel to 23 ppm.

Factors affecting how much SO2 is needed:

▪ color of grape: white or red? More for whites.

▪ conditions of grapes: moldy, bird pecked, etc.

▪ temperature of grapes when harvested, crushed, and/or pressed

▪ stage of winemaking

▪ pH of the must, juice, or wine

▪ sanitation practices

▪ handling (number of rackings, topping practices, how often you expose the wine to air) bung or etc.)

▪ number and types of additions: an oak insert will introduce a lot of air, requiring additional SO2

▪ wines aged on the lees (sur lie) can get by with less SO2

▪ type of storage container used, oak barrel, glass or plastic carboy or stainless tank

▪ how often you top

▪ whether or not you use inert gas

▪ cellar temperature, etc.

17. Calculating how much SO2 to add:

▪ You can use the formula listed below to calculate how much PMBS to add, or the easy to use calculator: (make sure you enter 5.6% or 5.7 when using a stock “10%“ solution) or

Formula for PMBS addition

gal of wines x 3.785 x desired ppm = grams of PMBS to add

1000 x 0.56

▪ 3.785 converts gal to liters

▪ 0.56 is the fraction of SO2 in PMBS

▪ 1000 converts mg/L ppm to g/L

▪ A simplified version is: gal of wine x desired ppm x .0066 = g of PMBS

The winemaking process - Getting Started

Sourcing grapes:

Grapes that are moldy, bird-damaged, over-ripe, under-ripe, or otherwise of poor quality, seldom produce good wines. Buy your grapes from growers or other sources in areas known for producing the variety you want, for example, Pinot noir from the Russian River appellation. Consider vineyard practices and look at the quality of the fruit. Check to see if the vines appear healthy and properly managed.

Cellar sanitation:

▪ Basic sanitation of all winemaking equipment, including fermenters and storage containers, presses, etc., is important: clean all equipment used in winemaking to remove surface debris, dirt, staining, and residue, and then sanitize it. For more information regarding cleaning and sterilization, se the discussion above in section 2.

Harvest:

▪ Ideally, grapes should be picked when they are ripe. Ripeness is usually expressed as percent sugar or °Brix (°B). California grapes are typically picked when the sugar levels are about 23 to 26°B (17.5 to 19 for sparkling) and 21 for some ‘crisp’ and austere whites). A refractometer is usually used to check grape sugar in the field. Grapes or clusters can be collected and tested later using a hydrometer. The larger the sample, the more accurate the test. For greater accuracy, select whole clusters from different parts of the vineyard and different sides of the rows - say one cluster per every 10th vine. Place the grapes zip-lock bags and crush to release the juice for testing. The bags with their contents can be frozen and added to the fermenting juice after you’ve harvested.

▪ It’s best to pick early in the morning when the grapes are cold. Transport the grapes in food-grade ‘trash’ bins that can be cooled by adding dry ice or frozen water jugs. You can also picking lugs or a microbin. It’s also a good idea to tarp the containers while in transit and when exposed to direct sunlight. Frozen water-filled jugs should also be used if you have a long way to go or have to pick later in the day

▪ Harvest only the clusters that appear ripe and those that are free of mold. For whites ― a green to yellow or golden appearance, depending on grape variety. Most red grapes are dark navy-blue. Avoid clusters with grapes that have a reddish cast. If in doubt, taste the grapes. To determine the approximate yield of juice in gallons, divide the weight of the fruit by 15.

▪ Targeting a specific °B level is not the best way of ensure ripeness. Grapes can have a high °B and still be unripe, and grapes can be ripe, even though their sugar level is seemingly low ― say 22.5. There are many variables that influence ripeness, so relying solely on °B can be a mistake. Color and taste are better indicators of ripeness, as well as seed and stem maturity—both should be brown and the seeds should be crunchy and have a nutty flavor.

▪ Grapes are often left hanging even after they are obviously ripe in hopes of increasing fruitiness and pigment content. This can result in very high °B and low acidity (high pH and low TA, creating problems for the winemaker. First, overly ripe grapes produce high alcohol wines unless diluted with water to reduce the sugar content. Too much alcohol can make a wine taste ‘hot’ (sense of burning in the mouth). Furthermore, the fermentation may stick, resulting in a sweet wine or bacterial spoilage. Another major consideration is that pH of high Brix grapes is usually too high and the TA too low to make a good wine without having to make significant adjustments. Correcting this problem can be difficult for amateur winemakers.

