Reducing Sugars

Parameter Selection

Application Importance of Measuring Reducing Sugars in Wine

During alcoholic fermentation, yeast consume sugars found in the grape juice or must and convert it to ethyl alcohol and carbon dioxide. In the case of certain styles of wine such as semi-sweet or dessert wines, some sugar is allowed to remain post-fermentation. This residual sugar can serve to provide a sweeter character to the final blend or play a role in microbial stability.

The primary fermentable sugars found in grapes are glucose and fructose. These two simple sugars are also known as reducing sugars because they contain functional groups capable of being oxidized under certain conditions. A winemaker interested in confirming the residual sugar content of a product post-fermentation, or a finished wine product, can use a redox titration to facilitate the oxidation and analysis of these sugars.

For this titration, an alkali solution of copper complex, known as Fehling’s reagent, is combined with a sample of wine. Catalyzing the reaction with heat, the reducing sugars present reduce the copper from Cu(II) to Cu(I). Potassium iodide is added to reduce any excess Cu(II), resulting in iodine as a product. The iodine, present in an amount equal to the residual Cu(II), is then titrated with sodium thiosulfate to determine the original amount of residual sugar present in the wine sample. The results are reported as g/L of reducing sugar.

Meters

HI902 Potentiometric Titration System for Reducing Sugars

The HI902 is a potentiometric titration system for the measurement of Reducing Sugars and other wine parameters. This meter has many features including:


  • Can be used for YAN, SO2 (Air Oxidation and Ripper Methods), and titratable acidity titrations
  • Available with 1 or 2 analog input boards. Each board can accept ORP, pH or ISE electrodes. Having two analog board inputs allows for the simultaneous connection of two probes.
  • Available with 1 or 2 dosing pumps. A second dosing pump can be used for:
    • Second titrant for a second parameter
    • Reagent addition as part of the sample preparation
  • Exchangeable Clip Lock burettes allow for quick changing to different titrants and are available in variety of sizes up to 50 ml
  • Linear or dynamic dosing of titrant with 40,000 step burette
    • Dynamic dosing allows for larger doses in the beginning of the titration and smaller as the end point is reached
    • Accurate and precise determination of titrant used
  • Logging and USB connection for data management
  • Compatible with HI921 autosampler for users with a high throughput of samples to be measured
  • Factory installation, training and service plans available
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HI902 Potentiometric Titration System for Reducing Sugars

The HI902 is a potentiometric titration system for the measurement of Reducing Sugars and other wine parameters. This meter has many features including:


  • Can be used for YAN, SO2 (Air Oxidation and Ripper Methods), and titratable acidity titrations
  • Available with 1 or 2 analog input boards. Each board can accept ORP, pH or ISE electrodes. Having two analog board inputs allows for the simultaneous connection of two probes.
  • Available with 1 or 2 dosing pumps. A second dosing pump can be used for:
    • Second titrant for a second parameter
    • Reagent addition as part of the sample preparation
  • Exchangeable Clip Lock burettes allow for quick changing to different titrants and are available in variety of sizes up to 50 ml
  • Linear or dynamic dosing of titrant with 40,000 step burette
    • Dynamic dosing allows for larger doses in the beginning of the titration and smaller as the end point is reached
    • Accurate and precise determination of titrant used
  • Logging and USB connection for data management
  • Compatible with HI921 autosampler for users with a high throughput of samples to be measured
  • Factory installation, training and service plans available
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HI83746 Portable Reducing Sugar Photometer

HI83746 portable photometer uses cupric tartrate Fehling reagents (cupric tartrate ) to react with the reducing sugars (i.e. glucose, fructose) to produce a colored product that varies in intensity to the concentration of reducing sugars. The resulting color is measured by a filter photometer at 610 nm.

When the reducing sugar content is known at the beginning of fermentation, the potential alcohol degree can be estimated multiplying the sugar concentration (in g/L) by 0.06.

