The most critical time of the year is the day you pick. You have to consider how to make wine from grapes from here on. It sets the annual harvest in motion and determines the kind of wine you’ll make. As a grape grower and a winemaker, you should keep a notebook. You’ll be glad to have records in the months and years to come. Let’s start with sight, touch, smell, and taste. You want your grapes to be rich in color, not green.

Now Let’s Try to Follow the Instructions on How to Make Wine From Grapes

Before You Start to Make Wine From Grapes, You Have to Harvest the Grapes.

It’s not a secret that you can produce better wine from better grapes. The most critical day of the year is the day you pick. With this decision, you determine the character of the wine you’ll make.

 Step-by-Step Process. 

• A grape’s terroir: Effects of the season, weather, soil, mineral, time of harvest, pruning method, and acidity=quality, aroma, and flavor
  • Harvest time = grape’s level
    •  sugar(Brix)) usually > 15
  • Acid levels – Tartaric acid
  • pH
• Other harvest factors:
  • Tannin development(seed color and taste)
• De-stemming(removal of stems) depends on winemaking techniques
  • Stems and seeds = tannins
  • White wines – stems intact
  • Red wines – stems removed

We Can Make Wine From Grapes According to Varietals

There are over 10,000 documented wine grape varieties in the world. But there are certain names that are more popular. The most recognizable grape varieties are known in the wine world as international varieties.

• Over 10000 varieties of grapes in the world
• Vitis vinifera
  • Most common species of grapes
  • Almost all the European varieties
  • Every continent except Antarctica
• Vitis Silvestris: ancestor of modern wine
• Grapes Uses
  • 71% Wine
  • 27% Fresh Fruit
  • 2% Dried fruit
• Top wine production regions: Italy, France, Spain, the US, and Argentina
• Grafting Root Stock

Chemistry of the Grape

It may sound strange and make you get different friends, but all those different smells and tastes come from complex chemistry that gives each bottle of wine its unique flavors. First off, sorry high rollers, but no matter how much you paid for it, a bottle of wine is about 98 percent water and ethanol.

• 70-90% Water
• 18-25% Glucose & Fructose
• 0,3-1,5% Tartic & Malic Acids
• 0,7% Amino acids
• 0,15% Potassium
• <0,1% Esters
• <0,1% Polyphenols
• Trace Amount Vitamin A, Vitamin C

Crushing the Grapes

Everyone knows the old way of doing it. It was to dump the grapes into a container, step into the container with bare feet and start to stomp. If you prefer, you can still crush grapes with your feet, but if not, you might want to try what kind of handy machine.

• .Crushing = start the liberation of juice from the grape
• The Must = juice, skins, seeds, pulp
• Must contain molds and native yeast
  • Natural is not better
• Grape components crushed = winemaking method and variety of wine
• White Wines
  • Stems can be intact
  • Increases tannins
  • Reduce exposure to color in skins
  • Skins directly removed
• Rose Wines
  • Red-skinned grapes with minimal skin contact
  • White and red grapes
• White Wines
  • Stems usually removed
  • Contact with skin encouraged to varying degrees

Potassium metabisulfite and SO2

Potassium metabisulfite is used in wine and meat making to sterilize the must and is also used with sorbate to stabilize your wine or meat. Adding some Sulfur Dioxide(SO2) or Potassium metabisulfite protects the wine from flaws.

• Added during many stages
  • Campden tablets = 1/2g potassium or sodium metabisulfite
• Levels in the wine
  • Commercial wine = 20 to 40 ppm
  • Natural wines as low as 6ppm
    • Obie’s wines: no added sulfites; drink within 3-4 years
•  Produces SO2
  • Kills native yeast=antimicrobial
  • Anti-oxidant
    • Binds w/ acetaldehyde
    • Binds w/ anthocyanins
      •  red wine = problem
      •  Anthocyanins bind to tannins

When We Make Wine From Grapes, Sulfites Are Indispensable

Should you be worried about sulfites? No, you should not be worried about sulfites. It’s a naturally occurring thing in a lot of foods grapes have. It’s a natural part of the fermentation process.