▪ Wines made from grapes that are ‘ripe’ but that have reasonably good acid levels are much less problematic and more stable. Grapes harvested much above 25B°, typically should be diluted to lower the resulting alcohol level (see Adjusting the °Brix below).

▪ To estimate potential alcohol, multiply the °B by .57 (common conversion factor). For example: 26°B x .57 = 14.8%. If the °B level is 27, the resulting alcohol level will be 15.4 —very hot! If you dilute to 25, the alcohol will be 14.25%. If you dilute it to 24ºB, the alcohol will be 13.7% —quite acceptable. If you don’t dilute the must, select a yeast that can tolerate high alcohol to prevent sticking when fermenting high °B juice that has not been diluted. Overly ripe grapes are also low in nutrients essential for vigorous yeast development.

Temperature control:

▪ Warm grape are prone to microbial spoilage, particularly during the cold soak phase (see Cold Soak below). Try to pick early in the morning so the grapes are relatively cool.

▪ Warm-grapes should be cooled to 3.85)

▪ Tartaric acid can be added to high pH musts to lower pH to the desired range. Below 3.6, cold stabilization causes some of the tartaric acid to precipitate as tartrates (Potassium Bitartrate), lowering pH and TA.

▪ Adding tartaric acid will also increase TA (see below).

Adjusting acidity (in a nut shell):

▪ If TA is above 10.5, determine if the cause is excess Malate or Tartrate. Have a commercial lab determine if the cause is Tartrate. If so, proceed with the correction listed below. If not, a ‘double salt- process’ will be required (contact Enartis or Scott Labs for advice)

Common wine acid problems table:

Must/Juice Acidity Treatment Result

pH TA pH TA

High Low Tartaric acid (3.8 g/gal) ↓ ↑

0.1-.2 1.0g/L

Low High Potassium Bicarbonate ↑ ↓

2.54 g/gal 0.1 1.0g/L

High >3.6 High Calcium carbonate ↓ little change

High >3.6 High Potassium carbonate little change ↓

>3.6 High fermentation & cold stab.* ↑ ↓

3.5 and TA < 6g/L) (common in warm areas, and with extended hang-time)

▪ High pH and high TA (pH> 3.5 and TA >9g/L) (usually the result of excessive tartrate and excess potassium. Such wines may resist adjustment and you may need to seek technical advice. High malate is best remedied in the vineyard.

Making corrections:

▪ Make acid adjustments incrementally to avoid excess acidification or deacidification. After each addition, taste the juice/must and measure pH to see the result. Then determine if more acid improves or diminished taste.

▪ Tartatic acid is commonly used for high pH and low TA musts to lower pH↓ and increase TA↑ by and adding acid and increasing the H+ level.

o Add 3.8g per gal of juice/must or 1 g/L (liter) to lower pH by 0.1 to 0.2 pH units, and raise TA by about 1.0 g/L. Add the tartaric gradually to see how the must responds. You don’t want to lower the pH too much.

▪ Potassium bicarbonate (KHCO3) or Potassium carbonate is commonly used to adjust for wines with low pH and high TA. It lowers TA↓ and raises pH↑ by removing tartaric acid. This happens because it neutralizes 2 H+ and the K+ ion which increases Bitratrate precipitation, effectively removing tartaric acid. Carbon dioxide is released.

▪ Add 3.8 g/gal (1 g/L) Potassium Bicarbonate or Potassium carbonate to increase pH by about 0.1 pH unit. Make the addition gradually, say one third or one half the calculated amounts and to see how the wine responds.

