Wine Quality Sensor

Question

I am an engineer who's built a wine quality detector. My sensor can pick up a wide variety of chemicals at levels as low as parts per million (ppm).

With no background in wine production myself, I have a few questions regarding how winemakers perform quality control at their facilities.

These questions are:

1. Do commercial winemakers care about uniformity and consistency in their wine?

2. After grapes are harvested, what methods can winemakers employ to alter the taste of their wine? For example, if a the grapes from a particular harvest is too sweet, is there anything the winemaker can do to change this?

3. I understand that there are inherent variations associated with harvests from different years (hence the year of the wine actually matters). Do winemakers strive to achieve a certain level of consistency across different years?

4. Besides ethanol, do winemakers quantify other chemicals present in wine? The list of chemicals that we can detect are:

Sugar: Glucose, Sucrose and Fructose

Acid: Acetic Acid, Citric, Isocitric, Lactic, Tartaric and Malic

Impurities: Volatile Phenols, Geosmin, Haloanisoles, Methoxypyranzines

Others: Catechin, Epicatechin, Gallocatechin gallate, Myricetin, Resveratrol, Quercetin, Syringic acid, Hydroxybenzaldehyde, p-Vanillin

Are there other chemicals that you would like to test?

Answer 1

My understanding is that commercial winemakers make extensive use of blending post-fermentation to create a consistent product. They will blend wines makes in the same year, as well as blending wines made in different years. The solera, used primarily in sherry production, is an expression of this process.

Another chemical in the must that is important to quantify is free sulfur. Grape juice contains small amounts of sulfur, which the wine maker will supplement at various points before and during fermentation.

Answer 2

Some commercial wine producers do care about consistency and go to great lengths to ensure a consistent product. Others believe more in the variability and craft aspects of their product with a great year making a great wine and every year being different.

Wine makers can add extra water to their wines or mix in a too dry batch; not allowed in France for VDP/Appellation wines where traditional strict methods must be followed.

Likewise if a harvest is too low in sugar modern wine producers with vacuum distill water of the liquid to get the correct starting concentrations of sugars.

There are a large number of other chemicals that are the fermentation by products of yeast that are important in both wine and beer flavour profiles. Stressing yeasts tend to produce alter production of these by products sometimes taking them over flavour thresholds. It is when this occurs that producers will care. So long as it is below the perception threshold for aroma or flavour then chances are it will not be important.

Answer 3

It really depends on the producer and the wine product. Some wine producers try to create a consistent product, while others try to make the best wine they can with the crop they've been given.

Producers who make "consistent wine" tend to hold wine for many years and blend it together gradually over time so that what comes out of the process is as close to last year's as possible.

Wine makers who try to make the best that this year can give them alter their wines very little little.

Note that boujalais nouveau is almost never the same year to year.

I think your idea is a good one that will resonate with winemakers who want to manage their wines at the chemical level, I think that would be most producers, but not the highest end producers who value the traditions.

Also keep in mind you are most likely to run into home vintners here rather than producers.

Answer 4

If a wine is too sweet, then fermentation is not complete. Unfermentable sugars are not usually present in wine unless they have been added.

Can you detect microbial levels? Dissolved CO2?