• =K2S2O5 contributes to sulfites in wine
• = Contains Sulfites = added sulfite compounds
  • – Warning labels
    •         – 1987 US
    •         – 2005 EU
• = All wines have sulfites
  • – Sweet and White > Reds
  • – Fermentation process = 6 to 40 ppm sulfites
  • – US levels allowed = 350 ppm

Red Wine Headaches

The more likely reason you’re getting headaches from store-bought red wines and store-bought dry white wines is a secondary fermentation process in commercial wineries. This is so-called malolactic fermentation. So let me explain what this is. You ferment the grape juice into wine. A secondary fermentation process occurs with the inoculation of malolactic bacteria or happens from naturally occurring bacteria in the atmosphere. Now, that changes malic acid, which is quite a harsh acid, into lactic acid, which is a much softer milky acid. And it rounds the wine out and gives it a more excellent taste profile, but histamine is a byproduct of malolactic fermentation. So if you ever drink red wine, you get a stuffy nose, watery eyes, or a headache; that’s malolactic fermentation. Our juice arrives at the winery with lactic acid levels already elevated. So we don’t have to do malolactic fermentation, and you don’t get a headache, and you can consume as much wine as you like.

• It occurs after drinking red wines
  • little as one glass
• Usually blamed on sulfites
  • – Only 0,01% population is allergic to sulfites = asthmatics
•  Un-metabolized acetaldehyde causes headaches
• Possible other causes:
  • Histamines
  • Tannins
    • Cause release of serotonin
• Prostaglandin release
  • Cause pain and swelling
  • Strains of yeast or bacteria

Punching Down the Must

The point is to take all berries at the top and sink them into the must. That’s all. So in this way, the must and the juice will extract more elements from the berries. So that’s the point. Try to have more skin contact and extraction. We do that during fermentation almost every day, twice a day, three times a day.

• ‘Cap’ – skins, seeds, etc., top of juice – Co2
• Punching down the must
  • Juice mix with skins = color and flavor extraction
  • Introduce O2 to yeast = fermentation
  • prevent harmful bacteria growth
  • lower the must temperature
    • Preserve delicate aroma compounds
    • Increases production of esters
    • Keep yeast growing
      • Red wines 22 to 25
      • White wines 15 to 18
• Cultured, selected yeast added
  • Beginning of primary fermentation
    • 1-2 weeks
    • Converts most of the sugar to ethanol

Fermentation Reactions

Yeast, a type of fungus, converts sugar into alcohol to obtain energy, and bacteria convert sugar into lactic acid to obtain energy. There are two types of fermentation. We have ethanol fermentation and lactic acid fermentation.

• Bacteria or yeast consume one compound and excrete different products
  • Fruit(sucrose/fructose/glucose) + Yeast = Alcohol Ethanol
  • Milk (lactose) + Bacteria = Cheese
  • Flour(sugars) + Yeast = Bread
  • Ethanol + Yeast = Acetic acid(Vinegar)

Sugars

Sugar’s scientific name is sucrose. It’s not made in a lab or a factory but created by mother nature and found naturally in all known plant life on the planet. When plants absorb energy from the Sun, water from the soil, and carbon dioxide from the air, they create sucrose through a process called photosynthesis. Sucrose is the starting point for the starches and fibers found in plants. The sugar in your sugar bowl is naturally found in these fruits and vegetables.

• The sugar level in wine = Brix
• 1.0 Brix = 1% Sugar = 0.55% EtOH
• Sugar level = alcohol content
• Sugars = 1 fuel fermentation
• non-fermentable sugars
  • Arabinose, Rhamnose, and Xylose
  • Still present after fermentation
  • No wine is ever completely ‘dry’
• Chaptalization: Sucrose added to boost fermentable sugar content – boost the alcohol content
  • 17-18% alcohol highest level W/O added sucrose

Fermentable Sugars

Common knowledge is that glucose is the formal name of sugar, and fructose is the official name for fruit sugar. This isn’t true. As we know it, table sugar, or sugar, is a one-ratio chemical combination of glucose and fructose known as sucrose. This is different from what’s scientifically known as sugars because sugars are biochemical compound that’s a water-soluble carbohydrate that is typically sweet. So that includes so many things, including lactose in milk.

