Read the instructions carefully to avoid any problems. The hydrometer we all use when measuring Brix or specific gravity SG is a practical instrument to monitor the rate of fermentation.
It provides a good indication of when fermentation is complete in dry wines, usually when the reading is This is not a measurement of residual sugar concentration, but rather an indication of the possibility that sugar is still present.
At this low range, the hydrometer only provides a rough approximation of sugar content. The measurement is affected by the presence of other solids in the wine sample, as well as alcohol and carbon dioxide. With little sugar in the wine, dissolved solids other than sugar play a larger role in determining how high the hydrometer floats compared to times when sugar is more abundant for example, prior to fermentation.
To minimize error when using a hydrometer, reduce the amount of solids in the wine by passing the sample though through a paper filter, such as a coffee filter. Pour the sample in the cylindrical tube with the hydrometer already inside. The sample should reach close to the top of the tube. Give the hydrometer a couple of fast spins to eliminate as much carbon dioxide gas as possible, then take a hydrometer reading at eye level.
The sample should be measured at the temperature indicated on your hydrometer. Use a small wine thermometer to determine the temperature of the sample. If the temperature is too high, cool the sample by placing the container in a fridge or a cold-water bath. If it is too low, apply some heat or place the container in a hot-water bath.
A narrow-range hydrometer with smaller graduations can also be used to improve accuracy of measurements. For example, you can buy a hydrometer with a range of negative five to positive five Brix with 0.
Other laboratory methods for determining residual sugar concentration are available; the Rebelein method is probably the most popular and widely used in commercial wine analysis. These advanced methods provide more accurate results and can measure higher concentrations of residual sugar; however, they require the use of chemicals not readily available to home winemakers.
The required chemicals can be found at chemical supply shops or research laboratories. In the Rebelein method, a laboratory process — termed copper-ion reduction — is used to determine residual sugar concentration. A wine sample is mixed with a copper sulfate solution and an alkali salt solution made from sodium potassium tartrate and sodium hydroxide.
After a rapid boil, potassium iodide and sulfuric acid solutions are added to the mixture and it is then titrated with sodium thiosulfate. The residual sugar concentration is determined by the amount of titrate used in titrating the wine sample compared to titrating a water sample.
For more information on these methods, consult any advanced wine analysis textbook. Zoecklein, K. Grape Varieties. Region Guides. Tasting Guides. Sweetness in Wine. How to detect sweetness. How does a wine become sweet? Pairing with sweetness.
How sweetness is measured. How sweetness affects a wine's aging potential. Acidity How tangy a wine is. Tannins, says Hanni, are astringent and dry your mouth out, much like if you sucked on a tea bag. So a big red wine with heavy tannin levels might have residual sugar, yet feel dry.
The tannins provide a sensory distraction that takes attention away from the sweetness. Some artificial sweeteners taste metallic to some tasters. There are other sweet compounds in wine that taste sweet, but are not measured by residual sugar.
So that answers how a technically bone-dry wine may seem sweeter than a wine with twice as much [residual sugar]. The combination of alcohol, perception of alcohol and potentially sweet amino acids contribute to the perception of sweetness that is not measured by sugar. One more point: very ripe fruit can convey an impression of sweetness even in a wine that was fermented completely dry.
Subscribe to Wine Enthusiast Newsletters Get the latest news, reviews, recipes and gear sent to your inbox. Published on September 21, One big and laudable exception is Canadian riesling. Often producers will helpfully label them as "off-dry" to distinguish slightly sweet styles from the dry riesling.
The best rule of thumb and I'm sorry to say it's sorely inadequate is to check for alcohol content. If the wine weighs in at 11 per cent or lower, chances are it's at least a little sweet. Low alcohol tends to mean the yeast did not finish the job of converting sugar to alcohol. Less alcohol usually equals more RS. In the end, sugar is just a rough gauge of whether the wine will taste sweet or not.
It's a question of balance. Some per-cent-alcohol wines can taste subtly sweet, not because they contain much sugar but because they're either very fruity a flavour often confused with sweetness or because they lack sufficient acidity to create a sensation of total dryness. Australian shiraz is a good example; it can taste vaguely sweet even when it's technically dry.
E-mail your wine and spirits questions to Beppi Crosariol.
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