  • Fehling reagent to measure reducing sugar
  • Measures up to 50 g/L
  • Prepackaged chemistry for analysis
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Titrants

Titrants for Potentiometric Titrators

Titrants and reagents used in reducing sugars titrations include sodium thiosulfate, Fehling’s solution, sulfuric acid, sodium hydroxide, and potassium iodide. These titrants and reagents can be used with all potentiometric titrators that allow customized methods with differing concentrations of titrant.


  • Titrants available in different concentrations for multiple measurement ranges
  • Complete line of titrants and reagents to perform sulfur dioxide titration by either the Ripper or air oxidation methods
  • Can be used with any potentiometric titration system in which the user has control over the strength of titrant used
  • Produced to ISO 9001 standards
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Titrants for Potentiometric Titrators

Titrants and reagents used in reducing sugars titrations include sodium thiosulfate, Fehling’s solution, sulfuric acid, sodium hydroxide, and potassium iodide. These titrants and reagents can be used with all potentiometric titrators that allow customized methods with differing concentrations of titrant.


  • Titrants available in different concentrations for multiple measurement ranges
  • Complete line of titrants and reagents to perform sulfur dioxide titration by either the Ripper or air oxidation methods
  • Can be used with any potentiometric titration system in which the user has control over the strength of titrant used
  • Produced to ISO 9001 standards
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Electrodes

HI3148 Wine Must ORP Electrode

There are many considerations that are used when designing an ORP electrode for a specific application. With wine juice and must there is a high solids content that can lead to the clogging of the reference junction resulting in erratic readings.

  • PTFE Sleeve Junction
    • Repels solids to reduce clogging
    • Movable to clean the interface between sample and reference
  • Double Junction Design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Refillable with 3.5M KCl
    • Extends life of the electrode by being able to replenish the electrolyte fill solution as opposed to a gel filled that cannot be refilled
  • Platinum ring sensor
    • Better detection due to a larger surface area than a pin design
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HI3148 Wine Must ORP Electrode

There are many considerations that are used when designing an ORP electrode for a specific application. With wine juice and must there is a high solids content that can lead to the clogging of the reference junction resulting in erratic readings.

  • PTFE Sleeve Junction
    • Repels solids to reduce clogging
    • Movable to clean the interface between sample and reference
  • Double Junction Design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Refillable with 3.5M KCl
    • Extends life of the electrode by being able to replenish the electrolyte fill solution as opposed to a gel filled that cannot be refilled
  • Platinum ring sensor
    • Better detection due to a larger surface area than a pin design
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HI3131 Laboratory ORP Electrode

The HI3131B is a standard laboratory ORP electrode that is commonly used on benchtop mV/ORP meters. The glass body is a good conduction of temperature allowing the reference cell to equilibrate with temperature of the sample . The HI3131B is a refillable ORP electrode.

  • Glass body
    • Fast thermo-equilibrium with sample
    • Easy to clean
  • BNC Connector
    • Universal connector that can be used with any meter that accepts a BNC connection
  • Refillable with 3.5M KCl
    • Extends life of the electrode by being able to replenish the electrolyte fill solution as opposed to a gel filled electrode that cannot be refilled
  • Double Junction design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Ceramic junction
  • Platinum Pin Sensor
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HI3230 PEI Plastic Body ORP Electrode

The HI3230B is a rugged PEI plastic body ORP electrode with a universal BNC connector. The chemically resistant plastic protects protects this probe from accidental breakage. The HI3230B is gel filled so no refill solution is required.

  • Polyetherimide (PEI) plastic body
    • High grade chemically resistant plastic
    • Unbreakable
  • BNC Connector
    • Universal connector that can be used with any meter that accepts a BNC connection
  • Gel filled
    • Maintenance free with no refill solutions required
  • Double Junction design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Ceramic junction
  • Platinum Pin Sensor
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HI3230 PEI Plastic Body ORP Electrode

The HI3230B is a rugged PEI plastic body ORP electrode with a universal BNC connector. The chemically resistant plastic protects protects this probe from accidental breakage. The HI3230B is gel filled so no refill solution is required.