• Glucose
  • One of the primary sugars of wine
  • 1st sugar metabolized by yeas
  • It tastes < sweet than Fructose
  • % Glucose beginning of ripening of grape(>5x Fructose
  • At harvest, glucose = Fructose
• Fructose
  • Over-ripen grapes > Fructose
  • Twice as sweet as glucose
    • Important for dessert wines
• Sucrose
  • Minimal in wine, except champagne and sparkling wines

When We Make Wine From Grapes, Alcohol – Ethanol Is the Result of Fermentation

Alcohol. Alcohol or sometimes called ethanol fermentation. Because when we talk about drinking alcohol, we’re talking about ethanol. As you might guess, ethanol fermentation is the process by which alcohol is produced and things like bread. It’s used in baking a lot.

• Alcohol content limited to 18% w/o sucrose addition
• During fermentation. >9% Alcohol needed to prevent bacterial growth
  • Mother of Vinegar(Acetobacter)
• Target alcohol = 13% Alcohol (24 Brix)
• Final Ethanol Content varies by variety

Pressing the Grapes

The basic theory behind a winepress is to divide the fermented wine or juice (depending on if you’re doing whites or reds) from the skins, seeds, and pulp that make up the grape’s solid components. This is done by squeezing because centrifuge or other similar processes aren’t recommended for this purpose.

• Pressure removes the juice from pulp and skins
• Gains 15-30% more juice
• Pressed juice has lower acidity (higher pH) than drained juice
• Red wines pressed after fermentation
• White wine pressed before fermentation
• Pressing releases different compounds from layers of the grape
• pH adjusted(3.0-3.7)
  • Tartaric or Malic Acid
  • Prevents bacterial growth
  • It gives a tart flavor or zing
• <1Brix before pumping into the barrel
  • Sweet wine <1Brix
    • Stabilized with Potassium Sorbate
• Bubbler at the top of the barrel to release Co2

Chemical Anatomy of the Grapes

Grape anatomy is essential to any wine production. The wine has been produced for thousands of years, and it’s all because of this tiny little grape. It’s perfect for any wine drinker to understand why the grape is essential. The main reason you’re drinking wine is that of the grape.

• Seeds and Stems(Optional Inclusion)
  • Tannins
• Skin
  • Anthocyanins
  • Quercetin
  • Reservatrol
  • Tannins
  • Catechins

Grape Skin and Seed Compounds

You have two phenolic compounds that are located inside the skin of the grape. You have anthocyanins saying, and then you also have tannin. Anthocyanin is the phenolic compound that gives red wine its color. Red wine will not get its color without the chemical or the phenolic compound anthocyanin. If you don’t have skin contact when making the wine, then that red grape has white juice.

• Plant polyphenol
• Binds and precipitates proteins and other compounds
• Three types: hydrolyzable, condensed, and complex
• Bad tannins (skins, seed, and stems)
  • Don’t polymerize
  • Produce bitter taste = astringency
• Beneficial Tannins(Oak barrels)
  • Preservative
  • Wine clarification(Fining agents)
    • Proteins bind to tannins
    • Clarify wine: egg whites, gelatin, bentonite
  • Young Oak barrels = more tannins
• Red wines(>tannins) pair with meats = hydrolyzable tannins
• As tannins age – they lose binding
  • fall to the bottom of the bottle
  • wine mellows

Grape Skin and Seed Compounds: Catechins

Flavanols, or Catechins, with flavones such as luteolin and flavonols such as quercetin, are a subgroup of flavonoids. These flavones are among the most general in the world. Together with anthocyanins and their oxidation results, proanthocyanidins and Flavanols are the most common flavonoids in human food intake.

• Flavanols
• Also found in chocolate
• React with tannins to make primary flavor components in wine
• Larger flavanol – tannin complexes – mellow
• Smaller flavanol – tannin complexes – bitter
• Concentrations in red wine 10mg/L to 250 mg/L
  • Lighter-bodied wine > catechin content

Grape Skin and Seed Compounds: Anthocyanins

Anthocyanins don’t contribute a lot to the taste of wine. But they play a significant role in tannin retention and aging. We have to know that anthocyanins readily polymerize with tannins. There is an intimate association between wine color and anthocyanins. The systematic investigation into this miracle has yielded a complicated set of interactions that contribute insight into wine’s color resistance.