▪ Below pH 3.65, Potassium Bitartrate precipitation lowers both pH↓ and TA↓. This works because potassium ions (K+) in the must combines with Bitartrate ions (HTa-) to form a precipitate (Potassium Bitartrate: KHTa). This removes tartaric acid from the juice, lowering TA↓. The additional H+ ions that are released lower pH↓. The loss of Bitartrate ions, shifts equilibrium in the reaction below to the right, to replenish Bitartrate ions lost to precipitation:

H2Ta (tartaric acid) ↔ + H+ + HTa- (bitratrate ion) ↔ 2H+ + Ta2- (tartrate ion) (↔ indicates equilibrium)

▪ Above pH 3.65, Potassium bitartrate precipitation lowers TA↓ but raises pH↑ because the equilibrium reaction shifts left to replenish the HTa- lost to precipitation, resulting in the loss of one H+ : H+ + HTa- ↔- H+ +Ta 2

▪ Potassium bitratrate does not form readily when pH is well above 3.6.

▪ Calcium carbonate (CaCO3) can also be used to deacidify wine. The Ca++ ions bind with tartrate ions, precipitating some of tartaric acid and lowering TA↓

▪ Calcium carbonate is mainly recommended for large acid (TA) adjustments of more than 3 g/L (TA above 9 g/L).

▪ Calcium carbonate provides a minimal increase in pH provides but the maximum TA reduction. It does take longer for the reaction to occur and for the Calcium Tartrate to settle out.

Natural pH changes during winemaking:

▪ Diluting high B° grape must with water reduces TA, but not pH due to the buffering capacity of the juice. Depending on the starting TA, this may be beneficial.

▪ Skin contact, which releases K+ ions, raises pH approximately 0.2 units. TA remains the same

▪ Primary fermentation causes pH to increase by 0.1 to 0.2 pH units, and TA to drop by about 1g/L as tartaric acid binds with K+ ions, forming Potassium Bitartrate.

▪ Chilling wine (cold stabilization) maximizes the precipitation of Potassium Bitartrate, lowering TA. Cold stabilization also lowers pH if it takes place below a pH 3.65, but increases pH if the medium is much above 3.65.

▪ MLF and acidity changes: pH↑ by 0.2 units and TA↓ by 1 to 2 g/L.

Something to keep in mind:

▪ Adding acid, can solve a high pH and high TA must problem, no way! Yes, it actually works. If you add 2 g/l of Tartaric acid to a grape must with a high pH of ― say 3.9 and a high TA — say 9.0 g/L, the pH may drop to about 3.55 (changes are not always linear). But as you would expect, TA would increase to 11, but because the pH is now below 3.6, tartrate precipitation will act to lower the TA to about 7 — Hallelujah! This wine, following cold stabilization could wind up with up with a pH of 3.4 and a TA of 6.3

Other options:

o Calcium Sulphate (CaSO4) is used in the production of sherry in Spain and is legal in Canada to lower the pH in wine without increasing TA

o CaSO4 + H2Ta (tartaric acid) → CaTa + SO4 2- + 2H+ • The CaTa precipitates, allowing a further ionization of these H+ ions. This lowers the pH ↓ and TA remains unchanged.

Problematic grapes:

▪ High TA musts in California typically have high levels of tartaric acid and potassium. The potassium is often the result of high ripeness stress conditions.

▪ If acid addition doesn’t help high pH and high TA wines, the problem might be lots of Potassium and tartrate or high Malic acid (cold years). Such wines are difficult to fix. You really should get technical advice from either Scott labs or Vinequiry.

▪ Problems can also result when there is too much malic acid (a low tartrate: malate ratio). You’ll need to test for this condition) and will require more drastic steps such as double-salt treatment. It is frequently linked to over-cropping, dense canopy, and low flavor and color. You may need to add Calcium carbonate (CaCO3) mixed with calcium tartrate and calcium malate to correct the problem. It will cause calcium maleate and calcium tartrate to precipitate at high pH. This is usually done by adding an excess of CaCO3 to 20 to 30% of the wine and then recombining the 2 lots. This will lower TA and pH. The wine can then be acidified with tartaric acid a necessary. Allow the salts to precipate and settle out and rack off the crystals and lees. This is a difficult process and you need expert advice.

▪ If malic acid is high, some strains of Saccharomyces cerevisiae (e.g., Lalvin 71B or Lalvin AC) can metabolize 20 – 40% of the malic acid present in a must, producing alcohol instead of lactic acid.

