Setting up your winery's lab

Put a wine lab in your winery...

A wine laboratory in the winery should not be optional, but essential.  An in-house wine lab with trained personnel allows for:

• Quick, immediate analytical results.

• Quality control parameters for accurate record keeping prior, during, and after fermentation.

• An emphasis on wine quality to your consumers.

• A savings on shipping costs to external wine labs.

• Better insight into your wines’ quality.

• Avoidance of potential production problems.

Wine is a food product for human consumption, and, therefore, requires quality control operations.  Many winemakers skip analytical procedures with the thought that “he/she knows good wine when he/she tastes it.” Though this might be partially true, it does not account for individual sensory variability.  Analytical results, on-the-other hand provide reliable, consistent numbers directly reflective of wine’s chemistry, and, therefore, quality.  Additionally, analytical results are universal and can be easily transpired from one winemaker to another.

A Primer on Lab Procedures

It has been well-documented that the production of wine involves as much chemistry as it does art.  Although several winemakers may rely on tradition over innovation, following a wine’s chemistry through analytical tests provides a foundation for accurate records, knowledge on a potential wine problem, and the ability to watch chemistry trends in a specific variety (i.e. if a certain variety comes in from harvest with a high pH, high TA year after year).

There are several important topics that are not covered in this report, but vital to understand when discussing wine analysis.  These topics include:

• sampling techniques,

• frequency of sampling,

• proper glassware (e.g. volumetric vs. serological pipets),

• accuracy and precision, and

• molarity vs. normality. 

Such topics can be supplemented with future reports, but a list of references and resources are attached pn oage 8 of this report for your additional reading.
Most traditional wine analysis consists of “wet chemistry” methods, which simply means that analysis is completed in a liquid phase.  pH and titratable acidity (TA) are measurements that evaluate acidity.  pH is a measure of all and any free hydrogen ion concentration in a solution, while TA measures those organic acids that are reactive with a base, typically sodium hydroxide (Zoecklein et al. 1999).  In wine, we commonly express TA in g/L of tartaric acid, as that is the dominant acid in grape juice and wine.  It is often stated that TA is a greater indicator of a wine’s taste, while pH greatly relates to wine’s stability and quality.

In terms of sugar, °Brix are the units we use to describe the grape juice/must sugar content at harvest.  Sugar can be monitored by refractometer or hydrometer during fermentation.  Near the end of fermentation, as you get to about 1 to 2  remaining °Brix  on the hydrometer, I recommend using a Clinitest to more accurately determine residual sugar.  If fermenting to dryness, once a wine is to the 0—0.5% residual sugar mark with the Clinitest, I highly suggest analyzing a sample enzymatically for reducing sugar content (glucose/fructose).  Chemically, reducing sugars are those sugars that contain an aldehyde group and give up electrons, thus reducing other compounds.  The primary reducing sugars in wine are glucose and fructose.  The concentration of reducing sugars is important because they can be easily utilized by yeast and bacteria.  Brett has been shown to utilize 0.1 g/L of residual sugar in wine (Arvik and Henick-Kling, 2002).  However, Zoecklein et al. (1999) notes that a wine can never reach 0% residual sugar due to residual pentoses that are not fermentable by yeast.

The importance of Yeast Assimilable Nitrogen (YAN), which is the total of ammonia + free amino nitrogen (FAN) is also well documented.  The YAN value becomes most important during fermentation with too little or too much nitrogen often the cause of hydrogen sulfide (rotten egg) aroma and flavor.  Hydrogen sulfide can cause mercaptan formation during wine aging, which is more difficult to treat.

Reducing sugars, YAN (ammonia + FAN), and malic acid concentration can all be tested by enzymatic techniques, which can be purchased as kits.  These kits contains reagents and enzymes that cause a chemical reaction to occur in the juice or wine, specific to each analyte.  A “before” and “after” sample is measured by an absorbance reading using a spectrophotometer.  A spectrophotometer is an instrument that measures the amount of light that passes through a sample.  

Lab Analysis Set Ups

Always remember to check what protocols you want to use in your lab prior to buying equipment.  The following is a generalized list of materials you will probably need to get started.

pH

• pH meter with electrode & Automatic Temperature Compensation (ATC) probe - Potential suppliers:
  

•  Enartis Vinquiry

•  Fisher Scientific

• VWR

• Sigma-Aldrich

• Electrode storage holder & solution (or pH 4.00 buffer)

• 50 mL glass beakers

• pH buffers (3.00, 4.00, 7.00, 10.00)

• Distilled water

• Optional: stir plate (with or without hot plate) and stir bars

Titratable Acidity (TA)

• 25 or 50 mL buret - Potential Suppliers:
  

• Presque Isle Wine Cellars

• Enartis Vinquiry

• Scott Labs

• Buret stand

• Buret clamps

• Stir plate (with or without hot plate)

• Stir bars

• 250 mL glass beakers

• 5 mL volumetric pipet

• Degassing source/sparge stone (for wine samples)

