The Brew Bag Blog — making beer

We've seen a good many videos showing how to use a fabric filter to brew in a bag, but there aren't any that detail why this works so well. Here you'll find a bit of science along with some practical information to make great beer in about 3.5 hours using minimal equipment. 

In a recent article discussing different methods of brewing, the author differentiated "all-grain" from Brew In A Bag. I had to read the sentence twice. BIAB does not use extract, does not come in a kit, (although Brewer's Best is now offering six BIAB kits that include the hops, grain, priming sugar, yeast, and caps) and utilizes the same mashing schedule as the "all grain" method. Now here's the kicker - to make beer using a brew bag you start with grain, that's right, BIAB uses nuttin but grain! I'll tell you what's happening across the USA - new and...

The utilization is influenced by the vigor of the boil, the total gravity of the boil, the time of the boil and several other minor factors. The vigor of the boil can be considered a constant for each individual brewer, but between brewers there probably is some variation. The gravity of the boil is significant because the higher the malt sugar content of a wort, the less room there is for isomerized alpha acids. The strongest bittering factors are the total amount of alpha acids you added to the wort, and the amount of time in the boil for isomerization. Understandably then, most equations for IBUs work with these three variables (gravity, amount, and time) against a nominal utilization. As mentioned earlier, the utilization for alpha acids in homebrewing is generally accepted as topping out at about 30%.

http://www.howtobrew.com/section1/chapter5-4.html

Many of the sparge brewers I talk to about BIAB scratch their heads when they hear that the brew in a bag method is a no sparge method. Nearly all of them say "but what about all the sugars that get left behind in the grain, aren't you losing valuable fermetables?" At issue is not whether no sparge "loses" fermentable sugar, but how much is actually in the boil kettle. While it is true that the grain bag after lifting from the mash tun has sugars remaining, at what point is sparging a zero return effort? The concept of brew...