Acidity: TA:

▪ Total or more correctly, titratable acidity (TA) is a measure of the total amount of acidity in a wine — dissociated (ionized) and un-dissociated acids and the hydrogen ions (H+). In essence, it is the tartness of a wine. It can be measured at a wine lab or with standard equipment sold at wine-making supply outlets. GENCO offers this test as well.

▪ is expressed as grams (e.g., tartaric, malic, citric, etc.) per L (liter) of juice, must, or wine

▪ A TA of 6 g/L can also be also be expressed as 0.6% TA)

▪ TA is the best indicator of taste. The higher the TA, the tarter the wine

▪ TA ranges from 6 to 9 for most white grapes, and 6 to 7 for most reds. Most finished red wines are best when TA is close to 6. TA may be a little higher for Pinot noirs. Fresh and crisp whites are best in the range of 3.3 to 3.4 and for softer, richer whites 3.4 to 3.5

▪ High TA is a problem for red wines. Excessive acidity (tartness) accentuates astringency and bitterness.

▪ Low TA wines taste flat and are unstable

▪ Because TA will drop during fermentation and MLF, it’s a good idea to adjust red must to 7 or 7.5.

▪ If the TA of a must is higher than 7.5 g/L consider deacidification.

▪ When adjusting TA for red grape must, consider that 60 to 70% of the must is actually juice when calculating how much Tartaric acid to add.

The ‘nuts and bolts’ of Adjusting TA:

▪ Adjust TA only as needed, preferably before fermentation.

▪ Small acid corrections (around 1 g/L) can be done in wine after alcoholic or malolactic fermentation, and even just before bottling. It can, however, result in tartrate instability if cold stabilization has already occurred.

▪ TA typically drops from 1 to 3 g/L during fermentation.

▪ To raise TA, add 1g/L or 3.8 grams of Tartaric acid per gal of wine to raise the TA↑ of juice/must by 1 g/L. It will also lower pH by 0.1 to 0.2 units. (Clark Smith, Vinovation)

▪ To lower TA, use Potassium Bicarbonate (KHCO3). Add 2.55g/gal (.67g/L) or 2.35 grams/gal (.62g/L) of Potassium Carbonate (K2CO3) per gal

▪ 2.55 g/gal (.67g/L) Potassium Bicarbonate or 2.35g/gal (.62g/L) Potassium Carbonate (K2CO3) reduces TA by 1g/L.

▪ The addition of .67g/L of calcium carbonate theoretically will yield a reduction in TA of 1 g/L. This reaction commonly produces calcium tartrate, a precipitate over time.

▪ For convenience, see Acid Calculator:

▪ If the pH of a wine is greater than 3.6 after MLF, an addition of tartaric acid will lower pH without much change in TA.

▪ Adding water will reduce TA, so water should be acidified if the TA is considered low. Adding bottled water will not cause pH to change due to wine buffering. Adding acidified water will, however, cause pH to drop a bit. This may be desirable.

Stemming/crushing

▪ Once your grapes have been harvested, keep them as cold as practical until you’re ready to crush and destem them. It’s best to do so without delay.

▪ Warm grape are prone to microbial spoilage, particularly during the cold soak period if you choose to do so. (see Cold Soak below).

▪ Chill grapes using dry ice, frozen water-filled jugs, or refrigeration.

▪ Dry ice is ideal because it also releases CO2, displacing air and preventing oxidation. You can also blanket the must with argon, and then cover the fermenter.

▪ Avoid direct exposure to sunlight.

▪ Make sure that all your equipment has been cleaned and sanitized, as well as practical.

▪ Red grapes can be destemmed without crushing using a de-stemmer rather than a stemmer-crusher. In this manner, whole berries are collected and allowed to ferment. The fermentation occurs primarily within the grape skin (carbonic maceration), resulting in a fruiter and less tannic wine.

▪ Red grapes can be crushed directly into open-top stainless steel fermenters, plastic food-grade containers, or microbins, depending on the quantity of grapes. Plastic food-grade bins are convenient because they can be easily cleaned, stored, and moved around when attached to the available wheel dollies. Punch-downs are easier and the containers can easily be covered with something like a beach towel to exclude fruitflies. The solid plastic lids don’t provide a good seal against fruit flies, and you want the cover to be porous to allow CO2 and water vapor to escape.

