Hot answers tagged specific-gravity
16
If brewing all-grain, taking gravity readings after mashing allows you to calculate your mash efficiency. If your efficiency is low (meaning you're not getting good conversion), you can use this knowledge to pin down problems in your recipe, milling, and mash/sparge processes.
Measuring the gravity before and after fermentation allows you to calculate the ...
12
Perceived sweetness has a lot to do with balance. A beer with an FG of 1.025 sounds sweet based on that number, but if the IBU level is high or, better yet, well balanced, the beer won't be cloying. Similarly and coversely, a beer that finishes nearly dry at, say, 1.005 could taste quite sweet if the IBUs are low and the alcohol content is high. Alcohol ...
10
In order to be able to calculate fermentation temperature, an exothermic process, we need to know how much heat (H) is "evolved" as yeasts convert sugars to alcohol. Digging around in the literature I found this article (1).
Although its focus is bioethanol production, it does give some figures in terms
of joules per mole which we can use to do the ...
10
You certainly can. This is, for example, how you use a pycnometer. But, it's a bit of work. Two major problems:
1) You need to find a way to measure volume very, very precisely. The scales are reasonably accurate, but it is unlikely that you own a volumetric device accurate enough. Your SG will be screwed by an entire point for every 0.1% margin of error.
...
9
Almost one third of your gravity is coming from maltodextrin powder. This stuff is non fermentable and should be used at a lower percentage. Also whatever yeast came with the kit is possibly old and unreliable.
You probably won't get this batch to go any lower but you can make a couple changes and brew it again.
Use only 5-10% of the total gravity ...
7
Yup, it can be easily measured using a hydrometer. Simply take a specific gravity reading before pitching yeast and after fermentation is complete. Find the difference between the two values, this will be proportional to the amount of sugar the yeast has converted to alcohol. Multiply this number by 131 and you get the ABV. For example:
You brew a ginger ...
7
It sounds like you had a very active fermentation. It is not uncommon for the majority of fermentation to be complete in a few days. Commercial breweries strive for this. HOWEVER, this does not mean that the yeast are done with your beer! Even after fermentation is complete, the yeast will clean up after themselves, reducing things like diacetyl. (which ...
7
Pure sugar is the most fermentable substance, at 1.046 points per pound per gallon. With 12 pounds of sugar in 3 gallons, you'd expect a OG of 1.183. Honey has an estimated yield of 35 ppg, and correspondingly the gravity would be lower - 1.135.
There could be 3 possibilities for the observed high gravity
the stratification is causing the reading to be ...
7
Here's some tips on getting an accurate hydrometer reading:
check the hydrometer is calibrated, by checking that water reads 1.000 at the calibration temperature (either typically 65F or 20C). I've tried both distilled water and tap water and by both read the same.
when taking a sample from a extract-based brew, particularly partial boil where top up water ...
6
A # that big strictly sounds like mixing errors to me. Stratification of warm wort and cold top off water happens alot. You need to shake vigorously anyway to get some aeration into the fermentor. Take your gravity readings after that step in the future.
Also, if you used 2.5 gallon of water for the boil and 3 gallons to top off, what happened to the ...
6
A refractometer works on the principle that a sugar solution has a different index of refraction than water, thus the concentration of a sugar solution can be determined with the instrument.
Due to the relatively similar indices of various sugars, it will measure all sugars, as well as other non-fermentables.
Because ethanol has a very different refractive ...
6
If we steal the numbers from this question, we can assume that liquid malt extract has a value of about 37 points per pound per gallon, and dry has about 44. This is not exact.
total gravity points needed = Desired total gravity - current total gravity
total gravity points needed = 47 * 5 (desired reading * desired volume) - 37 * 5 (current reading * ...
6
A non dissolvable solid like yeast in a liquid does not increase specific gravity. Its like dropping stones in to a water, the water still has the same density as it did before as the stones (and yeast in your example) are two separate phases. The solids simply displace the liquid but do not become a "part" of it, as in the example of salts or sugars or ...
5
I have brewed many batches where I never checked the gravity in the past. You don't really need to check the gravities to make great beer. You do run the risk of not knowing when a beer is complete and maybe having overcarbonation issues in the bottle. But good fermentation practices should, normally, take care of that.
However, I think that when you get ...
5
I don't take readings throughout fermentation but some people do. There is an increased risk in collecting samples, but if your sanitation practices are good, the risk is low. I don't recommend dropping the hydrometer in. It will hard to find among the krausen, will be very difficult to read accurately, and the reading will be slightly off due to co2 that ...
