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Wine Analysis

 


Starting Sugar | Acidity | Residual Sugar | Percent Alcohol

 

 

 

 

 

 

 

 

 

 

The advancing winemaker as well as the beginning winemaker will want to analyze certain compounds and chemicals in their wine. The list here is by no means exhaustive, but will allow the home winemaker, to measure and understand some of the chemical tests involved with making wine. Some of these tests will be beyond the scope of the small lot home winemaker, as certain unobtainable chemicals are involved, but there are other tests listed here that are at very necessary in making a good balanced wine

Desirable Chemical Tests:

  • Sugar Content Of Must Or Juice
  • Total Acidity Of Must Or Juice
  • Residual Sugar In Wine
  • Percent Alcohol In Wine

Advanced Chemical Tests:

  • Sulfur Dioxide (S02)
  • Malolactic Fermentation Detection

Sugar Content Of Must Or Juice

As was explained in the step by step section, you will use a hydrometer to perform this test. Most hydrometers are calibrated at around 68 degrees, so will want you juice or must to ba as close to this temperature as possible.

  • Fill the hydrometer cylinder or flask with juice or must, avoid bubbles
  • Place the hydrometer into the cylinder and spin slightly
  • Allow hydrometer to float in liquid without touching the sides of the cylinder
  • Read the scale on the hydrometer at the meniscus level
  • A triple scale hydrometer will read in specific gravity, sugar per ounces, and potential alcohol.

Total Acidity

This is a very essential test for making a balanced wine.  Acid effects wine an many ways. It is very helpful in keeping bacteria at bay, and at helping wine to maintain its color. When acid is dissolved in a liquid it separates into two parts. The parts are the hydrogen ion (H+) and the anion (A-) The separation of acid is known as dissociation.  The individual parts can then recombine into un-dissociated acid (HA)  This is the acid that will have the effect on the taste of wine.

Reagents Needed:
Sodium Hydroxide (NaOH)
Phenolphthalein Indicator Solution

White Wine

  • Add 5ml of juice or wine to 75ml of distilled water
  • add 5 drops of indicator solution, shake well
  • Titrate with NaOH until a color change. (Pinkish Color)
  • The amount of NaOH used times .15 equals grams of acid per 100 ml of juice or wine. Also can be calculated in percent tartaric by moving the decimal point of the final reading one place to the left.

Red Wine

  • Add 5ml of wine to 75ml of distilled water
  • do not add indicator instead, titrate with NaOH until the solution turns a blue-green color
  • Add 5 drops of indicator solution
  • Resume titration with NaOH until the color change end point (Pinkish Color)

Residual Sugar

This can be a very elaborate test, and some wineries do take intricate chemical tests to determine this value. For the home winemaker the use of a dextrocheck kit will suffice. I have calculated percentages in place of specific gravity before, and just winged it on the residual sugar percentage for a competition before.

Dextrocheck Kit:

  • Decolorize your wine with charcoal
  • Add 1 reagent tablet to 0.5 ml sample of decolorized wine
  • After tablet has dissolved, read color against the scaled provided with kit.

Percent Alcohol

Just Do The Math = Starting specific gravity minus Final specific gravity Divided by .0074 = percent alcohol in finished wine

Example.  1.090 - .995 = .095 / .0074 = 12.8% alcohol

Another Way, Starting percent sugar minus finished percent sugar multiplied by 0.57

Sulfur Dioxide

This is an advanced chemical test, and is beyond the scope of most home winemakers. Some wine supply shops now carry simplified titrette tests that can be done by the home vintner, but I am not sure how accurate these tests are. Sulfur dioxide (S02) in wine is eventually converted to sulfuric acid, and the simpler tests use this osmoses to calculate S02 levels in a wine. The advanced method of determining the S02 levels in wine is called the ripper method, and a brief description of this method is as follows.

Reagents Needed:

 

 

 

Malolactic Fermentation