The Vinmetrica Residual Reducing Sugar Assay Kit
Vinmetrica’s newest Residual Reducing Sugar (RRS) Assay Kit allows you to accurately measure residual sugar (glucose + fructose) in your sample. The RRS kit is based on the Rebelein, or “Gold Coast” method in which “reducing” sugars are oxidized by alkaline copper sulfate; the amount of copper remaining is then determined by titration to get an accurate value for residual sugar. Provided reagents will allow you to perform ~30 Residual Reducing Sugar tests.
The new Residual Reducing Sugar assay has been adapted into a convenient procedure for winery use.
Residual sugar (RS) refers to any significant concentration of sugar that is contained in wine, beer or cider at the end of fermentation. Winemakers and brewers are typically most interested in knowing the concentration of the fermentable hexoses glucose and fructose, the main reducing sugars. These determine the level of sweetness of the finished product. At residual sugar levels around 2 g/L (0.2%) or higher, an alcoholic beverage can spontaneously restart fermentation unless it has been properly stabilized.
Note: this kit does not detect sucrose directly. We provide a method for hydrolyzing any sucrose prior to analysis if you want to include sucrose in your results with the RRS kit.
Complete Reagent Kit Includes Everything You Need For Your First 30 Tests.
- Clarifying Powder (PVPP) for decolorizing red wines
- Copper Sulfate Solution
- RRS Binding Solution (Rochelle Salt)
- RRS Titrant (0.20 M sodium thiosulfate)
- RRS Developer Solution (KI)
- RRS (1+5) Sulfuric Acid Solution
- A User Manual
The Kit can be tailored to suit your needs. We recommend purchasing the RRS Kit with the added labware when you first purchase the kit. When you need reagent refills you can simply order the Reagent Kit only. If you do not have a glass burette, lab support stand or burette clamp, you will need to purchase them for this assay. (Bonus: Those three pieces of extra labware can be used with your Free SO2 and TA titrations plus your ABV testing too!)
RRS Labware (purchase the very first time you order the RRS Kit and replenish as necessary):
- Reaction Bottles (2)
- 10.00 mL volumetric pipette
- pipetting safety bulb
- 3 transfer pipettes
- 10 mL sampling pipette
- 5 mL sampling pipette
- 15 mL conical tubes (5)
- Filtration Kit: 5 mL syringe (PN: SC-100-6), 25 mm filter holder (PN: RRS-13), 25 mm filters 15 pieces, (PN: RRS-14)
These Labware items can also be purchased individually. We offer 10 mL glass burettes, burette holders, and lab support stands separately, too.
Simple To Use
- Pretreat sample: filter or decant white wines; red wines need to be decolorized (simple procedure provided).
- Place 2 mL of pretreated wine into reaction flask with 10.0 mL copper sulfate and 5 mL binding solution
- Heat in hot water bath 2.5 minutes. Let cool to near room temperature.
- Add 10 mL acid, and 2 mL each of developer and starch.
- Titrate with the RRS Titrant until black-green color changes to a cream white.
- Calculate g/L reducing sugar from the volume of Titrant used vs. a blank titration.
How It Works
The Residual Reducing Sugar (RRS) test, also known as the Rebelein or Gold Coast Method, determines the amount of residual sugar through the use of excess copper (Cu+2). Reducing sugars are oxidized, reducing the copper. Remaining Cu+2 copper then is converted to iodine, which is titrated with sodium thiosulfate to determine the quantity of residual reducing sugars.
Because of this chemistry, non-reducing sugars are not detected. In general, non-reducing sugars are present in minor amounts in most fermented products and can be neglected. In some cases sucrose may be present in some wines and other beverages; measuring sucrose requires a hydrolysis step; this is described in the manual.
Watch Our How-To Video for the Vinmetrica Residual Reducing Sugar Assay
- Sensitivity and range: detects down to 0.5 g/L reducing sugar in a 2 mL sample; upper limit is determined by dilution (samples with more than about 25 g/L can be diluted as needed)
- Accuracy: 0.2 g/L reducing sugar
- Time to complete: less than 1 hour for up to 10 samples
Simple as that!
For More Details Check Out The:
Residual Reducing Sugar Assay Manual
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