Wine Education

Wine Education 101: What is a Wine Flaw or Fault?

Most often, we open a bottle of wine and are greeted with wonderful aromas and flavors that delight our senses and taste buds.  However, on a rare occasion, and sometimes in home winemaking, we encounter less than pleasant aromas and tastes.  Are these considered wine flaws or wine faults – and what is the difference?  What we would most like to know is how to identify these and what causes them. 

To start with, let’s understand the difference between a wine flaw and a wine fault.  A wine flaw is an imperfection in the wine, such as a slight off-odor, minor cloudiness, bubbles or small particles in the wine.  A wine flaw might also include an imbalance with acidity/sweetness, short finish, lack of exceptional aroma or flavor, or color that is slightly off from expectations for that varietal.  These are all considered wine flaws because they are not considered normal for the wine type but they are minor enough that the wine is still drinkable

On the other hand, a wine fault is a major deviance from the normal characteristic of the wine and causes it to be undrinkable.  A wine that has developed cork taint is usually so pungent that the wine is undrinkable.  Likewise, a wine that has developed high volatile acidity (VA) will be so sharp and acidic that it too is undrinkable.  These are both examples of wine faults.

The majority of wine flaws and faults can be grouped into:  oxidation, sulfur compounds, microbiological, and environment.  These are often the result of poor winemaking practices or decisions.

Oxidation is the most common cause of wine faults, with oxygen being both a friend and foe in the winemaking process.  During fermentation, oxygen is our friend as it is vital for the yeasts to thrive and perform their job of converting sugar into alcohol.  After primary fermentation, oxygen often becomes more of a foe as it can become the catalyst for numerous reactions including a rise involatile acidity. 

Other common wine faults fall into the Sulfur Compounds category.  Negative sulfur compounds, such as hydrogen sulfide (H2S), are often associated with the olfactory flaw known as “reduced” notes.  This means that you have a high amount of negative sulfur-based compounds and not enough available oxygen in the wine to mitigate these compounds.  In winemaking, there is a fine balance between a “reductive” environment (“low redox potential”) where H2S will persist, and an “oxidative” environment (“high redox potential”) where sulfurs will often precipitate out. 

Microbiological faults are often the result of contamination with bacteria or yeasts that have not been inhibited by sufficient sulfur dioxide (SO2), which serves as an antimicrobial and antioxidant agent in winemaking.

Environmental faults are the easiest faults to avoid by simply ensuring that winemaking and storage facilities follow best practices in environmental controls such as temperature and light.

Below is a description of some of the common wine flaws (if minor) or faults (if excessive):

Oxidation Faults

Flaw/FaultSensory DescriptionCause
AcetaldehydeSmells like sherry, nutty, bruised apple or dried out straw.Wine is exposed to too much air during winemaking/bottling. Also result of film bacteria (Acetobacter) on surface of wine.  Low SO2 also contributes to this development.
Surface Yeast Contamination (Candida)Smells like musty wet cardboard, acrid, sherry.Too much headspace in container and oxygen is touching the  wine surface.  Low SO2 contributes to this development.
Acetic Acid / VA (Volatile Acidity)Smells sharp like vinegar or pickles.Typically caused by acetic acid bacteria (Acetobacter) but can also be lactic acid bacteria. Excess oxygen in the headspace of tanks, barrels or carboys. Low SO2 levels in wine. 
Ethyl Acetate / VA (Volatile Acidity)Smells sweet or fruity at low levels. Sharp, acetone or nail polish remover at high levels.Oxidation of wine along with microbial spoilage such as Acetobacter.

Sulfur Faults

Flaw/FaultSensory DescriptionCause
Sulfur Dioxide (SO2)Smells like a burnt match head; sharp/acrid, nose burn sensation.Sulfur dioxide is often added to wine as an antioxidant or antimicrobial agent.  But too much added can cause this sulfur flaw.
Hydrogen Sulfide (H2S)Smells like rotten egg. Very pungent and offensive but can dissipate with aeration.Reduction of elemental sulfur residue (from fungicide sprays on grapes, soil). Yeast stress from lack of nitrogen/nutrients or temperature stress. Lack of oxygen during fermentation.
Ethyl MercaptanSmells like garlic/onion, cabbage, vegetal, skunk. Very pungent and offensive.Existing H2S reacts with ethane to form mercaptans. Yeast metabolizing sulfur in the lees (during fermentation) or during aging from H2S that was not removed earlier.
Thiols & DisulfidesSmells like burnt rubber, garlic/onion, canned corn, cooked cabbage. Very pungent and offensive.Further oxidation and development of ethyl mercaptan (ethane or methane thiols). Difficult to treat at this advancement.

