I was making a pale ale the other night and I steeped some 20L Crystal grains for 30 minutes and just under 170 degrees. I had read that you can take a pre-boil hydrometer reading afterwards to gauge how well the grains worked, but when I tested mine the reading was LESS than 1.000 Did i do something wrong or do any of you know why it would read that way? The OG reading I took later on came out fine. So I think my hydrometer works properly. Thanks for any help!
Two points here: 1. At 170˚ you were stepping grains. Think of it as making a grain tea. Extracting flavor and color only, not creating sugars. I think you may be confused between steeping and mashing. What you read about preboil gravity readings are for when you mash the grain, see point #2. 2. Your reading did not detect any sugars because Crystal malt does not have the ability to self convert in the mash. Meaning you need the presence of some sort of base malt. Almost all of the enzymes needed to convert your mash (very simplistically put "making sugars available") are contained in your base malt. Someone else can probably explain it better but my suggestion is to read up on mashing. http://beersmith.com/blog/2010/01/04/diastatic-power-and-mashing-your-beer/
Crystal does not need to be mashed to add sugars, some or many of the starches have already been converted to sugars.
without getting too complicated, enzymes convert starch to sugar. enzymes are present in the grain (but not all grain!) and will work at a range of specific temperatures. some are active at say 14 to 145, others maybe 144 to 156 and so on. the enzymes all work a little differently at accomplishing the same task, that is converting starch to sugar. the vast majority of all grain brewers will hold their grain at one temp that works best for what they want. maybe 152 or 148. it is a compromise but very effective. sometimes there are multiple rests, so that each enzyme can do its work effectively. at 170F the enzymes are "denatured". so you did not extract any sugar because the enzymes were not active. Cheers. edit- aha, crystal malt! thanks John.
Taking a pre-boil gravity reading for an extract/extract & steeping grains brew isn't really necessary. The reason for taking a pre-boil gravity reading is to determine what volume to boil your wort down to based on your extraction efficiency from your mash in order to hit your target O.G. If you are not mashing, this is a redundant step because your sugars are primarily coming from your extract, so there is no efficiency to monitor. Your extract contains a certain amount of sugars and, when mixed with a certain amount of water, will result in a finite density (gravity reading). No variables, besides what total volume of water you use, will affect your gravity. In other words, just take a post-boil O.G. reading at the temperature your hydrometer is calibrated for, and you are good.
I would add that it (pre-boil gravity) is not really necessary for all-grain either (once your system is dialed in for your brewing software).
I still think it's a good practice, even if you get very consistent efficiency, because who knows? Could have a bad crush without noticing. Also, efficiency tends to vary on big beers, so if brewing one, it's still a good idea. I just like to not have surprises at the end of the brew day. If I take a pre-boil gravity reading, and it's way low, well at least I can fix it at that point. If you don't take a reading until your wort is "done" boiling and cooled down and it's way low, you're faced with the decision of a) Do I just say oh well, it's gonna be lower alcohol than intended or b) Tug on the bootstraps and get that bad boy back up to a boil and hunker down for a little while longer?
I don't take pre-boil gravitities anymore for the same reason I don't check my ph or efficiency or worry about minor volume fluctuations...they're virtually predictable. Cheers
Never did pre-boil gravity reading and I don't see why an average Home brewer need to do so. If you decided to do so, you just got yourself more information that cannot help you on your process to get your good beer.
I think knowing both pre-boil and post-boil gravities could be useful... even with extract batches, you could use them together to dial-in the boil-off rate, for example.
For all grain brewing, taking pre-boil gravity readings is very useful, especially if you don't have everything quite dialed in yet to get consistently predictable results. One time we were brewing a witbier with a target O.G. of 1.040 for an 11 gallon batch. We collected 13 gallons of wort and took a pre-boil gravity reading and got 1.026. If you know how to do some quick calculating, you know we were in trouble (and in for a long boil). We had to boil it down to 8.5 gallons to hit our target O.G. If we had just gone about our brew-day all willy-nilly without taking a pre-boil, we would have ended the brew day with 11 gallons of about 1.031 wort. Sure we could have fixed it after taking our O.G. reading, but by then we would have already added the hops and witbier adjuncts at desired increments, and bringing back to a boil would have thrown off the timing of all those additions. It was a fluke, but it can happen (and it did), which is why you should take the pre-boil gravity reading.
"Flukes" happen for a reason...the "willy-nilly" brew-day probably started long before the pre-boil gravity reading. Doesn't hurt to take one though, especially if your gut tells you something was off initially...wheat is notorius for not crushing thoroughly which is why most people double-crush it. Cheers
