Our Sentia™ wine analyzer has a rich color touch screen display with step by step instructions to guide the user. Select your a flag below to download the user guide in your language. If you need more help, refer to the hardcopy user guide that came with your analyzer or download an e-copy below.
Your wine, time and effort is precious – don’t risk spoilage by cutting corners in free SO₂ monitoring. A tailored barrel management program should incorporate regular testing of each barrel, to eliminate the financial risk of compromised wine.
The Importance of Free Sulfur and its Frequent Measurement
Wine production is a delicate balance of art and science, with each step meticulously managed to ensure the final product’s quality and longevity. Among the critical components in winemaking is the use of sulfur dioxide (SO₂). This compound plays a vital role in safeguarding wine against microbial spoilage and oxidative damage, making it an indispensable tool for winemakers (Waterhouse et al., 2016).
Why is sulfur dioxide added to wine?
Sulfur dioxide is added to wine primarily to protect it from undesirable microbial growth and the detrimental effects of oxygen exposure. Without this protective agent, wines can suffer from a range of microbial and oxidative spoilage issues:
Anti-yeast: SO₂ inhibits harmful yeasts such as Dekkera bruxellensis, which can produce off-putting aromas reminiscent of horse sweat and medicinal odors (Grainger & Tattersall, 2016), and Saccharomyces cerevisiae, which can cause spoilage through unwanted refermentation.
Anti-bacteria: SO₂ prevents spoilage from bacteria, such as lactic acid bacteria which can cause taints like mannitol, mousiness, geranium odors, and diacetyl, and acetic acid bacteria which can produce vinegar-like and nail polish remover aromas (Bartowsky, 2009).
Enzymatic Oxidation: SO₂ decreases catechol oxidase activity, an enzyme that can lead to oxidative spoilage (Waterhouse et al., 2016).
Non-Enzymatic Oxidation: SO₂ scavenges hydrogen peroxide, preventing the conversion of ethanol to acetaldehyde (sherry-like, bruised apple aroma) and acetic acid (vinegar aroma and taste). It also binds acetaldehyde to prevent phenolic polymerization, which leads to premature aging, increased bitterness and astringency, and red pigment precipitation (Waterhouse et al., 2016).
Why do we measure free sulfur dioxide?
Testing for sulfur dioxide is crucial because its protective level decreases over time due to various reactions (Waterhouse et al., 2016). Regular barrel-by-barrel monitoring helps to:
Identify if sulfur additions are missing or excessive.
Detect early signs of sulfur depletion from microorganisms and oxidative spoilage and prevent their further effects.
Ensure barrels, which are more prone to contamination due to their high surface area and permeability, remain protected.
Maintain wine quality and longevity.
Maximize product value, revenue, and market suitability.
Control risks and prevent costly mistakes, such as the need to downgrade premium products.
How often should we conduct free sulfur measurements?
Each barrel, despite containing the same wine, undergoes unique variations in oxygen exposure, microbiomes, oak characteristics, and temperature (Zamora, 2019). These factors create distinct aging trajectories, requiring an individualized approach to monitoring and maintenance.
Frequent individual barrel analysis is crucial for reducing risks. This precision approach safeguards your assets and prevents quality downgrades.
Why do we measure free sulfur dioxide?
Testing for sulfur dioxide is crucial because its protective level decreases over time due to various reactions (Waterhouse et al., 2016). Regular barrel-by-barrel monitoring helps to:
Identify if sulfur additions are missing or excessive.
Detect early signs of sulfur depletion from microorganisms and oxidative spoilage and prevent their further effects.
Ensure barrels, which are more prone to contamination due to their high surface area and permeability, remain protected.
Maintain wine quality and longevity.
Maximize product value, revenue, and market suitability.
Control risks and prevent costly mistakes, such as the need to downgrade premium products.
How often should we conduct free sulfur measurements?
Each barrel, despite containing the same wine, undergoes unique variations in oxygen exposure, microbiomes, oak characteristics, and temperature (Zamora, 2019). These factors create distinct aging trajectories, requiring an individualized approach to monitoring and maintenance.
Frequent individual barrel analysis is crucial for reducing risks. This precision approach safeguards your assets and prevents quality downgrades.