Microbiological Faults

Flaw/FaultSensory DescriptionCause
Brettanomyces 4-Ethyl-guaiacol (4EG)Smells of smoky, spicy, cloves.Contamination of Brettanomyces (spoilage yeast) due to improper sanitation and inadequate SO2 levels.
Brettanomyces 4-Ethyl-phenol (4EP)Smells like stables, horsey, sweaty-saddles.Contamination of Brettanomyces (spoilage yeast) due to improper sanitation and inadequate SO2 levels.
Brettanomyces 4-Vinyl-phenolSmells medicinal like plastic Band-aid bandages.Combination of both 4EG and 4EP also due to improper sanitation and inadequate SO2 levels.
Yeast / Ongoing FermentationSmells yeasty with visible cloudiness and fizziness.Residual sugar is left remaining in the wine with insufficient SO2 to inhibit and/or lack of sterile bottling.
Lactic Acid BacteriaSmells like a swampy, stale dishcloth or sauerkraut. Wine may appear turbid and slightly effervescent.Lactic acid bacteria (LAB) are used to convert malic acid to lactic acid during malolactic fermentation (MLF). Caution must be taken to ensure that MLF is complete before bottling or that MLF has been properly inhibited, followed by sterile filtration.
DiacetylSmells like rancid butter, buttery, butterscotch.Diacetyl is produced by the metabolism of citric acid in the wine during malolactic fermentation (MLF). Can be considered nice when this aroma is desired, but is usually not desired in red wines.
GeraniolSmells like crushed geranium leaves, floral, sweet, bubblegum.This fault occurs when lactic acid bacteria reacts with excessive amounts of potassium sorbate (sorbic acid) during malolactic fermentation.

Environmental / Other Faults

Flaw/FaultSensory DescriptionCause
Cork Taint (Trichloranisole / TCA)Smells moldy, musty (wet newspapers), and earthy like decayed wood. Fruit aromas are masked.Caused by a reaction between chlorine (cleaners) or bromophenols (fungicides) with fungus often found in corks.
Heat DamageSmells like cooked fruits or maderized wine.Excessive storage temperatures for prolonged periods or excessive temperature fluctuations
LightstrikeDelicate white wines may take on a wet wool or wet cardboard characteristic.Caused by excessive exposure of white wines to light. Wine bottles should be dark glass and/or stored in dark environments.
Excessive OakOverly oaky and loss of fruit characters.Wine spent too much time on oak.
Acid ImbalanceWine tastes flabby.Too low TA (tartaric acid) and too high pH in wine.
SedimentsWine smells fine but there are visual sediments in the wine.Crystals may be due to tartrate instability; small sediments may be due to unfiltered wine; dark sediments in red wine may be due to unstable color (anthocyanin-tannin bonding).
PlasticWine smells like plastic or kerosene.The use of non-food grade plastic containers in winemaking.

Many of these wine flaws/faults can be avoided altogether by:

  • Start with clean grapes and sanitized winery equipment in appropriate environment.
  • Make sure that you maintain adequate SO2 levels in the wine.
  • Maintain a low pH (higher acidity) which is more resistant to microbial activity.
  • Monitor fermentations (primary, MLF) to completion.

Let’s hope that all your wine tasting experiences will be pleasant without experiencing any of these wine flaws or faults!

– Irene Scott, WSET-3, CSWS
UC Davis Winemaking Certificate 2020
OCWS Wine Education Chair

Wine Education 101: Stay Tuned for More Classes!

Many members have enjoyed our previous in-person OCWS Wine Education classes in 2019 and early 2020. Unfortunately, we had to postpone our remaining 2020 in-person classes due to COVID-19. Since the COVID-19 situation is still uncertain, we are going to continue our classes in the webinar format until the time comes when we can hold these classes in person again. Here are some wine education classes that you can look forward to:

· November 8, 2020 (Sunday @ 3 pm): PAIRING WINES WITH YOUR HOLIDAY MEALS—Learn about the 5 basic food tastes and how they impact the taste of your holiday food.

· December 6, 2020 (Sunday @ 3 pm): CELEBRATING THE HOLIDAYS WITH SPARKLING WINE—Discover different sparkling wines with which you can celebrate the upcoming holidays.

· January 10, 2021 (Sunday @ 3 pm): HOW TO TASTE WINE—Learn how to identify the aromas and flavors in your wine.

· February 7, 2021 (Sunday @ 3 pm): WINES OF SPAIN—Learn about the history of Spanish winemaking, their regions and their wines.

· March 7, 2021 (Sunday @ 3 pm): BORDEAUX – WHAT’S THE BIG DEAL?—Learn what makes Bordeaux wines some of the most sought after in the world.

· April 11, 2021 (Sunday @ 3 pm): JUDGE WINE LIKE A PRO—Learn how wine professionals and judges evaluate a wine for its quality.

· May 2, 2021 (Sunday @ 3 pm): AMERICAN WINE REGIONS AND THEIR WINES—Explore the different wine regions in America, its wines and native grape varietals.

After the 2021 summer wine competitions and OC Fair events are done, we can expect more OCWS Wine Education classes to resume in September 2021. Please note that the above topics and dates are subject to change. Additional details will be announced one month prior to class.