  • Polyetherimide (PEI) plastic body
    • High grade chemically resistant plastic
    • Unbreakable
  • BNC Connector
    • Universal connector that can be used with any meter that accepts a BNC connection
  • Gel filled
    • Maintenance free with no refill solutions required
  • Double Junction design
    • Silver free reference in outer reference cell that will not react with any sulfides present to form an insoluble silver sulfide that will clog the reference junction
  • Ceramic junction
  • Platinum Pin Sensor
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Maintenance Solutions

ORP Test Solution

ORP test solutions are used for testing the performance of an ORP electrodes. When the ORP electrode is placed in the test solution the reading displayed will help the user know when to clean or replace the ORP electrode.


  • If the mV reading is 240 ± 20 mV this indicates the electrode is in good condition and can be used for titration
  • A mV reading of 240 ± 30 mV indicates the electrode is beginning to drift. The electrode should be cleaned and conditioned.
  • If the mV reading is greater than 240 ± 40 mV then the electrode should be replaced
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ORP Test Solution

ORP test solutions are used for testing the performance of an ORP electrodes. When the ORP electrode is placed in the test solution the reading displayed will help the user know when to clean or replace the ORP electrode.


  • If the mV reading is 240 ± 20 mV this indicates the electrode is in good condition and can be used for titration
  • A mV reading of 240 ± 30 mV indicates the electrode is beginning to drift. The electrode should be cleaned and conditioned.
  • If the mV reading is greater than 240 ± 40 mV then the electrode should be replaced
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ORP Electrode Refill Solutions

Maintaining a proper filling solution level in a refillable ORP electrode is critical to obtaining accurate and reliable ORP measurements. The solution not only provides an electrical pathway to the internal reference but maintaining an ideal level ensures there is adequate head pressure to ensure flow through the junction into the sample.

  • Solutions for both single and double junction electrodes
    • Single junction electrodes use 3.5 M KCl with silver chloride
    • Double junction electrodes use 3.5 M KCl
  • Available in a variety of sizes
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Cleaning Solutions

Maintaining a clean ORP electrode is critical to obtaining accurate and reliable measurements. This especially true for Winemakers that use an ORP electrode with a grape juice sample that has a high content of solids from the skins and pulp of a crushed grape. Hanna offers specially formulated solutions to clean the deposits and stains from a ORP electrode and the reference junction.


  • Specially formulated to remove wine deposits and stains
  • Available in 500 ml bottles or single use sachets
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Cleaning Solutions

Maintaining a clean ORP electrode is critical to obtaining accurate and reliable measurements. This especially true for Winemakers that use an ORP electrode with a grape juice sample that has a high content of solids from the skins and pulp of a crushed grape. Hanna offers specially formulated solutions to clean the deposits and stains from a ORP electrode and the reference junction.


  • Specially formulated to remove wine deposits and stains
  • Available in 500 ml bottles or single use sachets
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Storage Solutions

All combination ORP electrodes have a junction between the reference cell and sample. Different junction types have different porosities that will affect the time takes to be hydrated. Maintaining the hydration of the junction allows for a stable liquid junction potential which is critical for accurate and repeatable readings.

  • Keeps ORP junction hydrated for fast response
  • Available in 230 and 500 ml bottles
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Lab Supplies

Lab Supplies

Laboratory Supplies for reducing sugar analysis include the HI83099 COD reactor for the digestion of reagent used with the portable photometer. Other accessories used include pipettes, pipette tips, and replacement cuvettes.

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Lab Supplies

Laboratory Supplies for reducing sugar analysis include the HI83099 COD reactor for the digestion of reagent used with the portable photoeter. Other accessories used include pipettes, pipette tips, and replacement cuvettes.

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Resources

Check out our Media Library and Knowledge Base pages specifically for wine and wine related products.