▪ For whites, it’s most convenient to crush/destem the grapes into 32-gal white plastic food-grade trash bins. The available wheel dollies allow them to be ‘wheeled’ under the stemmer/crusher and away from it once they’re filled. Another consideration is that they can be moved around the work area to free up space as needed. Various winemaking additives such as SO2, enzymes, fermentation tannins, etc., can easily be added and mixed during skin contact.

▪ Four to five 32-gal plastic bins will handle about 1000#’s of fruit.

▪ In most cases, you’ll want to add SO2 to the holding/fermenting container immediately after crushing ― usually 30 to 40 ppm.

▪ Keep the must or whole berries chilled while measuring pH and °B, during skin contact (whites and rosés) and when cold-soaking reds.

▪ Skin contact (see Skin Contact below) enhances varietal character, but too much may increases astringency and darken color.

To sulfite or not to sulfite? Two options for fermenting white grapes:

▪ First: add the SO2 (say 40 ppm) immediately after crushing to prevent browning and oxidation. The benefit is that there will be less color and acetaldehyde formation in the wine. The drawback is that more SO2 (50 to 75ppm) will be needed after fermentation because virtually all of it will be bound up during fermentation.

▪ Second: withhold the SO2 until after fermentation. This will allow the juice to turn brown (enzymatic browning). The browning, however drops out after fermentation. The upside is that there will be less total SO2 at bottling. The downside may be a higher VA (volatile acidity—vinegary or like nail-polish remover). Harvesting and crushing the grapes when they are still cool and attention to sanitation will help minimize the formation of VA. There is also some risk of bacterial spoilage if grape quality is poor, temperature control is lacking, you have no means of blanketing the must/juice with argon or CO2, or the fermentation is sluggish or sticks. This method is most successful when the condition of the fruit is good and temperature can be maintained below 60°F, and the grapes are not overripe. Wines made in this manner may lose some fruitiness but gain in complexity. Your choice…

SO2 addition: Pre-fermentation:

▪ For home winemakers, this can be very confusing. The amount of SO2 to add should be based on the total volume (gal) of must after stemming and crushing, even though grape must contains skins and seeds which will be removed at pressing.

▪ About 30 to 40 ppm of SO2 after crushing is adequate to minimize microbial problems and retard native yeast for both reds and whites. Higher SO2 levels are recommended for warm grapes and those with bird damage and rot.

▪ Levels much above 50 ppm at fermentation are likely to inhibit malolactic fermentation (MLF), see MLF below).

▪ If the intent is to make a fresh, fruity, and crisp white, you can add up to 75 ppm SO2 to effectively inhibit MLF.

▪ Chilling your grapes will reduce the amount of SO2 needed.

▪ For each 5 gal of must:

o ~10 ml of a standard 10% (5.7%) PMBS solution will add 30 ppm SO2

o 11.6 ml adds 35 ppm

o 13.4 ml adds 40 ppm

o 16.5 ml adds 50 ppm

o 25.0 ml adds 75 ppm

▪ If you use powdered PMBS you will need to add 0.33 grams to provide 50ppm of SO2 for each gallon or 1.65g/5gal.

▪ Mix well to disperse

▪ Some professional winemakers use as little as 20 ppm of SO2 before fermentation. Home winemakers, however, would do well to use a higher rate because they generally lack the experience, technical know-how, specialized equipment, temperature control, and access to sophisticated testing equipment. Commercial winemakers also have greater control over grape quality and harvest temperature.

▪ Note: not all of the SO2 you add will remain in the finished wine, some will bind up with solids that settle out. In reds, some of the SO2 is lost to the atmosphere during ‘open-top’ fermentation and racking.

Skin contact: white and red grapes when making rosés:

▪ Crushed grapes that have been chilled to at least 60°F can be pressed immediately or allowed to sit for 2 to 8hrs before pressing. If you want to make light colored, French-style rose, press shortly after crush. Red wines can be presses within minutes of crushing if you want to make a blush wine or get the more classic pale peach or salmon color.

▪ Skin contact enhances varietal character, but too long will increase astringency and darken color.

▪ It’s important to keep the grapes cold, preferably 50°F or less during skin contact. Use dry ice, frozen water-filled jugs or refrigeration.