If you have any questions or any class suggestions, please contact me at

– Irene Scott, WSET-3, CSWS
UC Davis Winemaking Certificate 2020
OCWS Wine Education Chair

Wine Education 101: Pour Me Another Glass of Vitis Vinifera

Grapes that are made into wine are often referred to as “Vitis vinifera”.  But are all wine grapes Vitis vinifera?  Can wine be made from grapes that are not Vitis vinifera?  To understand what Vitis vinifera means, we should first understand the basics of Taxonomy, the science involved with the classification of organisms.  We can thank Aristotle for first creating the classification of things as either animal, plant or mineral and further subdivisions based on how they looked or behaved.  However, it was in the 1700s that Swedish scientist Carl Linnaeus developed our current binomial system of Taxonomy.  The Linnaean Classification system has every animal, plant or microbe given a two-part name.  The first part is Genus (broad) and the second part is Species (specific).  Some familiar binomial names you may be familiar with include:  Tyrannosaurus rex, Gorilla gorilla, Saccharomyces cerevisiae, Oenococcus oeni.  Linnaean taxonomic ranks further divided all living things into increasingly more specific divisions such as:  Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

So, with this basic understanding of Taxonomy we know that Vitis is the genus (grapevines), and vinifera is the specific species of this grapevine. Vitis vinifera is a member of the Vitaceae family of woody, climbing vines and is native to the Mediterranean, Central Europe and southwest Asia.

Vitis vinifera is known as the “wine grape” because it is believed to produce some of the best tasting wine.  Most of our well-loved varietal wines belong to this Genus/species:  Chardonnay, Sauvignon Blanc, Viognier, Chenin Blanc, Pinot Noir, Merlot, Cabernet Sauvignon, Barbera, Syrah, Malbec, Grenache, Tempranillo, Sangiovese, Nebbiolo, Mourvedre, Zinfandel, etc.  Our favorite table grape, Thompson Seedless, is also of the Vitis vinifera species and while it doesn’t produce a favorable wine, is great for snacking and dried to raisins.

While the Mediterranean and Europe have their native Vitis vinifera, North America has its own native grape varietals.  The “genus” is the same Vitis, however, the “species” are different from the European vinifera.  Unfortunately, these native American vines often produce a less favorable wine, having an unpleasant “foxy” taste. Because the wines from native American vines are not as pleasant tasting as the European Vitis vinifera, there is less demand and popularity among wine connoisseurs for these varietals.  However, many of these wines are still found in the East Coast or Midwest, where the vines originated from.

The main native American vine species include:

  • Vitis labrusca – produces Concord, Niagara, Cayuga, Catawba and Antoinette varieties.
  • Vitis riparia – a Midwestern variety that produces Bacchus, Baco Noir, Elvira, Frontenac, Marechal Foch, and Triomphe d’Alsace.
  • Vitis rotundifolia – a Southeastern variety that produces the Muscadine grape.
  • Vitis aestivalis – a Midwest favorite that produces the Norton grape – possibly the best tasting wine of the native American varietals.
  • Vitis rupestris – an Eastern variety with high disease resistance and produces Vignoles, Vidal Blanc, Aurore, DeChaunac, Chancellor (French-American hybrids)

While Vitis vinifera wines may taste better than other Vitis species, they also have roots that are susceptible to the root-damaging louse, phylloxera.  In the late 19th century, phylloxera devastated the vineyards in Europe when they were accidentally brought in from imported American grapevines.  These American grapevines had long ago adapted to phylloxera and became resistant to the root-damaging louse.

To overcome the damaging effects of phylloxera, many grape growers experimented with cross-breeding of Vitis vinifera and the phylloxera-resistant American varietals.  These varietals became known as “French-American hybrids”.  While these hybrids were successfully phylloxera-resistant, they didn’t match up to the same high quality taste of the European Vitis vinifera

To solve this problem, grape cultivators found that they could graft the Vitis vinifera vine onto the rootstock of the phylloxera-resistant native American varietals.  This solution produced the same high-quality tasting European Vitis vinifera grapes on phylloxera-resistant native American rootstocks.  To this day, this is still common viticulture practice for Vitis vinifera vines in Europe, America, and other areas where phylloxera is a problem.  In sandy soils where phylloxera is not a problem, you may still find Vitis vinifera grapevines on their own rootstock (some connoisseurs believe this results in better tasting wine).

So, enjoy your glass of Vitis vinifera, while giving thanks to the native American varietals that saved this great-tasting species from extinction!

Irene Scott, WSET-3, CSWS

UC Davis Winemaking Certificate

OCWS Wine Education Chair

Wine Education 101: Wine Trivia and other interesting tidbits!