• Normalized Sodium Hydroxide (NaOH)

• Normalized Hydrochloric Acid (HCl) for TA Calibration

• Phenolphthalein or pH meter (for endpoint identification)

• Distilled water

Brix for Juice Analysis

• Refractometer - Potential Suppliers:
  

• Presque Isle Wine Cellars

• Enartis Vinquiry

• Distilled water

• Kim Wipes

• Disposable Pipets

Yeast Assimilable Nitrogen (YAN)

Ammonia by Ion-Specific Electrode

• Ion-specific electrode (with pH meter; must have millivolt reading capability)

• 250 mL glass beakers

• Stir plate (with or without hot plate)

• Stir bars

• 1L volumetric flask

• Ammonium Chloride (NH4Cl)

• De-ionized water

• 1N Hydrochloric Acid (HCl)

• 10M Sodium Hydroxide (NaOH)

• Ammonia standards (bought or prepared from Ammonia Stock Solution)

Ammonia by Enzymatic

• Spectrophotometer (Abs. at 340 nm) - Potential Suppliers:
  

• Enartis Vinquiry

• Fisher Scientific

• Sigma-Aldrich

• Ammonia Enzymatic Kit - Potential Suppliers:
  

• Enartis Vinquiry (Vintessential Kit)

• Megazyme

• Cuvettes

• Cuvette Rack

• Parafilm

• Eppendorf Pipettors (10-100 μL; 20-200 μL; 100-1000 μL)

• Eppendorf Pipet Tips

• Stop clock

Free Amino Concentration

• Spectrophotometer (Abs. at 335 nm or 340 nm)

• Free Amino Acid Nitrogen Enzymatic Kits - Potential Suppliers:
  

• Enartis Vinquiry (Vintessential Kit)

• Megazyme

• Vortex Mixer

• Centrifuge & centrifuge tubes OR Whatman filters (to remove gross solids)

• Cuvettes

• Cuvette rack

• Parafilm

• Eppendorf pipettors (*see above*)

• Eppendorf pipet tips

• Small (~100 mL) volumetric flasks (for isoleucine standards, depending on kit)

• Stop clock

• Distilled water

Malic Acid Concentration

• Spectrophotometer with UV capability (Abs. at 340 nm)

• Cuvettes

• Cuvette rack

• Eppendorf pipettor (*see YAN*)

• Eppendorf pipet tips

• Malic Acid Reagent Kit - Potential Suppliers:

• Roche Custom Biotech
  

• Enartis Vinquiry (Vintessential Kit)

Microbiology - Microscope

• Phase Contrast Microscope - Potential Suppliers:
  

• Enartis Vinquiry

• Microscope slides

• Cover slips

• Lens paper

• Pasteur pipets

• Immersion oil

• Methylene Blue (Yeast stain)

Alcohol Concentration

• Ebulliometer - Potential Suppliers:
  

• Presque Isle Wine Cellars

• Enartis Vinquiry

• Dujardin-Salleron

• Thermometer (86-102°C)

• Dial alcohol scale

• Alcohol lamp (fueled with >90% ethanol)

• Distilled water

Volatile Acidity

• Cash still assembly

• TA assembly (with 2 burettes—50 mL)

• 250 mL Erlenmeyer flasks

• 10 mL volumetric pipet

• 5 mL serological pipet

• Pipettor

• 0.1N Sodium Hydroxide (NaOH)

• Phenolphthalein

• 1+3 Sulfuric Acid

• 0.02N Iodine

• Starch Indicator

Free and Total SO2 (Sulfur Dioxide)

Aeration Oxidation Set Up (Free SO2)

• AO Assembly

• Metal stand

• Impinger set

• 100 mL side port flask

• Support ring for flask

• Bubbler/stopper (into side of side port flask)

• Stopper/glass tubing adaptor (into top of side port flask)

• 3-fingered clamps (2 to 3 per set up)

• Clamp holders

• Tygon tubing

• Vacuum: airejector aspirator

• Quick disconnect plastic connector

• Amber latex tubing

• Flowmeter (0.4-40 mL/min)

• 20 mL volumetric pipet

• 10 mL serological pipet

• Pipettor

• TA assembly

• 3-30% Hydrogen Peroxide (diluted to 0.3%)

• 25% Phosphoric Acid

• 0.01N Sodium Hydroxide (NaOH)

• SO2 Indicator

Ripper Set Up (Total SO2)

• 250 mL Erlenmeyer flasks

• 25 mL serological pipet

• 10 mL serological pipet

• 5 mL re-pipettor (for Sulfuric Acid)

• Pipettor

• TA assembly

• 0.02N Iodine

• Starch Indicator

• 1+3 Sulfuric Acid

• 1N Sodium Hydroxide (NaOH)

Extra Reading, Resources, & Protocols

“Brettanomyces bruxellensis occurrence, growth, and effect on wine flavor” by Torey Arvik and Thomas Henick-Kling in Practial Winery & Vineyard Journal, May/June 2002.