• Water-soluble pigments of red, purple, or blue (pH)
• Flavenoids
• Antioxidants
• Odorless and almost flavorless
• Polymerize with tannins
• Important in tannin retention and aging of wine
• Five groups of anthocyanins and their presence depended on the varietal of grape and wine
  • >  free hydroxyl groups = blueness
  • > methyl groups = redness
  • Malvin group – red grapes

Grape Skin and Seed Compounds

Semena so velika koncentrirana območja, na katerih se hrani tanin. Če ne želijo dodatnega tanina pri pripravi vina, bodo pri pritiskanju dejanskega grozdja previdni, da ne bodo zdrobili semen. Če zlomite semena, boste dobili neželene čreslovine o koncu vina. To bo dalo tisto grenko, trpko lastnost. Veliko vinarjev se bo odločilo, da jih ne bodo vključili v svoje vino.

• Quercetin
  • Flavanoid
  • Antioxidant
  • Found in the skin of the grape
  • React with anthocyanins
    • deeper vibrant color
• Resveratrol (3,5,4-trihydroxy-trans-stilbene)
  • Phenol produced by plants when under attack by bacteria and fungi
  • Found on the skin of the grape
  • The antioxidant works in conjunction with Quercetin
  • Reported health benefits
• Gallic Acid: Phenolic compound
  • Antifungal and Antiviral compound
  • Found in seeds and from exposure to new oak
  • 10 – 100 g/L in wine
• Succinic Acid: Dicarboxylic acid
  • Considered flavor component
  • Salty, bitter flavor in wine elsewhere for sweetness
  • React to form esters
  • Acid + Ethanol = mono-ethyl succinate(fruit aroma)
  • In grape and by-product of alcohol and sugar rxn
• Caffeic Acid and Caftaric Acid: Cinnamates
  • The yellow-gold color in white wine
  • Esterification rxn; Caffetic Acid + Tartaric Acid = Caftaric Acid
  • Oxidation > reaction
    • Presse wine has little to no Caftaric Acid

Grape Flesh Compound: Acids

Acid is an essential part of the winemaking process and is an integral part of the overall wine experience. Acid naturally exists in fruit and grapes, and so obviously, it’s going to exist to some degree in wine. Acid is a way of balancing out sugar, and so you, a winemaker, will do certain things to wine to help control things like sugar and acid in general. Both white and red wine has about the same acidity level, but wine acidity levels vary from different parts of the world.

• Acids are important in winemaking and finishing the wine
• Primary Acids in Wine
  • Malic Acid
  • Tartaric Acid
• = Other Acids in Wine
  • Acetic Acid
  • Ascorbic Acid
  • Butyric Acid
  • Citric Acid
  • Lactic Acid
  • Sorbic Acid

Grape Flesh Compound: Tartaric Acids

Tartaric acid is an organic acid. Its color is white. It appears as crystalline. It occurs naturally in various plants, especially in tamarinds and grapes. Tartaric acid is one of the essential acids discovered in wine. It is used as an antioxidant and is added to different foods to give a sour taste. Tartrates are salts of tartaric acid.

• The most important acid in wine
• Maintains chemical stability of wine
• Influences Taste and Color
• Grapevines – few sources of high natural concentration
• Majority of acid = potassium acid salt(cream of tartar)
• During fermentation, acid binds with pulp debris(lees), tannins, and pigments
• Acid crystals can precipitate out
  • Wine Diamonds
  • Cold stabilization precipitates crystals

Grape Flesh Compound: Malic Acids

When you pick the grape, you’ve got a certain level of malic acidity, and in some vintages, it has dropped out more than others, and then once the grape comes into your cellar, you could have too high malic acid. Of course, too much or too little is never the best.

• One of two Primary Acids in Wine
• Carboxylic Diacid
• The bitter, tart taste
• Associated with green apple flavor
• Riesling = high malic acid
• Cooler growing conditions > Malic acid
• Decreases as grape ripen
• Low malic acid = flat taste
• High malic acid = sharp taste

Other Acids

Acid is one of the critical elements that give the wine its character. There’s only a little bit of acid by volume in a bottle of wine, usually less than 4%. Compared to water, alcohol, and acid are the two most significant components in a wine. The acids in a bottle can seem like small stuff. But a little goes a long way here, as in many things. That 1/2 to 3/4 of a percent of acid in the bottle contributes a big way to the wine’s longevity and age-worthiness, how well it goes with food, and the general pleasantness of wine.