· Most domesticated grapevines have both male and female reproductive structures and are self-pollinated by wind. [1]

· The first U.S. AVA region was the Augusta AVA in Missouri. This AVA was federally approved on June 20, 1980, eight months before the Napa Valley AVA in California. [2]

· During Prohibition, Alicante Bouschet was the most popular grape varietal for winemaking because of its darker color and its thicker skins allowed for more successful train transportation to the East Coast. [3]

· The Norton grape varietal is thought to be the oldest American grape used for commercial production. This grape varietal also has the highest levels of resveratrol – a beneficial antioxidant. [4]

· The oldest-known winery is the “Areni-1” cave, discovered in Armenia in 2007. This winery is dated to c. 4100 BC and contains evidence of a wine press, fermentation vats, drinking cups and storage jars.  Scientists also discovered evidence of Vitis vinifera seeds and grapevines. [5]

– Irene Scott, WSET-3, CSWS,
UC Davis Winemaking Certificate 2020
OCWS Wine Education Chair


[1] Jackson, R.S., Wine Science: Principles and Applications, Fourth Edition, Academic Press 2014

[2] Missouri Wines: History and AVAs, 2018,

[3] Lukacs, P., American Vintage: The Rise of American Wine, W.W. Norton & Company LTD, 2000

[4] Wine Searcher: Norton Wine, 2015,

[5] Wikipedia: History of Wine,

WINE EDUCATION 101: Summer Wines – Keeping it Light

Summer is finally here!  With summer comes sunshine, warm weather and most likely some poolside/patio wine drinking with friends.  So, what are some good choices for your summer wine drinking that will keep you cool and refreshed?  The key to great summer drinking wines is that they have a lighter body and a higher acidity.  These wines will be refreshing and delicious when served chilled.  Yes, even light-bodied red wines can be delicious when served slightly chilled.

When referring to a wine’s “body” it usually refers to a feel of “weight” in the mouth.  Imagine the different mouthfeel you would experience with water or non-fat milk, then 2% milk, and finally full-fat milk or cream.  This comparison will help you begin to understand what “body” means in wine.  Most varietal wines have a “body” that is typical for that grape varietal.  Wine components that increase a wine’s “body” or “fullness” include sweetness, glycerol, grape and yeast polysaccharides, and phenolic content (in red wine).  On the other hand, the perception of “fullness” can be decreased by acidity.

Acid is one of the main chemical constituents of grapes and gives wine “structure” and the ability to age well.  The main wine acids are the non-volatile organic acids such as tartaric and malic acid which constitute more than 90% of the grape’s acidity.  Malic acid is what you taste when you bite into a crisp apple.  Tartaric acid is that tart taste when you eat grapes (as it is the primary acid in grapes).  While acid can be tasted by taste buds all over your tongue, it is commonly strongest along the sides of the tongue and can often cause increased saliva production.  High acidity or astringency in wines is often balanced with a little sweetness (or perception of) – this is referred to as a “balanced wine”.

With grapes grown in warm or hot climates, the heat will metabolize malic acid such that little is left by harvest – giving wines a lower acidity in warmer climates.  However, cooler climate grapes will often retain more of their malic acid by harvest – giving grapes grown in cooler climates a higher acidity.  In addition, some grape varietals are naturally higher in acidity than other grape varietals. If a wine undergoes “malolactic fermentation”, the stronger malic acid is converted to a softer lactic acid.  Overall, it is the tartaric acid that ends up giving wine most of its taste of acidity.

Based on this understanding of body and acidity, we can choose some nice, refreshing summer wines.  A great guide to grape varietal acidity and body is the “De Long’s Wine Grape Varietal Table” (  This table is a visual reference to various varietals and their body/acidity levels.  We can see on this chart that the Albariño, Aligoté, Colombard, Grüner Veltliner, Pinot Blanc, Torrontés, Riesling, Sauvignon Blanc, Verdelho, Verdicchio, and Vermentino varietals all typically have a lighter body and high acidity.  Any of these would make a cool, refreshing summer white wine.

Want to drink a red wine on a hot day and still be refreshed?  Choose a red wine with a lighter body and higher acidity (avoid wines with heavy tannins), and serve it slightly chilled (about 55oF).  A Pinot Noir is a great example, along with, Barbera, Blaufrankisch, Dornfelder, Freisa, and Sangiovese.

Rosé wine is also an excellent choice for summer with its light body and crisp acidity.  Most Rosé wines have higher acidity as they do not undergo malolactic fermentation where the stronger malic acid is converted to weaker lactic acid.

Sparkling wine is also a great choice for your summer wine – and not just because the bubbles are so fun!  Grapes that are destined for sparkling wines will be picked earlier than other grapes (for still wines).  These grapes will often be picked when the Brix (sugar) level is 18o-21o so that they retain their tartness and acidity that is needed for sparkling wine.

To ensure that you have a wine that has retained a crisp, refreshing acidity, choose a wine from a cooler, fog-drenched region.  Cooler climate wines will retain more of the malic acid that might otherwise become degraded in the heat.  Some excellent cooler-climate wine regions in California include:  Sonoma Coast, Russian River Valley, Monterey, Santa Barbara County and others.

I hope you enjoy a cool, refreshing wine at your next summer poolside party!

