The purpose of this document is to explain critical steps in quality wine production that requires analytical procedures that Westco/Alliance products can help with.

In an effort to be thorough and clear, we will show analytical procedures used for each step in wine production.

I - Harvest

To determine the date to start the harvest we need to know the quantity of sugar, the total acidity, and pH in the grape juice.

Normal values are:

• Total sugars : 200 g/L ( glucose + fructose ). Although a handheld refractometer can be used in the field, more accurate results can be obtained in the laboratory using the Infrascan.
• Total acidity : 5 to 15 g/L ( Acetic acid ), depending on the type of grape and maturity. The Westco SmartChem analyzer system is used to not only analyze for Total Acidity, but also give specific results for succinic acid, lactic acid, tartaric acid as well as volatile acids.
• pH : around 3 to 4. The Westco SmartChem system gives you fast accurate results for pH.

II - Fermentation

A. Dry red or White wine

To obtain dry wine we have to transform all the sugars (glucose, fructose, or additional sucrose ) into alcohol. Around 16 to 17 g/L of sugars produces 1 % vol of alcohol, depending of the type and quality of the yeast used. The fermentation is finished when the amount of the residual sugar is below 2 g/L as glucose. The Westco/Alliance Infrascan system helps you monitor the sugar content for glucose and sucrose while the Westco/Alliance SmartChem monitors the fructose content.

During this step it is necessary to avoid any transformation of the alcohol into acetic acid mainly as a result of poor quality yeast, It necessary to measure the amount of Volatile acidity to control acetic acid formation . The acceptable range for wine is 0 to 1 g/L as Acetic acid. If the value is over 1 g/L the wine is not good to drink . The SmartChem system accurately and quickly measures Volatile acidity.

To stop this bad transformation it is sometimes necessary to add SO₂ in the fermenting must to stop the proliferation of bad bacteria. Only free SO₂ is available to protect the must or the wine, but it is forbidden to add too much SO₂ in the wine (below 150 mg/l for a red wine in France). The SmartChem is used to monitor free and total SO₂.

The basic parameters to control during this step are:

• Reducing sugars : below 2g/L ( glucose ) - Infrascan
• Volatile Acidity : 0 to 1 g/L ( Acetic acid ) - SmartChem
• Free SO₂ : 0 to 50 mg/l ( S02 ) - SmartChem
• Total SO₂ ( free + combined ) : 0 to 150 or 200 mg/l ( SO₂ ) - SmartChem
• Alcohol : 10 to 14 % Vol ( alcohol ) - Infrascan

Another fermentation takes place after the first one, the malo-lactic fermentation. The malic acid of the must or the wine is transformed into lactic acid. This fermentation has to be finished normally before bottling the wine to avoid fermentation by products inside the bottle.

To control that it is necessary to analyse:

• Malic acid : 0 to 5 g/l - Infrascan
• Lactic acid : 0 to 5 g/l - SmartChem

B. Sweet or semi-sweet wine

To produce this type of wine it is necessary to stop the fermentation at the required level of sugar or to add external sugar (sucrose or sugar from grapes) to dry wine. To stop the fermentation it is necessary to add alcohol and/or SO₂. The malo-lactic fermentation has to be done before bottling and malic and lactic acids must be controlled.

The basic parameters are:

• Reducing sugars ( glucose + fructose ) - Infrascan
• Glucose 10 to 100 g/L ( glucose ) - Infrascan
• Volatile acidity : 0 to 1 g/L ( Acetic acid ) - SmartChem
• Free SO2 : 0 to 50 mg/l ( SO2 ) - SmartChem
• Total SO2 : 0 to 400 mg/l ( SO2 ) - SmartChem
• Alcohol : 10 to 14 % Vol ( alcohol ) - Infrascan
• Malic acid : 0 to 5 g/l - Infrascan
• Lactic acid : 0 to 5 g/l - SmartChem

C. Sparkling wine

To produce sparkling wine such as Champagne it is necessary to develop a third fermentation of sugars into alcohol inside the bottle.

The dry wine is put inside the bottle with an additional amount of sugar and fresh yeast to produce alcohol and CO₂ inside the bottle after fermentation. The pressure inside the bottle can reach up to 5 bars.

Before selling this type of wine, the yeast is removed and some sugars added according the taste of the customer.

The dry wine is controlled as above, additionally, Total sugars are measured in the sparkling wine: 0 to 50 g/L (glucose) - Infrascan.

D. Other analyses

During the fermentation step some other parameters are required, depending on the production technique, the wine, and the quality.

• Iron : 0 to 20 mg/L - SmartChem
• Copper : 0 to 5 mg/L - SmartChem
• Tartaric acid : 0 to 5 g/L - SmartChem
• Follin index ( to evaluate the level of polyphenols )
• OD ( Optical Density ) at 420 nm, 520 nm, 620 nm - SmartChem

III - Wine Aging

The main trouble to detect during the wine aging process is the bad transformation of alcohol into acetic acid. It can appear in bad aging conditions: the container not completely full and/or wine in contact with air.

The oenologist should follow the evolution of the Volatile acidity, the Free SO₂ and the Total SO₂ to be able to adjust the SO₂ in case of increasing level of the Volatile acidity by addition of SO₂.

• Volatile acidity - SmartChem
• Free SO₂ - SmartChem
• Total SO₂ - SmartChem

IV - Bottling

The producer must make sure that the amounts marked on the label are corresponding with the wine inside the bottle.

The main parameters are:

• Alcohol - Infrascan
• Volatile Acidity - SmartChem
• Total Acidity - SmartChem
• pH - SmartChem
• Total SO₂ - SmartChem
• Reducing Sugars - Infrascan

We realize that this is a gross over simplification of the art and craftsmanship that goes in to producing fine wines, however, we hope that this will serve as an over view as to how Westco Scientific Instruments can help you.

Westco/Alliance is your partner in success for the production of superior wine.