The Essential Guide to Measuring SO2 in Wine

The Hanna Instruments team doesn't just want to sell you great instrumentation; we want to work with you to make your product the best it can be. That's why we're constantly creating resources for our customers in all industries.

Our Measuring SO₂ in Wine eBook is designed as a resource for winemakers who need to put an effective SO₂ testing program in place. It covers how SO₂ affects wine quality, the necessary tools needed to measure SO₂ levels, and how to use these tools to get accurate results.

Here is a brief recap of the three sections included in the eBook.

Chapter 1: Why SO₂ Matters

This section covers the very significant and specific benefits to adding sulfur dioxide to wine.

• Helping to reduce undesirable bacteria, molds, and yeasts.
• Acting as an antioxidant (slowing down the oxidation process).
• Maintaining wine's desirable characteristics such as taste, fruit flavoring, and aroma

Chapter 2: What You Need

The second section outlines the equipment needed for an accurate and fast SO₂ analysis. We focus on the use of automatic titrators using the popular modified Ripper Method.

Here's what you need:

Automatic Titrator

Must have:

• An automatic titrator with the Ripper Method of SO₂ analysis built-in to test both free and total SO₂.

Good to have:

• A precision-dosing pump to determined the volume of titrant used to reduce effort and improve accuracy.
• On-screen features such as real-time graphing so you can follow the titration progress on the screen.

Electrode

Must have:

• An ORP electrode to monitor the redox reaction.

Good to have:

• The ORP electrode should have a clogging prevention system (CPS) technology to prevent the reference junction from getting clogged.

Solutions

• Titrants: Standardized titrant is crucial to ensure accurate determination of SO₂
• Titration Reagents: All chemicals used for titration should be reagent-grade. These include 25% sulfuric acid, potassium iodide, and stabilized iodine (iodate).
• Cleaning Solutions: Clogged reference junctions are the number one reason for poor performance in SO₂ measurement. This is particularly apparent in wine because wine samples (must, juice, etc.) leave residues on the junction of the ORP electrode. A dirty or clogged junction will result in a noisy, slow responses and/or excessive drift. Cleaning solutions ensure that the electrode is free from wine deposits.
• Storage Solutions: A dry ORP electrode will slow the response time. A few drops of a storage solution should be added to the protective cap prior to storage.

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Chapter 3: How to Measure SO₂ in Wine

The section gives you a step-by-step process on calibrating and measuring SO₂ during wine making. You will also get the steps needed to properly maintain and store your electrode – a task that's critical for accurate measurement.

Tips in this section include:

Priming the pump

The pump cycle should be performed:

• If there is no titrant in the tip.
• Whenever the dosing system tubes are replaced.
• Whenever a new bottle of titrant is used.
• Before starting a pump calibration (if applicable).
• Before starting a series of titrations.

Electrode Maintenance 

• If titrations are slow, the electrode many need to be cleaned or the electrolyte may need to be changed

There is even a printable checklist that you can keep in your lab to make sure you never skip a step!

Click the eBook to download it now!