Irene Scott, WSET-3, CSWS
Winemaking Certificate, UC Davis
OCWS Wine Education Chair

Wine Education Seminars: Status Update

Our wine education seminars have been such popular events this past year! In early 2020, many of you have enjoyed our seminars on: “Intro to Wine and Wine Tasting” (January) and “Wine, Chocolate and Other Perfect Pairings” (February).

We are disappointed that due to COVID-19 we had to cancel our remaining 2020 seminars on “Wines of Spain,” “Wines of Germany & Austria” and “Wines of North America.”

However, as soon as conditions permit, we will re-schedule these, and more wine education seminars. We may have smaller class sizes and will need to follow guidelines for social distancing, but rest assured, there will be plenty of wine tasting!

Thank you for your patience and understanding. We will notify you as soon as we can safely reschedule these seminars.

– Irene Scott, Wine Education Chair

Wine Education 101: Get to know the Alsace Wine Region

Alsace is not one of the more famous wine regions in France, but is certainly the most unique.  Alsace is one of the most northerly wine regions in France (Champagne is furthest north) and lies in the northeast corner of France along the German border and the Rhine river.  It is a small wine region running north and south, about 75 miles long and averaging about 3 miles wide (not all under vine).

Surprisingly, Alsace, lying so far north, receives some of the lowest rainfall in France.  This is because Alsace lies in the rain-shadow effect of the Vosges Mountains, protecting it from Atlantic influences and keeping it warm and sunny.  This northerly climate along with the warm sunshine, results in ripe grapes with complex aromatics.

Alsace also lies along the Rhine graben, part of a long trough that zigzags across Europe with Alsace on one uplifted side and Baden, Germany on the other uplifted side.   Also unique to Alsace is that it contains 13 different major soil types, the result of ancient years of earth movement and erosion.  Some of the best soils for viticulture are found on the slopes of the Vosges Mountains.

What is most unique about this small wine region is its blend of both French and German cultures.  This amalgamation of cultures is a result of the region being forced back and forth in nationality between Germany and France.  Alsace was a German principality in mid-Renaissance, but was annexed by France at the end of the 17th century.  Alsace was reclaimed by Germany at the end of the Franco-Prussian War.  Alsace was then returned to France at the end of World War I, only to be occupied by Germany during World War II.  At the end of World War II, Alsace was once again returned to France.  The result of these transitions of allegiance was a beautiful blending of cultures, language, cuisine, and especially its wine.

Unlike other French wine regions, Alsace wines are labeled in the Germanic tradition – by grape varietal, rather than the French tradition of place.  Alsace also uses the long, tapered flute bottles as is traditional in Germany.

With its continental climate and 13 different soil types, Alsace land supports a wide diversity of grape varietals.  There are seven primary grapes of Alsace:  Riesling, Pinot Blanc, Gewurztraminer, Pinot Gris, Pinot Noir, Sylvaner, and Muscat.  Secondary grapes include:  Chardonnay (for Crémant production), Chasselas, Auxerrois Blanc, and Klevener de Heiligenstein.

Out of all these grape varietals produced, the four “Noble Grapes of Alsace” are Riesling, Gewurztraminer, Pinot Gris and Muscat.  These are the approved grapes for Alsace Grand Cru AOCs (with Sylvaner approved for one Grand Cru).  90% of wines made in Alsace are white.  While the wines of Alsace are greatly influenced by their German neighbors, they have qualities distinct to Alsace.  When most people think of these four noble grapes, they may think of sweet wines, as often in Germany.  But in Alsace, these wines are traditionally fermented dry and in stainless steel tanks or neutral barrels.  These wonderfully aromatic varietals, in combination with the northerly climate, variety of soils, and abundant sunshine in Alsace, produce wines that have bright acidity, crisp minerality, fresh fruit and floral aromas, full-bodied, with spices and richness unlike other white wines.  You may think that you are already familiar with Riesling, Gewurztraminer, Pinot Gris, and Muscat varietals – but you have not truly experienced the full character of these wines until you have tasted those from Alsace.

Alsace also produces Pinot Blanc (also known as Klevner), having perfumed and smoky notes, and Pinot Noir, which is distinctly lighter and often used in Sparkling Rosés.  You might also come across a Pinot d’ Alsace which is usually a blend of Auxerrois Blanc, Pinot Blanc, Pinot Noir (vinified as white), and Pinot Gris.

Also not to be missed is the Cremant d’ Alsace, the second most popular sparkling wine in France, made in the same méthode traditionnelle as Champagne.  While Alsace lies nearly as far north as Champagne, the climate is warmer and drier so that the grapes reach greater ripeness and have more round, generous flavors. Often made of crisp Pinot Blanc, Cremant d’ Alsace has a creamy texture (from a minimum 9 months sur lie aging) and can have aromas of crisp apples, citrus, honey, yeasty-notes, toasted, buttered brioche and marzipan.