▪ Blanket the container with inert gas, such as Argon. Dry ice, which releases CO2, can provide additional protection.

▪ If you’re unable to chill the grapes sufficiently to protect them from spoilage bacteria, e.g., Lactobacillus, Pediococcus, etc.), you can use Lysozyme or Enartis Stab Micro M (expensive). Both can be uses in high pH wines to prevent spoilage or prevent MLF later. If you add Lysozyme you will need to fine the resulting wine with Bentonite for to prevent a protein haze from forming.

Pressing white grapes:

▪ Press after the desired period of skin contact to remove skins and seeds.

▪ The juice that flows out of the press before any pressure has been applied, and the juice that flows under relatively low pressure is called ‘free-run’. Some people prefer to keep the juice produced under high pressure, separate from the free-run juice because it can be more astringent. Bladder presses apply less pressure and there is little difference between the wine that flows early-on and the wine that flows later. It’s not until you get down to a very narrow stream and the ‘cake’ (skins and seeds) is relatively hard-packed. Another option is to use a fining-agent like Clargel (Enartis) or Colle Perle (Scott) to remove harshness and astringency from the ‘hard-press’ juice due to seed tannins. See

▪ Take your time when pressing and avoid extreme pressure. Fill your basket press about 80% full.

▪ Bladder presses should be filled to capacity, but don’t pack the grapes, even if there is only a small amount left. These can add later after an initial press to create the needed space. If you don’t have enough grapes to fill a bladder press completely, inflate the bladder to reduce the space around the bladder until the grapes just fill the void. It’s not a good idea to run the bladder press unless the basket is filled. The bladder is more likely to fail if does not inflate uniformly.

▪ Bladder pressing is gentler than a basket press—it generally results in wines that are less harsh and bitter.

▪ Bladder presses which normally use water pressure can be easily converted to using compressed air to do the work. You’ll need a few pipe fittings, and a small, portable air compressor with an accurate pressure regulator to prevent damaging the bladder and screen. That could be very dangerous, and of course, you would lose the wine or juice. You don’t need much air pressure to press the grapes — 8 to 10 pounds (per square inch will do the job.

▪ Using a basket press can be tedious and labor intensive. Although expensive, bladder presses are well worth the cost in terms of convenience and reduced labor and time involved. If you are serious about making wine, put one on your wish list, and then figure out how to pay for it. I recommend going in with several others to purchase one.

Settling (clarifying) the pressed juice (whites):

▪ Allow the solids (gross lees) in the pressed juice to settle out for at least 12 hours before racking the relatively clear juice into car boys, beer kegs, variable-capacity stainless steel fermenters, oak barrels, etc.

▪ Removal of solids minimizes harshness, astringency, herbaceous notes, and the likely development of reduced (stinky or sulfury) smells).

▪ Enzymes are commonly added during skin contact to facilitate clarification (settling of solids) with high levels of unstable protein, like Sauvignon blanc, Pinot gris, Gewürztraminer, and muscat, increase maceration (skin breakdown) to release varietal aromas, increase color in reds, and increase yield by breaking down gummy pectins. For maximum effect allow juice to settle for at least 12 hours, then rack off the thick, cloudy sediment for fermentation. This is particularly useful for grapes high in unstable proteins. You can get good clarification in 4-6 hours using (Enartis ZYM RS(P) and ZYM AROM MP, Cuvee Blanc or Color Pro. (Scott)

▪ Make sure the SO2 has been added and well dispersed before adding enzymes.

▪ Various gelatins can be used to facilitate settling, as well, e.g., Clargel, Hydro Clar 20, Hydroclar 30, Pulviclar S ( if you use gelatins you will need to counter fine with Silica gel or Bentonite). Either will facilitate the settling process.

▪ For some grapes, like chardonnay, settling occurs rapidly and without the need for additions.

▪ Consider a preemptive fining agent

▪ Bentonite or preemptive-fining agents (see Preemptive Fining below), should be added 6 to 8 hours after inoculation. it may however, inactivate an enzyme If added before it has had had a chance to work. Allow juice to settle until the solids have dropped to the bottom and the juice is reasonably clear. This may take up to 24 hours in carboys in a cool room ................
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