Lactic Acid

• Controlled by the winemaker
• Milder than tartaric or malic acid
• It creates a milky flavor
• Rxn Lactic acid bacteria(LAB) and Malic acid
• Chardonnays and other white wines
• Some LAB histamines cause RWH

Citric Acid

• Very small quantities in the wine
• Supplement for sucrose addition

Acetic Acid

• Produced during or after fermentation
• Vinegar taste above 300 mg/L
• Acetobacter

Ascorbic Acid

• Vitamin C
• Found in young grapes
• Lost to ripening
• Added with SO2 as an antioxidant(EU limit 150 mg/L)

Butyric Acid

• Bacteria causes wine fault
• It smells like rancid butter or blue cheese

Sorbic Acid

• Used as a preservative

Chemistry in a Glass

You can pay for wine a lot, but a bottle of wine is almost 97 percent water and ethanol. The remaining pair percent makes wine taste like wine, and more, makes a shiraz taste different from a pinot noir explicitly.

• 70-90% Water
• 6-23% Ethanol by Variety
• 1-3% Pectins, Proteins, Acids
• 1% Vitamins and Minerals
• 1% Polyphenols, Flavenoids, Tannins, and flavor compounds

Aging the Wine: Oak Barrels

The French oak fermentation tanks for the tow colon project began approximately 170 years ago in the forest in the center of France. Oak trees are grown for 150 to 200 years at optimum maturity. They are harvested at optimum maturity and aged for five years in the natural elements of sun, wind, and rain. The lengthy aging is key to adequately preparing the wood, eliminating any green or sappy character.

• The average age of a French Oaktree used for wine barrels is 170 years old.
• Two major origins for Oak barrels
  • French and American
• Seasoning
  • French oak is traditionally aged or seasoned for two years
  • American oak kiln-dried
• Harvest
  • French Oak is split
  • American Oak is sawed
    • Ruptures xylem cells = release of lactones
• Flavor: American Oak > French Oak
  • 2-4x > lactones. vanilla
• First widespread use – Roman Empire
• 400 species of Oak
• 20 species used for wine barrels
• One tree = 2 barrels
• 5% of the trees used for barrels
• Oak barrels are the source of tannins
  • New barrels = high tannins
  • Green oak = bad tannins
• Porousness: oxidation and evaporation
  • 5-6 gal loss (59 gal barrel)
  • Angel’s Share
• 5 vintages before the oak character absent
  • staves sanded to open oak
  • Oak strips added to impart aroma

Other Flavor and Aroma Influence of the Barrel

The Bordeaux barrel holds 225 liters.  Inside this barrel that will contact the wine is composed of a shell and two heads. The shell is toasted on the inside. The heads are generally not toasted. This means that the wine is in contact with different styles. So as the wine infuses in contact with the two square meters of wood, it will contact different toast intensities.

• Toasting – exposure of oak barrel to fire and high temperatures
  • Reduces lactones (fresh oak aromas)
  • Increases vanilla and caramel aromas
    • Vanillin
    • Furfural
    • 5-Methyfurfal
  • High toast levels = spicy and smoky notes
    • Eugenol and Isoeugenol(spicy)
    • 4-methyl guaiacol (spicy and smoky
    • Guaiacol (smoky)
• Add oak chips to increase aromas

Racking the Wine

The two reasons to rack your wine are to help clarify your wine and prevent off-flavors and aroma from the decomposing yeast. The 1st rack should be about 5-7 days after pitching yeast. It is to remove the gross lees. These chunky fruit lees collect at the bottom of your fermentation vessel.

• Racking:
  • Separate the wine from the solids, ‘lees’, settled at the bottom of the barrel.
• Clearing
  • Settling of small particulates and matter in wine over time

Bottling Process

Bottling is probably the most exciting part of the winemaking process. Here are quick instructions for the homemade wine producer. First, you must ensure that your equipment and bottles are sanitized well. Then you have to attach your bottling stem and siphon. Start the flow of wine with your siphon and start filling every bottle. Insert the corks into your bottles and properly store your wine. You can do this even with a hand corker.

• Bottle Rinsing
  • Rinsed with Potassium metabisulfite
• Bottles Filling
  • Wine dispensed into bottles
• Corks are placed in the bottles
  • Headspace
• = Capsules placed on bottles
  • Heat-sealed

Bottles

There are three main bottle shapes used worldwide: Burgundy, Bordeaux, and flute bottle shapes. The Burgundy bottle is very easily recognizable for the sloping shoulders. The Bordeaux bottle, on the other hand, has a broader shoulder. And finally, the floodwater shapes the taller of the three is an elongated bottle. Of course, there are several types of bottles that are not so well known.