Avoiding composite sampling pitfalls:
While composite sampling from a selection of barrels might seem efficient, it assumes all barrels have similar free sulfur concentrations. Sampling only a small subset can lead to incorrect assumptions, affecting the winemaker’s decision process and barrel management. To identify outliers and reduce variance and financial risk, transition to a higher percentage of barrel-by-barrel sampling and customized additions. This ensures accurate protection levels in more barrels, improved decision-making and early problem detection.
Figure 2: Composite sampling can lead to inaccurate decisions to sulfur or not sulfur barrels.
Tailored barrel sulfur management:
Tailored barrel sulfur management involves precise and frequent monitoring to adjust sulfur levels as needed, ensuring that each barrel reaches its critical sulfur point. This proactive approach is essential for maintaining the delicate balance required for premium wines and achieving consistent quality across all barrels.
Monthly and Bi-Weekly Testing
Regular sulfur dioxide testing is fundamental to this tailored management approach:
Monthly testing: By testing each barrel once a month, winemakers can make necessary sulfur adjustments to maintain optimal levels and prevent quality degradation.
Bi-weekly testing: During critical periods such as post-fermentation, pre-bottling, or times of increased spoilage risk, bi-weekly testing and adjustments become vital. This increased frequency helps address rapid changes and potential issues more effectively.
Special Considerations for High-Tier Wines
High-tier, premium wines should demand even more rigorous sulfur management. More frequent measurements ensure these premium products maintain their superior quality and meet market expectations.
Additional Testing Situations
Beyond the regular schedule, certain situations necessitate immediate sulfur dioxide testing:
Bottling and blending: Testing before these processes ensures that the sulfur levels are adequate to protect the wine during these critical transitions.
Visual, aromatic or abnormal cues: The presence of unexpected gas bubbles, sulfur smells, or vinegar-like aromas signals the need for immediate testing and potential adjustment of sulfur levels.
Don’t be caught out – regular and precise monitoring of sulfur dioxide levels in each barrel ensures the longevity and quality of your wine, maximizing product quality and market value while minimizing potential downgrades and financial risk.
Are you sending samples to a lab for testing? See how much time and money you could save by testing free sulfur with Sentia. Check out the new Sentia Free Sulfur Analysis Cost & Time Saving Calculatorhere.
Bartowsky, E. (2009). Bacterial spoilage of wine and approaches to minimize it. Letters in Applied Microbiology, 48(2), 149–156. https://doi.org/10.1111/j.1472-765X.2008.02505.x Grainger, K., & Tattersall, H. (2016). Wine Production and Quality (2nd Ed.). John Wiley & Sons Inc. Waterhouse, A., Sacks, G., & Jeffry, D. (2016). Understanding Wine Chemistry.John Wiley & Sons Inc. Zamora, F. (2019). Barrel Aging; Types of Wood. In Red Wine Technology, pp. 125-147., Edited by Antonio, M. Academic Press.
When turning on the Sentia Device for the first time, a connection to strong Wi-Fi signal is required, preferably 2.4 gHz (Wi-Fi frequency band). You can also use your phone hotspot.
During registration, you will also be prompted to enter your email to receive a verification code, which may go to your junk mail.
After setup, update your device to the latest software version. Learn how to update the Sentia software here.
Operating and Storage Conditions: Operate the device within 10-30°C (50 -86°F) and <80% humidity (without condensation). Store the device at 2-40°C (35.6-104°F) and <80% humidity (without condensation).
Connect to Wi-Fi: When conducting a test, you do not require Wi-Fi connection, however whenever in range, we recommend staying connected to export test results and receive software and calibration updates.
Charging and battery care: Use the supplied charging cord. Avoid using generic chargers. Maintain good battery charging habits and do not overcharge. Find battery care and maintenance tips here.
Cleaning: Clean spills immediately. Follow general and strip port cleaning instructions here. Use the Sentia analyzer case to further protect the device from spills.
General Use of Strips and Buffer
Close Vial Lids: Close vial lids after removing strips and pipetting buffers.
Do Not Mix Buffers: Avoid mixing buffers from different vials, even if the batch number is the same.
Storage: Store strips and buffers as recommended on the vial.
Use Strips Quickly: Use strips within 10 minutes of removing from the vial.
Single Use: Do not insert the strip into the device more than once.
Dry Hands: Handle strips with dry hands.
Avoid Flooding: Do not flood the test strip with the sample.
No Additional Sample: Do not add more sample once analysis has started.
