Dear Bharat,

1-USING SPECIFIC GRAVITY

Calculating the alcohol content of a wine that you made is always fun. While amateur wine makers don’t need to report this value to anyone it’s just neat to know how much alcohol you’ve produced.

Winery determining alcohol content through distilling.

 There are many formulas out there for calculating the percent alcohol of wine and beer. You may have noticed that they’re not the same. Largely this is because the relationship between the specific gravity and the amount of alcohol produced is not linear.

What this means is that specific gravity and alcohol content have a complex relationship that is not easily represented with a simple equation. Non-linear equations can be pretty nasty to deal with.

To get around these nasty but accurate equations simpler equations have been developed but they are only relevant for a small range of alcohol content. Wine, typically has an alcohol content of around 11-15% while beer is usually around 5-6%. Because of this they each have their own alcohol content equation based on these different ranges of alcohol.

In short be sure that you’re using an equation specific to wine making. A beer equation can lead to incorrect results.

 The simplest way to calculate your alcohol content is with a calculator. You’ll need to know your starting or original specific gravity that you took before fermentation began. Also, you’ll need the final specific gravity taken once your wine has finished fermenting and is stable. Just plug in both values and press calculate.

 Original Specific Gravity:

Final Specific Gravity:

 % Alcohol by Volume:

 This is about as accurate as you can get with the equipment and methods available to amateur wine makers. Wineries use distilling equipment as shown above to get a more exact alcohol content.

To ensure that you get as accurate a result as you can you need to take accurate specific gravity readings. Also, be sure to do your temperature corrections for the greatest accuracy.

Check out this article and calculator for correcting your specific gravity readings for temperature.

 For those of you who’d like to know the equation behind the calculator here it is.

 It’s simple enough to use in a spreadsheet or calculate by hand. Note, that this equation yields wine alcohol content as a percentage of alcohol by volume. There are other equations for alcohol by weight, however, wine alcohol content by volume is the most prevalent way to report alcohol levels.

Please use the following link to start doing your specific gravity calculations:

http://winemakersacademy.com/wine-alcohol-content-calculator/

2-USING HYDROMETER

How To Determine Your Wine's Alcohol Level.

Posted on October 13, 2015 by Ed Kraus There have been 13 comment(s)

This is the question every budding home wine maker wants to know, "How can I tell how much alcohol is in my wine?" The problem is, this question is usually asked about the time they're ready to bottle their wine.  Unfortunately, for the amateur winemaker, this is far to late in the process to make any accurate determinations.

What Needs To Happen

The easiest way to know how much alcohol is in your wine is to take two readings with what's known as a wine hydrometer: one reading is taken before the fermentation has started and the other reading is taken after the fermentation has finished. By comparing these two hydrometer readings you can determine – with great accuracy – how much alcohol is in your wine.

Very simply put, a hydrometer is a long, sealed glass tube with a weight on one end. By observing how high or low it floats in a liquid you can determine a reading.

"And what are we reading?" Essentially, we are trying to figure out how much sugar is in the wine or wine must. The higher the wine hydrometer floats, the more sugar there is in the liquid, and the opposite holds true as well.

During a fermentation, sugar is what yeast turns into alcohol. If we know how much sugar there was in the wine must before the fermentation, and we know how much sugar there is in the wine after the fermentation, we then know how much sugar was consumed by the yeast during the fermentation. From this information we can determine how much alcohol was made during the fermentation and is now in the wine.

It all sound complicated when it is all explained in detail this way, but in practice it is very easy to accomplish. All you need to do is:

1. Take a wine hydrometer reading at the same time you add the yeast to your wine must. The hydrometer has a scale along it called "Potential Alcohol". At this point in the wine making process you should be getting a reading of around 10% to 13%. The reading is the point where the surface of the liquid crosses the scale. This reading indicates how much alcohol the wine can have if all the sugars are fermented. Write this number from the gravity hydrometer down and save it for later.

2. Take another reading with the hydrometer once the fermentation has completed. This reading should be somewhere around +1 to -1 on the Potential Alcohol scale. By comparing these two gravity hydrometer readings you can determine your wine's alcohol level. Take the first number you wrote down and from that, subtract the second number.

The Calculations

As an example, if your reading before the fermentation was 12% and the reading after the fermentation was 1%, this means that your wine has 11% alcohol (12 minus 1). If your first reading was 12% and your second reading was -1%, that means your wine has 13% alcohol (12 minus -1).

Another way to think of it is you are monitoring how far along the wine hydrometer's Potential Alcohol scale the fermentation is traveling. It started at 12 and ended up at -1. That's' 13 points along the scale.

Further Information

You can find more information about using a hydrometer to make wine in the book, "First Steps In Winemaking." Also, the article, "Getting To Know Your Hydrometer" as lot additional information about using your hydrometer when making wine.

- See more at: http://www.eckraus.com/blog/how-to-determine-your-wines-alcohol-level#sthash.L4jOBqlp.dpuf

http://www.eckraus.com/blog/how-to-determine-your-wines-alcohol-level

Hoping this will be helpful,

Rafik

GC-FID is also used to analyse alcohol content in wine, beer and other alcohol drinks. whole process is straight forward, simply dilute wine with D.I water inject into GC-FID and compare peak area against to Certified Ethyl Alcohol standard solution.

Dear Bharat,

In our laboratory we work with two methods:

1. Ebulliometer (commonly used in small and medium wineries in Brazil), easy to use, according to manufacturer's instruction.

2. Digital densitometer (used in large wineries and research because it has a higher precision) requires distillation before reading.

There are other methods as alcoholometer, pycnometer, GC, HPLC and NIR, which may be useful.

Best regards,

Prof. Alessandro Nogueira