To top this off, Alsace makes incredibly delicious dessert wines.  Late harvest wines made of the four noble grapes, often affected by botrytis (noble rot) are labeled as “Vendanges Tardives”.  These wines are sweet and honeyed, often having a full-body and high alcohol.  Another Alsatian dessert wine is the “Sélections de Grains Nobles”, also a sweet, late harvest wine made of the four noble grapes.  These late harvest wines must be made from botrytis-affected grapes and are hand-picked, berry by berry, through multiple passes in the vineyard.

This small region of Alsace, certainly not the most famous wine region in France, offers up a bounty of wine experiences as full and diverse as their rich culture.  Taste these Alsatian wines and your senses will be delighted by the fresh fruit and floral aromas, accompanied by perfumed richness and exotic spices. With warm weather approaching, these crisp refreshing wines from Alsace should surely be on your summer wine list.

Irene Scott, WSET-3 – Wine Education Chair


Wine Scholar Guild, French Wine Scholar Study Manual, 6th edition, ISBN 978-1-4835-8560-4

Robinsons, Janice.  “Alsace”.

Wine Folly, “Alsace Wine Region: A Manual for Oenophiles”, Sept 12, 2019.

Wine Education 101: Blood, Guts, Bones and Mud in our Wine?

You might think that wine, a product made from grapes, should be “vegan” – not containing any animal products.  This is not necessarily the case for many of our wines today.  In winemaking, there is a process where the wine needs to settle and clarify so that ultimately the bottle of wine that we open is clear of sediment and haze.  Left on its own to occur naturally, this process could take up to a year to settle and produce a clear wine.  Further fining might also need to be performed to remove undesirable constituents such as excessive astringency or bitterness.  In order to accomplish this settling and fining of wines more efficiently, winemakers may use a variety of additives to speed up and enhance this process.  So, could there really be blood, guts, bones and mud in our wine?

The process of “fining” utilizes a substance (often a protein) that is mixed into the wine barrels or tanks.  The substance is attracted to small, suspended particles in the wine that could make the wine cloudy or hazy.  These larger, combined molecules will then precipitate (fall) to the bottom of the wine barrel or tank.  The “fined” wine is then removed from the top.  In theory, there should be little to none of the fining agent left in the “fined” wine. But what fining agents could possibly be left behind in that bright, clear bottle of wine?

In days past, a traditional fining agent used in winemaking was ox blood.  This was added to wine (as a liquid or in dried form) and was a very effective fining agent.  However, in 1997 both the EU and the US banned its use when the mad cow disease scare peaked.  Because of export restrictions of any wine containing blood, there is not much chance that your 25-year old bottle of Bordeaux wine you were saving contains any fining blood.

An effective fining agent used today is isinglass – something you may think of as “fish guts”.  Isinglass is made from the air bladders of fish – usually sturgeons.  It is an excellent fining agent for clarification and removal of bitterness and astringency in white wines.  While the correct use of isinglass can help unmask fruit character, over-use can impart your wine with a “fishy” aroma.

Another non-vegan fining product used in wine is gelatin. Gelatin is a protein made from boiled skin, tendons, ligaments, and/or bones (hooves) with water.  Gelatin is an aggressive protein fining agent that is primarily used to soften red wines by reducing tannins and astringency. Over-use of gelatin fining could result in color loss in red wine and protein instability.

Bentonite is probably the most commonly used fining agent for the clarification and protein stabilization of wine.  However, since it can also remove color, it is more often used in white wine.  Bentonite used in the U.S. is made from clay that is found in Wyoming (sodium bentonite); in Europe, Bentonite is made from clay found in South Africa (calcium bentonite). When Bentonite is dry, it is hard and water-tight; when wet, it is slimy and slick.  Other uses for Bentonite include lubricating oil drill bits; an additive to animal feed (it swells and slows down digestion); used to treat diarrhea; is the mud in “mud baths” and in “mud wrestling”; used in fabric softeners (for ion exchange/water softening).  Bentonite is a very multi-purpose wine fining agent!

A very traditional fining agent for red wine is egg whites, or Albumin (made from chicken egg whites).  This fining agent helps to remove astringency and bitterness and is a good general finishing “polish” for red wines.  Egg whites are not as effective in white wine as it needs the presence of tannins to flocculate.  While the egg whites flocculate with tannins and precipitate to the bottom of the barrel/tank to be later racked off, those with an allergy to eggs might still have reason to be concerned.

Another fining agent that has potential allergy concerns is Casein (potassium caseinate) – the principal protein in milk. Today, Casein is mostly used in its purified form, but skim milk was used in the past and still may be in use today.  Casein is a very gentle fining agent and works well in removing over-oaked aromas, oxidized aromas and browning in white wines.

There are many more products in the winemakers fining “toolkit” today including mineral compounds, polysaccharides (such as chitin found in the covering layer of insects and in the cell walls of fungi), and synthetic polymers (plastics like PVPP).  Most of the products used for fining will precipitate to be bottom of the tank/barrel and be racked off – leaving little or no presence behind in the finished wine.  It is possible that you may find “un-fined” wine – but this can be challenging as even the most traditional Bordeaux wine regions commonly use fining.