Sample handling and dilution
Retrieve Your Wine Sample: Ensure the sample accurately represents the wine being measured and is consistently removed from the same homogenate area of the tank or barrel.
From a Sample Tap: Let some wine flow out first before collecting your sample.
From a Barrel: To obtain a representative sample use a wine thief to draw the sample from well below the surface.
Immediate Testing: Test the sample immediately after retrieval to prevent changes in the analyte concentration.
Sample Pre-treatment: Degas samples with visible gas, except when testing for free SO2.
For turbid samples or those with excessive particulates, centrifuge, filter, or let settle before analysis, except when testing for free SO2. See the Sentia Guide to Sample Preparation here
Equilibrium: Allow the wine to stabilize after any additions or significant changes. For example, after adding sulfur, allow the wine to stabilize for at least 12 hours, before conducting free SO2 analysis.
Minimize Oxygen Exposure for Free SO2 testing: When transferring the sample, be careful not to draw air up through the transfer pipette to prevent oxygen from bubbling through the sample.
Ensure the pipette or wine thief is filled with sample to minimize the surface area of wine exposed to oxygen. Apply the sample immediately after drawing. If immediate analysis is not possible, fill a vial to the top with sample and cap tightly with no air pocket.
For further information regarding how to ensure accurate free sulfur results, see here.
Comparison testing If conducting a comparison analysis, use the same aliquot for both Sentia and the reference method. Minimize the time interval between the Sentia test and the reference method test. For free sulfur, always test the sample on Sentia first due to the small sample size and associated risk of oxidation.
Using a Micropipette:
Ensure accuracy: Follow the manufacturer’s instructions for use, maintenance, and service. Practice with water first to get comfortable with the pipette.
Select the right pipette: Use the appropriate pipette for your task. For example, for Sentia, use a 100 – 1000 uL micropipette.
Use correct pipette tips: Always use tips that are compatible with your pipette. Do not reuse tips to avoid contamination.
Timing of tests: Conduct tests within 30 minutes of preparing the dilution.
Follow dilution ratios: Only use the recommended dilution ratios to ensure measurement accuracy.
For additional support on the required dilutions for acetic acid, malic acid and fructose and using a micropipette correctly, please see our guides here.
Support and Ordering
For all additional help topics and to access the Sentia Customer Support Team, use our Support Portal here. To order strips contact your distributor, or if USA based, see https://sentiaanalysis.com/shop/
Use code SENTIA200 at checkout and get $200 off a Sentia wine analyzer!
The Sentia hand-held wine analyzer measures 6 key analytes during the production process: free SO₂, glucose, fructose, malic acid, titratable acidity and acetic acid. Tests take just minutes, no special skill is required and calibration is automatic. Use in the winery, at the barrel, tank and bottling line – affordable, fast, convenient.
Offer ends 31st December 2023, terms and conditions may apply.
Unified is the biggest wine trade show in North America and that’s why Sentia will be there again in 2024. We want you to be there too, so the purchaser of every Sentia analyzer sold until the end of December 2023, will be eligible for 6 general admission tickets to Unified 2024.
For existing customers, everyone purchasing 5 vials of strips or more in one transaction will be eligible for 2 general admission tickets.
Orders must be placed in November and/or December 2023 to be valid for this offer.
Just complete the form below, upload your order confirmation and we will email you your tickets in December.
Released in 2023 as the sixth test on the platform, Sentia’s acidity method measures the titratable acidity of wine and grape juice all in less than 60 seconds. The UBI patented test strip utilises a salt mediated reduction of H+ to H2, which generates an electrochemical signal that is captured by the Sentia device. Using machine-based learning models, the Sentia intelligence system then correlates this electrochemical signal with the industry recognised titration method commonly called titratable acidity.
However, within the wine industry the terminology used to describe this method is swapped interchangeably between total acidity and titratable acidity, regardless of the titration methods inability to capture the total amount of wine acids within the sample. Adding to the confusion is that the method used to calculate titratable acidity can also change depending on which part of the world you are from.
So how should the wine industry define and describe our acidity measurements in wine, and what are the differences between titratable acidity measurements around the globe?
Definition and measurable differences of total acidity and titratable acidity
There are some slight but significant distinctions between the terms titratable acidity and total acidity that are important to define, in order to understand why confusion arises around these terms when used synonymously.
