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Friday, November 15, 2019

Taste & Aroma Profiles, Part 4


                                    Almond-like flavor is a classic profile of Champagne

This is the final in a four part series on the aromas and flavors of wines produced by chemical reactions during the fermentation process.  In review, we’ve discussed the buttery profile caused by the conversion of harsh malic acid to the softer lactic acid.  Next, the science behind a variety of fruit flavors in wine was detailed, followed by a discussion of the chemistry behind grassy aromas and smells.   This final blog will address another flavor component caused by a chemical reaction during wine-making.  It will also discuss other common flavors present in wine that have nothing to do with the fermentation process, but everything to do with the oak barrel.


Almond nuances are classically associated with sparkling wine.  This almond profile is caused by the release of a chemical component produced by yeasts during fermentation.  Sparkling wines that have rested “on their lees” (i.e. had contact with the dead yeast cells) often have almond aromas and flavors due to the chemical compound benzaldehyde.  This chemical actually has an almond aroma.  Wines that undergo batonnage (frequent stirring and mixing of the lees) also exhibit almond tones.

A final note of clarification:  not all aromas and flavors in wine, however, are related to chemicals produced during fermentation.  Oak barrels can play a huge part in influencing both a wine’s smell and taste.  The following are examples of chemicals in oak that can alter the taste and smell of wine:
  • Eugenol:  responsible for spices such as clove, nutmeg & cinnamon (note that this chemical is actually found in all of these spices)
    Vanillan:  the compound, also found in the vanilla bean, gives off vanilla aromas & flavors
  • Furfural:  imparts dried fruit flavors & coffee nuances (furfural is also found in coffee)
In summary, there are hundreds of chemicals found in wine.  Some occur because of chemical reactions in fermentation; others are present due to other factors (such as the use of oak).   What is interesting to note, however, is that most of these chemicals do not reach the threshold of one being able to distinguish them.  The majority of people have an average threshold for tastes and smells.   However, there are some people, who have a more sensitive threshold and may be able to distinguish tastes and smells more readily than others.






Friday, November 8, 2019

The Science Behind Grass in Your Glass


                     New Zealand's Greywache Sauv Blanc is one of the country's benchmarks
                                
This is the third in a four-part blog series on aromas and flavors in wine that are directly related to chemicals produced during the wine-making process.  Today, we’ll discuss the grassy smell and taste found in wine.  These isn't a figment of your imagination, but is a scientific fact that occurs as a direct result of chemical changes during fermentation.

Have you ever wondered why your Sauvignon Blanc (SB) is reminiscent of freshly mowed grass?  This classical grassiness taste and nose found in many SB’s is due to chemicals called aldehydes.  These compounds, released during fermentation as yeasts turn SB grape sugar into alcohol, evoke the smell of just-cut grass.  The SB grape has  the ability to produce high level of aldehydes.  The perception of grassiness is driven for the simple reason that these same chemicals are also found in grass.  Cutting grass releases these highly fragrant chemicals into the air.

The less ripe the SB grape, the higher the propensity is for aldehydes, and thus the stronger the grassy profile.  New Zealand SB’s are known for their traditional grassy notes.  Kiwi SB’s are purposely picked a little less mature for this reason, but also responsible is the moderate climate where this country’s SB grapes are grown.  The Loire Valley also is famous for SB.  As this area is fairly far north, SB often can’t ripen to its fullest degree, so Lorie wines classically also have grassy nuances.   In contrast, California SB has abundant sun and generally is picked more mature.  This translates to less intense grassy nuances.  In Cali’s warmer growing areas, SB’s actually can take on ripe tropical notes.

Next week we’ll finish this series by discussing one of the common flavors in sparkling wine which is also caused by the science during fermentation.


Friday, November 1, 2019

How Can Wine Smell like a Banana?


                 Banana, green apple & gooseberry profiles are the result of chemical reactions

Why in the world does a wine taste or smell like any fruit other than a grape?  This is the second article in a blog series on the science behind certain flavors and aromas in wine.  This particular article will discuss three fruit flavors/fragrances that can appear in wine.  In fermentation, yeasts eat the sugar in the grapes and convert it to alcohol.  In this process thousands of various chemical compounds are produced.  All three fruit flavors below are a result of these complex chemical processes.

Banana
The banana-like smell and taste is a result of a chemical compound by the name of isoamyl acetate, a by-product of yeasts during fermentation.  The isoamyl acetate also occurs naturally in the banana plant, as well as in pears.  It is present in most wines, however, it is below the threshold of one’s ability to taste it.  It should come as no surprise that artificial banana flavoring is made from isoamyl acetate.

This banana smell and taste can appear in both white and red wines.  Aromatic white wines that are fermented at cooler temperatures (lower temperature enhances the amounts of isoamyl acetate) often display ripe banana notes.  For example, that banana nuances can often be found in Chardonnay, Pinot Gris and Albarino.  Beaujolais is one of the few red wines that has a banana profile.


Green Apple
This flavor and smell profile found in wines is due to the lactic acid which is created during malo-lactic fermentation.  Lactic acid gives off green apple-like scents and flavors, in addition to a creamy mouth feel.  Wines that have pronounced green apple character are classically cool climate dry whites such as Chardonnay, Riesling and Gruner Veltliner.


Gooseberry
Like green apples and banana nuances, this flavor and aroma is not part of the grape.  Gooseberry is created during alcoholic fermentation and is a by-product of yeast activity.   This fruit is typically less sweet so its taste is on the tart side (think pucker),  but gooseberries can also have a slightly floral scent.  Generally found in aromatic whites, gooseberry is classically associated with Sauvignon Blanc (particularly those from cool weather regions such as coastal New Zealand, or France’s Loire Valley).

Keep in mind that each person has a different innate level of tasting various substances.  It doesn’t matter what you taste or don’t taste in a wine.  The only thing that counts is if it pleases you.