Currently, the Alcohol and Tobacco Tax and Trade Bureau (TTB) does not require the disclosure of major allergens on wine labels.  However, there is a current proposal to make labelling of major food allergens on alcohol labels mandatory.  To read more about this, visit:

So, perhaps you may have a greater appreciation (or more disgust) for what it takes to make that finished bottle of wine clear and free of sediments and haze.  Cheers!

Irene Scott, WSET-3 – Wine Education Chair


Wann, Grady, “Fining and Stability”, UC Davis Extension, 2020.

Jackson, R.S., Wine Science: Principles and Applications, Academic Press, 2014

Wine Education 101: Winter Dormancy in the Vineyard

We all love to see beautiful vineyards at harvest – green, full vines with abundant clusters of red or green grapes. Harvest is an exciting time as the vines bring forth their bounty and then take a deep sigh of relief. Following harvest, the vines decorate the landscape with vibrant hues of yellow and orange. But sadly, the vines then give up their leaves to become brown, bare twigs in the ground by winter. But are these vines really as lifeless as they appear? Contrary to their appearance, these vines have prepared themselves to survive and thrive during the cold winter months.

To understand the winter dormancy period, we first need to understand the annual growth cycle of the vine.

Budburst – March-April in Northern Hemisphere (September-October in Southern Hemisphere).

As temperatures begin to exceed 50oF, buds begin to swell and burst open to later become new shoots. Some grape varietals experience bud burst earlier or later than other varietals. Frost at this time can significantly damage these buds and the following early shoots. It is interesting to know that buds will form for the current year’s crop, and also for the following year’s crops (remaining dormant until the following year).


Early Shoot and Leaf Growth – March-April in Northern Hemisphere (September-November in Southern Hemisphere.  Shoots develop and begin a period of rapid growth, spawning budding leaves and tendrils. Until leaves mature and can support photosynthesis, this growth is fueled by carbohydrates that have been stored in the woody vines and roots following harvest. Green leaves begin to fully develop as shoots mature to reach the flowering stage.


Flowering and Fruit Set – May-June in Northern Hemisphere (November-December in Southern Hemisphere)

Depending on temperatures, about 40-80 days after budbreak, flower clusters will begin to appear on the end of the shoots. Most cultivated grape vines are “hermaphroditic” containing both male stamens (pollen) and female ovaries (seeds). With a few weeks of some warm sunshine, flowers grow and lose their protective “cap”, leading to “fertilization” with the next gentle breeze. Unfertilized flowers will fall to the ground, sadly never to become a grape. This stage of the vine lifecycle is critical to development of a healthy crop yield and can be damaged by cold, harsh and rainy weather.

Véraison and Berry Ripening – July-September in Northern Hemisphere (January-March in Southern Hemisphere)

After fruit set, both white and red grapes are hard green berries that are low in sugar and high in acid. These berries continue to grow in size for the next 40-60 days followed by “véraison.” This is the time that berries begin to soften and change color, becoming red, purple, black, or a more translucent, golden green. Warm, sunny weather is needed at this time for the grapes to ripen and accumulate sugars.

Harvest – September-October in Northern Hemisphere (March-April in Southern Hemisphere)

Grapes have reached their peak ripeness: sugars and pH have increased, while acids (such as malic) begin to decline. Tannins and other grape phenolics have matured, giving rise to enticing aromas and flavors. Grape clusters are removed from the vines to begin their journey into becoming wine.

After harvest, leaves remain on the vine where they continue to perform photosynthesis and produce carbohydrate reserves. Eventually, the vines begin to pull back these carbohydrates from the leaves to later be stored, causing the leaves to turn brilliant shades of yellow, orange, and eventually brown. Be aware that red leaves on the vines are not a typical harvest color and often indicate the presence of vine disease.

Now that vines are no longer spending energy producing fruit, their energy can now be spent in their root system. Many new small roots begin to grow and seek out vital nutrients in the soil in a process known as “root flush.”

Winter Dormancy – December-March in Northern Hemisphere (July-September in Southern Hemisphere)

By winter, vines have stored their nutrient and carbohydrate reserves in the cordons, woody trunk and roots. These reserves are critical so that the vines have energy to produce budburst and new shoots in spring – a time when there are not yet leaves on the vine to produce carbohydrates via photosynthesis. Also important is that vines have gone through a dehydration process so that water does not freeze within the vine and root tissues during the cold winter months. Damaging cold winter frosts are not a typical problem in California growing regions – but can be a serious problem in many colder regions.

However, this cold “winter dormancy” is vital to the growth cycle of vines. Temperatures must become cold enough that the above ground vine growth will halt. This cold resting period is necessary to ensure normal budburst and growth cycle in the spring.