The definition differences
Titratable acidity measures the amount of carboxylic acid protons in a sample that can be recovered during titration with a strong base (Boulton, R. 1980). In the wine industry, the titrations end point differs usually as a function of the analyst’s regionality of work or education.
Total acidity quantifies all the acidic protons within a sample, both donated and undonated, and therefore captures the entirety of acids present. This can be performed using spectrometry or chromatography laboratory methods.
The definition differences between the two terms are a reason why using the term “total acidity” in place of “titratable acidity” for the general titration method, is technically incorrect.
The measurable differences
Regardless of the definition technicalities, a study by Boulton (1980) also found that the amount of acids recovered by titratable acidity at pH 7.0 was only 74% of the total acids present. To achieve full total acidity recovery, the sample must first be passed through a column with ion-exchange resin and all the carboxylic groups released before the titration step (Rajković, M. et al. 2007). This highlights further that an inherent difference exists between total and titratable acidity and is the second reason why using these two terms interchangeably can be inaccurate.
Measuring titratable acidity in the winery using traditional methods
As the acidic characteristics of juice and wine are determined by relatively weak organic acids (Torress, A.R. et al. 2011), the titration of wines with a strong base will provide a meaningful acidity measurement fit for winemaking purposes. Titratable acidity is also simple enough to be taught to inexperienced personnel and cheap to measure, which is another reason why it is the industry standard adopted for measuring acidity in wine and grape juice. There are also automated titration instruments such as the Hanna Automatic Mini Titrator 230V or the Metrohm 916 Ti-Touch that offer further simplicity if the budget allows.
Regardless of whether you are using a manual or automatic titratable acidity method, all follow the same traditional principle. That is, slowly adding a strong base (usually sodium hydroxide) to a known amount of wine until it reaches a pre-determined end point which allows you to calculate the concentration of acids in the wine. In European countries and as shown in figure two, winemakers titrate to pH 7.0 and express the result as sulfuric acid. In other continents, winemakers titrate to pH 8.2 and express the result as tartaric acid. Results calculated to two different end points and expressed as different acids depending on your global location or educational and work influences, generates another layer of confusion.
Figure 2: An example of a titration of wine with a strong base, in this case, sodium hydroxide at 0.333 M. To calculate the titratable acidity at any given end point, the general formula is: Titratable acidity (g/L) = (75 x conc(NaOH) (M)) x vol(NaOH) (mL)/vol(sample) (mL).
Why do we measure at either titratable acidity at pH 7.0 expressed as sulfuric acid, or titratable acidity at pH 8.20 expressed as tartaric acid?
When titrating wine or juice with sodium hydroxide (the equivalent to titrating a weak acid with a strong base), the equivalence point occurs at a pH above 7.0 (Iland, P. et al. 2004). As pH 7.0 is where the dye indicator bromothymol blue changes colour, this is likely one reason historically that European nations measure to this end point.
Since wine acids are weak organic acids which are reluctant to donate their protons to a base at pH 7.0, some would argue that titrating to a higher pH of 8.2 is more correct, as this is where come donation is complete (FIVS, 2015). For this reason, and the fact a phenolphthalein indicator turns pink at this range as well, many of us choose a pH of 8.2 as our chosen end point when measuring titratable acidity.
As different amounts of base are used to reach each endpoint, the difference in acidity of the same wine being titrated to pH 7.0 and 8.2 is around 6-8% (Boulton, R. 1980). Therefore, comparing a USA based Chardonnay with USA titratable acidity measurement of 6.0 g/L has a very different meaning (and acidity level) to a Riesling grown in Germany with a European titratable acidity measurement of 6.0 g/L as well.
Adding further complexity is that titratable acidity is expressed as though all the available protons were donated from one acid species. Those who measure titratable acidity to pH 7.0 usually express it in units of sulfuric acid, whilst those that measure to pH 8.20 express it in units of tartaric acid, which is the acid of highest concentration in grapes. Nevertheless, both expressions are incorrect and misleading, as the acids encompassed by the titration method incorporates many organic acids.
The major acids captured during wine and grape juice acidity measurements
There are many acids found in wine and grape juice besides tartaric acid, some more prevalent than others. When using Sentia or any titration-based method (even if you call it total acidity) you can expect the following acids to be captured:
Tartaric acid
Malic acid
Succinic acid
Lactic acid
Acetic acid
Citric acid
Of these acids captured, tartaric and malic acids account for the majority within a wine (see figure three). Some studies such as that by Volmer found they accounted for over 90% (2007), whilst another at the Australian Wine Research Institute found this number is more like 60% (Wilkes, E. 2016).
