Lower Alcohol Content

[Brewlord]

As a complete reversal of the last topic posted....

Just a question on alcohol content

I generally brew using cans of concentrate and variants of Coopers 1kg brew enhancer No.2 for convenience above all else.

I have had really good results so far (following all the rules of course) but have decided to make up a less fun lower alcohol content brew in preparation for the Xmas season (I know, I know - you are all thinkingwhy would you want to but you know the old saying Drink, Drive youre a bloody idiot). All the literature I have come across indicates using less sugar will generally achieve the required results.

As I have read and interpreted from this forum before, I decided to use approx half of the 1kg pack of sugar in my last two brews but curiously the OG has been 1.070 and 1.082. From my experience gained so far and things I had read, I had thought that less sugar should equal lower OG.

By way of clarification, when I use the full 1kg I have an OG of normally 1.054 to 1.062. With this reading and my FG reading I come up with what I expect in ALC / VOL using the formula OG - FG + 0.5 divided by 7.46. (I got this from this and numerous other websites and with all the other information I had come across it seemed to be a good way of working the ALC content out.)

Using the above formula with half the sugar (and therefore higher OG as described above) I end up with a higher final ALC content calculation. I am however achieving a lower FG reading using half the sugar (around 1.006) over a shorter time (4 days instead of 7) which is good and also seems to say all the sugar is being fermented. (Using the full 1kg of sugar I am getting a FG of about 1.010 to 1.012)

I also check my hydrometer calibration regularly against water (20 deg C to calibrate at 1.000.)

I guess my questions are am I actually brewing a lower alcohol content beer by using half the sugar? And / or is my method of calculation incorrect?

Thanks

PS. Throughout its brewing I tasted and have now bottled the first of my lower fun brews and so far it has tasted, looked and smelled great. The second is still a work in progress.

 

[sluggerdog]

Yeah that does not sound right. The lower amount of sugar should equal a lower SG.

Are you using the same amount of water for both brews? Or was the kit and sugar really stired in well?

 

[Brewlord]

Yeah that does not sound right. The lower amount of sugar should equal a lower SG.

Are you using the same amount of water for both brews? Or was the kit and sugar really stired in well?

Thanks for response Sluggerdog...yeah I try to be a bit meticulous about water amounts and the levels may only vary bu plus or minus 1 litre. Also, I make sure everything is very well stirred (to theh point of almost exposing the wort too long) and that the sugar is fully disolved before topping up

 

[Adamt]

The OG is (roughly) related to the amount of "food" you put into your fermenter, divided by the size of the batch. Food can be anything from sugar, honey, dry malt extract, tinned kits, etc. Halving the batch size doubles the OG, and halving the amount of "food" halves the OG. (By halving i mean the numbers after the 1, i.e. 1.080/2 = 1.040, not 1.080/2 = 0.540)

The FG is related to how much food is left over/rejected by the yeast. As you have observed, sugar ferments really well and all of it gets eaten, however malt extracts leave some stuff behind, which we call "body". Body is a good thing, it gives you head retention and mouthfeel.

You said you used half a kilo of sugar and got 1.070 and 1.082. What other food did you add to that, and how big was the batch? What about with the batches with a whole kilo of sugar?

There are a few calculators going around which will determine the OG, FG and alcohol content based on your ingredients and batch size, don't have the URLs handy unfortunately.

You could get a program like Beersmith (www.beersmith.com) and fiddle around with that, just choose your batch size and add extracts and that should give you a rough idea.

 

[DJR]

I think you have the basics down, but i'd say you either need to check your total wort volume (are you diluting the same), and also check again when taking a reading as sometimes the tap can get clogged up with extract and give you a higher reading than you'd expect.

Also, your formula for calculating alc by vol should be (OG - FG) / 7.46 + 0.5. The 0.5 is from bottle conditioning and usually actually only adds 0.3 rather than 0.5% alcohol.

 

[Brewlord]

The OG is (roughly) related to the amount of "food" you put into your fermenter, divided by the size of the batch. Food can be anything from sugar, honey, dry malt extract, tinned kits, etc. Halving the batch size doubles the OG, and halving the amount of "food" halves the OG. (By halving i mean the numbers after the 1, i.e. 1.080/2 = 1.040, not 1.080/2 = 0.540)

The FG is related to how much food is left over/rejected by the yeast. As you have observed, sugar ferments really well and all of it gets eaten, however malt extracts leave some stuff behind, which we call "body". Body is a good thing, it gives you head retention and mouthfeel.

You said you used half a kilo of sugar and got 1.070 and 1.082. What other food did you add to that, and how big was the batch? What about with the batches with a whole kilo of sugar?

There are a few calculators going around which will determine the OG, FG and alcohol content based on your ingredients and batch size, don't have the URLs handy unfortunately.

You could get a program like Beersmith (www.beersmith.com) and fiddle around with that, just choose your batch size and add extracts and that should give you a rough idea.

The only other 'food' is what is in the can of concentrate. Cant say I am halving the food but definitely lowering the amount and therefore by your equation 'should' be lowering the OG but instead it is higher. I keep all my batches to the same volume (23 litres plus or minus 1 litre) and this also goes for when I use a full 1 kg of sugar. I was also thinking that some concentrate may be stuck in the tap giving a higher reading but I do exactly the same amount of stirring for every batch and have only come across this anomaly of higher OG readings when using half the sugar. Still a bit confused but I think the brew will turn out OK but with an unknown but possibly lower alc content.