5
All temperatures are in expressed in degrees F.
correction = 1.313454 - 0.132674*F + 0.002057793*F*F - 0.000002627634*F*F*F
SG_corrected = SG + (correction * 0.001)
http://www.primetab.com/formulas.html
agrees with http://brewery.org/library/HydromCorr0992.html
5
You may not be able to get it lower without using enzymes. Maltodextrin is non fermentable, and most dark malts have a large amount of non-fermentables from the kilning process.
Adding some dry beer enzyme or beano will break down the complex sugars in the dark malt, and some of other nonfermentables, but you may end up with a thin beer afterwards.
A more ...
5
1.020 is quite a high final gravity. It sounds like your fermentation is stuck. I would swirl the fermenter to resuspend the yeast (without introducing any air) and see if fermentation resumes. If that fails, then I would buy more of the same yeast that you originally pitched, if it's dry yeast rehydrate it in 90-100F water (32-38C) for 15 minutes, then ...
5
An OG reading of 1.12 seems about double what you would expect for that grain bill, and gravity is only really affected by dissolved solids. Obviously the first thing you should do is check your hydrometer to make sure it is accurate, that is almost certainly the cause of the error.
In water the specific gravity should read 1.00 since specific gravity is ...
4
Assuming you are using the hydrometer right:
It could be your efficiency in the steep. If that is the case you are working at 64% efficiency instead of 72% like the recipe says. ( 70 GU * 0.72 efficiency / 78 GU = 64.6% ) Rinse the grain bag with hot water around 170ยบ. That will get more sugar out of the grain.
How much wort did you get? If you ended ...
4
You can take measurements throughout fermentation to find out how fermentation is going. I would recommend a wine thief.
http://www.midwestsupplies.com/fermtech-wine-thief.html
Just sanitize it before you stick it in your fermenter.
I generally just check gravity readings when I'm racking from primary to secondary and from secondary to keg so that I ...
4
Not really. In a discussion of the subject on the AHA forum recently, it was brought up that using barrels will increase the "angel's share"...the beer that evaporates. But it's such a small amount that it's negligible in terms of increasing the alcohol. Using chips or cubes should have no effect whatsoever.
4
For fruit, get a refractometer. $50 or so online at williamsbrewing.com or other beer/wine shops. Mash up a handful of the fruit 'til it's juice and then dribble the juice on the refractometer lens. That will give you a brix reading. There's probably some formal math you can use to get exact numbers here, but here's some basic info: 24 brix when ...
4
I use both because my refractometer reads Brix (plato), but I "grew up" on SG and I often take my FG with a hydrometer, so I'm used to SG. There is also a good rule of thumb for determining alcohol content with SG. Drop the 1 and move the decimal place to the second to last place and that will approximate ABV. In other words, if you brew a 1.067 beer and get ...
4
If you're talking about a sample of wort before you've pitched the yeast, then I think the only thing to skew a next-day reading would be a wild yeast or bacteria.
If you're talking about a sample of fermenting beer, then the yeast will be making the gravity go lower while the sample sits waiting for you to read it.
4
Personally I use a small graduated cylinder to take readings. You fill the cylinder to just below the top and then when you put your hydrometer in, a small amount spills over but the hydrometer reading and top of the beer level are all at the top of the cylinder. (the slight spill over gets rid of foam) I will also then simply drink what is in the cylinder ...
4
If you got consistent hydrometer readings over several successive days then yes, go ahead and bottle. 3+ weeks in the fermenter sounds like more than sufficient time for your IPA.
By the way, the bubble rate is not an accurate way of measuring fermentation activity. Bubbles can be produced by changes in ambient temperature and by simply walking past your ...
4
You can use a wine or beer thief and a test jar to grab a sample from your carboy.
I use the following one and it works great: http://www.amazon.com/Fermtech-Wine-Beer-Thief/dp/B00186ADYS This one is nice because the hydrometer fits right inside it so you don't need a test jar.
I never put the sample back in, just scared of contamination. Does anybody ...
4
A late malt addition doesn't affect final gravity. The only difference compared to a regular addition is that a 1 hour boil alters the flavor and color of the extract to a small degree. (The wort gravity will also be different for most of the boil, affecting hop utilization, but since the recipe states a late addition, this will have been taken into ...
4
(TOG - GR * (BV/FV)) / (45/FV) = lbs of DME to add pre-boil to hit target OG
TOG = Target Original Gravity in Points
GR = Gravity Reading in Points
BV = Boil Volume (This is what you are taking your reading from)
FV = Final Volume (i.e. 5 gallons)
45 = # Gravity Points you get per lb of DME per gallon
So lets say you are making a 5 gallon smash beer with ...
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