Figure 3: The approximate proportion of acids in red and white wine.) (mL).
Using the two terms total acidity and titratable acidity interchangeably
Regardless of the technical definition differences, the two terms, titratable and total are often used synonymously, even when referring to the same industry standard titration method. That is, titrating a volume of wine with a basic solution to get to a particular pH end point.
For example, the recommended method provided by the International Organization of Vine and Wine (a European based group), calls the measurement of acids in wine total acidity. However, by its method description, it recommends a titration to a pH 7.0 end point. As this method would not recover all the hydrogen ions expected from the acids of grape juice and wine (Boulton, R. 1980), it is understandable then, why calling the titratable acidity method “total acidity” causes confusion for those of us who like chemical definitions.
However, at the end of the day, there is a relatively simple rule to go by.
If you are comparing Sentia to your existing method of measuring acidity, you should consider the chemical reaction occurring. It is likely, regardless of whether you define your historical reference measurement as titratable acidity or total acidity, that you are still titrating your sample with a strong base (or an equivalent method). The Sentia acidity measurement correlates to this titration method in all corners of the globe – that is and as shown in figure one, to the historically used end points of pH 7.0 and 8.2 by a simple selection in the test type screen.
References
Boulton, R. (1980). The Relationship Between Total Acidity, Titratable Acidity and pH in Wine. American Journey of Enology and Viticulture, 31(1), 76 – 80.
Iland, P., Bruer, N., Edwards, G., Weeks., S & Wilkes, E. (2004). Chemical Analysis of Grapes and Wine: Techniques and Concepts. Patrick Iland Wine Promotions Pty Ltd.
FIVS. (2015). Harmonizing Expression of Measurement Results in Wine Analysis: Testing for Total or Titratable Acidity (TA) of Wine. International Wine Technical Summit, Technical Brief.
International Organisation of Vine and Wine. (2023). Compendium of International Methods of Wine and Must Analysis, Volume One. International Organisation of Vine and Wine.
Rajković, M., Novaković, I., & Petrović, A. (2007). Determination of Titratable Acidity in White Wine. Journal of Agricultural Sciences, 52(2), 169 – 184.
Torres, A.R., Lyra, W., Andrade, S., Andrade, R., Silva, E., Araújo, M., & Gaiao, E. (2011). A Digital Image-based Method for Determining of Total Acidity in Red Wines Using Acid-base Titration Without Indicator. Talanta, 84, 601 – 606.
Volmer, D., Curbani, L., Parker, T., Garcia, J., Schultz L., & Borges, E. (2017). Determination of Titratable Acidity in Wine Using Potentiometric, Conductive, and Photometric Methods. Journal of Chemical Education, 94, 1296 – 1302.
Wilkes, E. (2016). Wine Acids, Not Just Tartaric. Technical Review No. 221. The Australian Wine Research Institute, 10 – 13.
Sentia – wine testing made easy during harvest and beyond
With harvest approaching, join us for a 45 minute webinar which will explain why Sentia is the most convenient wine analysis tool available to help you through your busiest time of the year.
Date: July 27th Time: 1pm PDT US
National Sales Manager Pelle Nilsson will introduce Sentia, followed by an explanation of the technical platform by the scientists who developed it. We’ll cover the hardware, software and strip technology which supports tests in just minutes for fructose & glucose, malic acid, titratable acidity, free SO² and acetic acid.
There will be time for Q+A after the presenters so you can be confident you’ll be armed with all the information you need to revolutionise your wine testing. Attendees will be offered a pre-harvest saving on analyzer purchases.
We all know harvest is the busiest time of the winemaking year. Sentia makes it easier by saving you precious time when you need it most. Test fructose, glucose, malic acid and titratable acidity – plus free SO² and acetic acid – in minutes, on a hand-held device. That’s why Sentia is the most convenient wine analysis tool available.
New Sentia customers – save $100 on the Sentia Analyzer promo – SENTIA100 (ends 30 Sept 23)
All customers – Buy any 5 vials of test strips and receive 1 complimentary vial free SO² strips – SENTIA5+1 (ends 31 Oct 23)