• Shape: traditional, cultural, or marketing
• Before, corks bottles were squat and flat-bottomed
• After corks: store on sidelong and cylindrical

Corks

How to cork a wine bottle?  We need some sterile corks and a wine bottle corker. Here you can see how to do it.

• The primary tree for corks is the Cork Oak, Quercus suber
• Trees are 25 years old before the cork is stripped from the trunks every ten years
• The trees live for about 200 years
• Cork production
  • 52.5% Portugal
  • 29.5% Spain
  • 5.5% Italy

Cork Taint

• ‘Corked Wine.’
• The Cork industry claims only 0.7 – 1.2% of cork taint
• Trichlorophenol compounds
• Found in cork and methylated by fungi
• The product is 2,4,6 trichloroanisole, TCA
• A damp, moldy odor
• A human detection limit of TCA is 1ppt
• Eliminate with synthetic corks, screw caps
  • It also eliminates the ‘POP.’

Storage

• Most modern wines are consumed within 24 hours after purchase(near-term consumption)
• Most important factors:
  • – Light: light rxn with phenolic compounds
  • – Temperature:
    • Chemical rxn’s 2x every 8 C increase
    • ideal 10 to 15 C
  • Humidity (75%): corks from drying
• Wine refrigerators or Wine cellars keep constant light, temperature, and humidity.

Health Benefits

Foods & Wine Magazine’s 8 Benefits of Drinking Wine(2007)

• Reduce heart attack rate (-30% lower risk (Harward Public Health study))
• Promotes longevity (- 34% lower mortality rate(Finnish Study))
• Lower heart disease  (Quin Mary University, London)
• Reduces risk of type 2 diabetes (-30% lower risk(Amsterdam VU Univ. Medical Center)
• Lower risk of stroke (Clot risk drops 50% (Columbia University))
• Cuts risk of cataracts (-32% risk reduction(Nature 2003)
• Cuts risk of colon cancer (-45% risk reduction-especially red(Stony Brook))
• Slows brain decline (reduced risk (Colombia University)

Calories in Wine and Alcohol

These days we’re all very interested in following a healthy eating and exercise regime. I’m often asked how many calories are in a glass of wine. There’s no easy answer because it depends on the grape varieties, where the grapes make the alcohol, and most importantly, the wine style. If it’s a drier wine style, it apparently has fewer calories than more opulent, sweeter, and concentrated wine styles. And it all changes from wine styles from vintage to vintage. So it can be quite tricky to calculate the calories in wine.

Recent studies report alcohol is not efficiently metabolized in the body.

• N= T-(7cal/g)*(0,28g/oz%)*P*X=T-2*P*X
• To calculate the metabolized calories (N):

• • N= net calories
  • T = total calories
  • X = #oz
  • P = % Alcohol

Pesticide in Wine

• Grapes: one of the ‘Dirty Dozen of produce
• 2008 Pesticide Action Network(PAN) Europe:
  • 128 pesticide residues in 40 bottles of EU
  • Low ppm to ppb range
• Studies are being conducted to find out if pesticide levels are of concern in wine
• Studies have found Hazardous levels of metals in wine
  • Exceed EPA THQ(Target HAzard Quotients)
    • Vanadium
    • Copper
    • Manganese
    • Zinc
    • Chromium
    • Nickel
    • Lead
• Worst countries for metal levels:
  • Hungary, Slovakia, France, Austria, Spain, Germany, Portugal, Greece
• SPEX CertiPrep carries a full line of Inorganic standards
  • Heavy Metal Mixes
  • Heavy Metal Standards
• UL and A2LA Stamp of Approval:
  • Certified by UL-DQS for ISO 9001
  • Accredited by A2LA for ISO 17025 and ISO Guide 34
• Inorganic CRMs for:
  • AA & GFAA
  • ICP & ICP-MS
  • IC
  • XRF
  • Classical Wet Chemistry Techniques
• Single element standards 1,000 mg/L and 10.000 mg/L concentrations
• Custom standards at almost any concentration