Winter dormancy is also the time for winter pruning to be performed. This pruning sets the stage for the next years growing cycle. Woody canes from the previous year’s growth are cut off and new canes are selected from which the new shoots will grow come springtime. This pruning also stimulates the vines so that when warmer weather and sunshine arrive, the vines awaken to a new growth cycle.

So, next time you pass a dormant field full of bare, woody vines, just know that the vines are preparing themselves to greet the spring sunshine with a burst of new growth and start making grapes for your next great bottle of wine.

Irene Scott, WSET-3 – Wine Education Chair


Wine and Spirit Education Trust, 2016. Understanding wines: Explaining style and quality., London, UK.

Urska (2018, Dec. 5). Grapevines During Winter Dormancy,

Burgess, Laura (2016, Jan. 29). Below the Surface: Winter in the Vineyard,

Wine Education 101: Celebrating the Holidays with Sparkling Wine

The holidays are the perfect time of year to celebrate with a glass of bubbling sparkling wine. Those little bubbles in your glass give rise to an explosion of festivities, sparkles, and celebrations – maybe even a few giggles! Sparkling wine is a holiday favorite because it can be found in many different styles, which is what makes it so versatile and easy to enjoy with hors d’oeuvres, dessert, and yes, even with your main course. With so many sparkling styles to choose from, how do you select the best bottle for your celebrations? To start with, we should understand what sparkling wine is and answer the most common questions surrounding it, such as:  1) What is the difference between Sparkling Wine and Champagne?; and 2) Which is dryer, “Extra Dry” or “Brut”?

While all bubbling wine may be considered sparkling wine – not all sparkling wine is Champagne.  If a sparkling wine is labeled as “Champagne” it likely has been made in the region of Champagne, France using the “method champenoise” (also known as “traditional method”).  This method starts with a dry base wine in a bottle, followed by the addition of a solution of sugar and yeast.  This causes a secondary fermentation in the bottle to occur with carbon dioxide bubbles as a by-product.  As the bottle is aging, it is manipulated and angled (a process called “riddling”) such that the “lees” (dead yeast cells) move down into the neck of the bottle. When the aging process is complete (about 1.5 years), the lees are frozen in the neck, and then later expelled by the bottle pressure when the bottle is uncapped.  The Champagne may then be quickly adjusted for sweetness (“dosage”), and blended with small amounts of previous vintages (for consistency) before it receives its final cork.  Most Champagne is non-vintage, unless an exceptional harvest is declared.

Some quality sparkling wines are also made with the above “traditional method”, while less expensive sparkling wines may be made by the Charmat (Tank) method.  This method puts the base wine into a pressurized tank and adds yeast and sugar so that the secondary fermentation takes place in the pressurized tank and is later bottled using a counter pressure filler.

Which sparkling wine is driest?  Here is a guide to the sweetness level of sparkling wine (from Dry to Sweet):

  • Brut Zero or Brut Natural: no sugar (dosage) has been added – typically < 3 g/L residual sugar
  • Extra Brut: < 6 g/L residual sugar
  • Brut: < 12 g/L residual sugar
  • Extra Dry: between 12 to 17 g/L residual sugar
  • Dry (Sec): between 17 to 32 g/L residual sugar
  • Semi-Dry (Demi-Sec): between 32 to 50 g/L residual sugar
  • Sweet (Doux): 50+ g/L residual sugar

Typically, French Champagne is produced using Chardonnay, Pinot Noir, and Pinot Meunier.  You might notice bottles with these labels that indicate which grapes were used:

Blanc de Blanc:  A French term meaning “white from whites” – this is white Champagne made exclusively from the white Chardonnay grape.

Blanc de Noir:  A French term meaning “white from blacks” – this is white Champagne made from black grapes (Pinot Noir, Pinot Meunier).

Cuvee de Prestige A French term meaning “Prestige Cuvee” – this is typically a proprietary blend of premium quality Champagne, usually made from the vintner’s finest grapes in their best vineyard.  These Cuvees are usually designated with a vintage, and carry a premium price-tag.

Here are some other types of sparkling wine that you might find from around the world:

Cremant – this is sparkling wine made in France (outside of Champagne region) using the method champenoise (traditional) method.

Asti (Spumante) – This is a sweet sparkling wine made from the Moscato grape in the Piedmont (NW) region of Italy.

Proseco – This is an aromatic and fruity sparkling wine made from the Glera grape in the Veneto (NE) region of Italy, usually with the cheaper tank method.

Cava – This is sparkling wine made in Spain from a variety of regional grapes with varying levels of sweetness.

Sekt – German sparkling wine has a variety of quality levels with Winzersekt being at the top of the list.  This bubbly is usually made from the Riesling grape using the traditional method.

Now that you have picked out your favorite bubbly, how should you serve it?  Champagne and sparkling wine should always be served cold; its ideal drinking temperature is 45 to 48 °F.

So, let’s raise a glass of our favorite sparkling wine and toast to the coming Holidays and New Year!

Irene Scott, WSET-3

Wine Education Chair