Wine for Normal People: Ep 357: The Role of Alcohol in Wine

Ep 357: The Role of Alcohol in Wine

Jan 11, 2021

It’s the first show of our 10th year! WOW! And for our double digit birthday, this time we bring you a super dorky one that is so important to understand in wine. I have already professed it the dorkiest show of 2021, and I’m pretty sure I can’t top this so – Voilà!

First we have some fun, and challenge you to follow the three wine resolutions/challenges I’ve set forth! They are so easy, even I can keep them:

Have a wine from a region you’ve never heard of or had before! Expand your palate, do a little research, and try something totally new.
Have wine from a region that you have hated in the past. Wine is constantly changing, especially with climate change so a region you may have thought was yucky in the past, may very well have turned into your next favorite wine hub!
Drink more of the wine you love but always forget about! We all have one of those. When you get it you say to yourself, “why don’t I drink more of this? It’s so great!”

Here are the show notes on the role of alcohol in wine:

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Alcohol levels are largely determined in the vineyard:

Sugar is converted to alcohol during fermentation, so sugar levels in a vineyard are essential to determining how much potential alcohol a wine can have. From véraison (when grapes start to get color) to ripening, grapes accumulate glucose and fructose.
How much sugar depends on the vineyard conditions-- light, water, vineyard management are important
- Cooler climates, elevation, north-facing slopes yield lower potential alcohols
- Irrigation matters in determining sugar levels –some studies show glucose and fructose is higher in irrigated vines than non-irrigated ones (see Beverages Journal below, Imbibe Magazine)
- Vineyard practices like canopy management (chopping off leaves - plant doesn't absorb as much sunlight) or green harvesting (cutting grape bunches before they ripen, can focus on ripening the few that are left) help increase or decrease sugars.
  - We discuss the idea of phenolic ripeness and how that quest for flavor has led to higher alcohol levels
  - We also discuss how early picking, which seems like a natural solution, can lead to higher acid levels, less complexity, sometimes green notes in the wine – often just LESS GOOD flavor!

Alcohol in winemaking (how it gets into wine):

Yeast convert fermentable grape sugars to alcohol either from ambient yeast or by inoculated yeast.

Sugar + Yeast = Alcohol +Carbon Dioxide (+heat)

Potential alcohol (often measured by must weight) is how much sugar is available to the yeast in the grape must.
- if you don’t have enough, you can chaptalize with cane or beet sugar to raise alcohol levels (this has NOTHING to do with sugar in a wine, only with raising alcohol during fermentation)

During fermentation/maceration: Alcohol produces esters by working with the organic acids in the very acidic fermenting juice.

alcohol + acid = ester

Yeast play a big role in alcohol production, obviously. When yeast make alcohol, they kill themselves and other strains take over to finish the fermentation
- Wild fermentation can help restrain alcohol levels, but is less predictable
- Alcohol tolerance in yeast has increased, so yeast are more efficient and create higher alcohol levels in wine (discussed in our Underground Wine Event Virtual event by Stu Smith of Smith-Madrone)

Mark Smith, CC BY 2.0, https://creativecommons.org/licenses/by/2.0

Alcohol is a strong solvent so it can extract stuff out of the grape must (mushed up grape soup after crush)
- Bitter and astringent notes from seeds, skins, stems come out as alcohol levels increase, so winemakers have to be careful not to over-extract bitter compounds when the alcohol levels are high at the end of fermentation.
  - Cold Soaking can help: The wine stays at -10˚C for up to one week, so anthocyanins can come out without the bitterness.

Other benefits of Alcohol in winemaking
- Alcohol is anti-microbial
- Alcohol is a preservative during the wine maturation process.

Alcohol Measurement:

Alcohol by volume (ABV): milliliters of alcohol present in 100ml of wine expressed as a percentage.
Wines range from 5% - 25% alcohol. Factors like climate, grape variety, and winemaking play a role
What’s low, medium and high alcohol levels: My Judgement
- Low Alcohol: Under 11.5%, and are often sweet and light – German Kabinett wines, Moscato d’Asti are examples
- Medium Alcohol: 11.5 -12.5%
  - Medium-low: 11.5% - 12% ABV – Lambrusco, some Loire whites, some German and Austrian Whites, some northern Italian
  - Medium- 12.5% - 13.5% -- This is about the average for dry wines in Europe. Bordeaux, Bourgogne, Champagne, Barbera, Nebbiolo, Rosé, many Chilean wines are in this range
- High Alcohol—14%+ -- Nearly all New World Wines, many Spanish and Portuguese reds, Argentinean reds, Southern Italian wines, some southern French wines
- Fortified/VERY High Alcohol – 15%+ Usually fortified but can just be really ripe and not de-natured

The Perception of Alcohol:

Alcohol activates smell, taste, and feel (the burn) receptors

We perceive alcohol as a combo of sweet and bitter taste and the burning sensation (similar to a chili pepper) and some of this is genetic -- some people perceive alcohol as sweetness, some as more bitter (also has to do with concentration of alcohol:
Body: viscosity, fullness are directly related to alcohol content
Alcohol amplifies astringency, bitterness and acidity. Higher residual sugar is often used to counter this issue
there is no predetermined alcohol level that will create balance, this is the ART
VA: lots of alcohol means it can seem vinegar like

Alcohol Levels and Taxes:

For the wonks among us, we discuss how alcohol is taxed in the US, UK, EU and Canada. You may be surprised at how it’s calculated!

We wrap with some interesting ways winemakers reduce alcohol in wine

We reiterate the importance of getting it right in the vineyard
Humidification/ watering back: is a very common practice. You add water and it dilutes alcohol (and flavor)
Semi-permeable membranes to separate alcohol from wine
Reverse osmosis: wine passes through a membrane to strip it of ethanol. It is performed at low temperatures and aims to change only the wine alcohol content, and it usually results in 1-2% reduction. It is cheap, but it has been found to reduce complexity, mouthfeel, and affect aging in red wines.
Spinning cone column: uses centrifugal force and steam, to separate water from alcohol. The water is then recombined with the color, flavor, and tannins and poured back into the wine to dilute the alcohol while keeping flavor. This is very expensive yet effective

Source: Flavourtech

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