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Affects of sugar and ABV help


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Hi there, we have been having issues with testing the ABV of our gin, we have a few gins that use flavourings, some of these flavourings do have sugar in them. We have 2 different testing machines and they are both coming up with different numbers, we need the percentage to be pretty exact. Does the sugar in the alcohol affect the ABV readings?

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49 minutes ago, Dylan.Daigle said:

Hi there, we have been having issues with testing the ABV of our gin, we have a few gins that use flavourings, some of these flavourings do have sugar in them. We have 2 different testing machines and they are both coming up with different numbers, we need the percentage to be pretty exact. Does the sugar in the alcohol affect the ABV readings?

Sugar definitely will obscure the ABV readings of alcohol.

https://www.ttb.gov/foia/distilled-spirits-gauging-manual#27:1.0.1.1.25.4.504.1

Click this link then click the link under Subpart D titled 'Determination of proof obscuration' Most small distillers I know, including myself, use the distillation method described under 30.32c. A couple hundred dollars on Amazon will get you all the equiment you need to do the laboratory distillation.

Here's a video showing you how to do it. https://www.youtube.com/watch?v=NGrqCZ7ISac&feature=youtu.be

 

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For spirits containing alcohol and water only, you can determine the alcohol content by measuring either the density or the refractive index of the spirit.  Adding sugar will impact on these readings and you cannot use the standard tables.  The sugar changes the density in the opposite direction to the alcohol, but it moves the refractive index in the same direction as the alcohol. These 2 opposing effects can be combined mathematically to determine the abv and the sugar content at the same time.  There are machines from Anton Paar and Rudolph Research that do this, but they are not accepted by the TTB.  Only the lab distillation described by JailBreak is accepted.

What 2 machines are you using currently?

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We currently use Anton paar machines, one is the Alex 500 model and the other is the handheld Snap 41, they both have different ranges and sensitivties, they also both have their limitations, the handheld doesnt do well with testing darker spirits like whiskey, and the alex 500 cant test anything over 50% abv

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The Snap 41 measures SG only and will be confused by the sugar. Ignore the results you get from this unit.

The Alex 500 is designed to measure solids as well as alcohol but the web page does not say how it does it.  The fact that it does not work well for high (> 50 abv) alcohol levels suggests that it is using Refractive Index as its second measurement because I know that the mathematics for combining SG and RI does not work well for high abv.  You should give Anton Paar a call and ask them if the Alex 500 is suitable for your application - I believe that it is.

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Below are some extracts from TTB requirements.

I make a coffee liqueur which has very much in excess of 600 mg of solids per 100 mL

I distill off 250 mL in a glass lab still, if I boil off any more than about 70% of the original volume I find that my condensate goes cloudy and the apparent ABV readings start dropping. I assume that solids are being evaporated as the boiling point increases, and are condensed into my collection flask so re-obscuring the true ABV.

My understanding is 30.32  (c) says the sample must be distilled until there is only 1 or 2 mL left in the flask, but it does not mention the size of the sample. If the original sample was 250 mL<which is quite common, that 1 mL would be charcoal. 

 

§ 30.32 Determination of proof obscuration.

(a) General. Proof obscuration of spirits containing more than 400 but not more than 600 milligrams of solids per 100 milliliters shall be determined by one of the following methods.

..................

(b) Evaporation method. ........................

(c) Distillation method. Determine the apparent proof and temperature of the sample of spirits and then distill a carefully measured sample in a small laboratory still, and collect a quantity of the distillate, 1 or 2 milliliters less than the original sample. The distillate is adjusted to the original temperature and restored to the original volume by addition of distilled water. The proof of the restored distillate is then determined by use of a precision hydrometer and thermometer in accordance with the provisions of §13.23 to the nearest 0.1 degree of proof. ................

 

§ 30.31 Determination of proof.

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(a) General. The proof of spirits shall be determined to the nearest tenth degree which shall be the proof used in determining the proof gallons.

(b) Solids content not more than 600 milligrams. Except as otherwise authorized by the appropriate TTB officer, the proof of spirits containing not more than 600 milligrams of solids per 100 milliliters of spirits shall be determined by the use of a hydrometer and thermometer in accordance with the provisions of §30.23 except that if such spirits contain solids in excess of 400 milligrams but not in excess of 600 milligrams per 100 milliliters at gauge proof, there shall be added to the proof so determined the obscuration determined as prescribed in §30.32.

(c) Solids content over 600 milligrams. If such spirits contain solids in excess of 600 milligrams per 100 milliliters at gauge proof, the proof shall be determined on the basis of true proof determined as follows:

(1) By the use of a hydrometer and a thermometer after the spirits have been distilled in a small laboratory still and restored to the original volume and temperature by the addition of pure water to the distillate; or

(2) By a recognized laboratory method which is equal or superior in accuracy to the distillation method.

........................................

 

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Thanks for the help everyone, really appreciate it. Our solution we came to was to use the Alex 500 for our gin but we run a sample through some paper filters that came with the machine, i think it said 4 micron and it gave us readings .4 below our previous readings, seems to be an efficient way so far

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