There are some misconceptions in the home beer brewing culture that lead me to write this post. Efficiency is a simple term in brewer's lingo. It means the degree to which the starch in grain, with the help of enzymes, is converted to sugar(s) during the grain mash and transferred into the boil kettle. The explanation of the conversion of starches to fermentable sugars is very complicated and involves PH, water temperature, and enzymatic hydrolysis. I won't go any further on this ( because I don't know much more), but will say that all brewers key in on this term because "the number" is an indication of how effective their mash process is - which means big money for breweries and small money for home brewer's. In either case it, the number leads to many conversations about equipment and technique, grain and water ratios, temperature, sparging technique, and any other portion of the lautering process.
The following chart was taken from how to brew by John Palmer - www.howtobrew.com
It simply shows the temperature ranges of the water needed to induce enzymatic conversion during the mash. This mash results in the formation of sugar (s) - some fermentable and some not - which is then converted by yeast to alcohol during fermentation.
The first step in producing the highest possible efficiency number is to understand that the grain needs to be crushed. This rids the grain of the husk, breaks the kernel into pieces and exposes the grain (endosperm) to water. Grain mill settings are often a topic of discussion as home brewers seek the holy grail of high 80"s efficiency. Three vessel brewers use a more coarse crush (and get less enzymatic action) because too fine of a crush has the potential to clog their filtering system. Brew in a bag brewers take advantage of a fine crush (and get more enzymatic action) because the filtering system (the bag) never clogs.
The key to understanding efficiency is to first understand the potential of the grain itself. Again, this is somewhat complicated so I'll simply say that malts are kilned (toasted) to stop the germination process. Germination is what creates the enzymes and gives grain it's diastatic (conversion) potential. The darker the malt has been toasted, the lower its potential; because the enzymes have been denatured (killed) by heat. The lighter the malt the higher it's conversion potential. That's why "base grain" (light colored, lightly toasted) is the majority of a grain bill with flavor and color grains making up a small percentage of the bill. Without the base grain the wort would have little fermentable sugar.
The Brew Bag allows a finer crush which exposes more of the endosperm to water, thus enabling more enzymatic hydrolysis (conversion) to occur - faster. 3V brewers use a coarser crush (some even add rice hulls to create a less compact filter bed) and spend 45 to 90 minutes rinsing the grain to achieve negligible results. So if the results are similar why would anyone spend more time doing it? I think they like the process, they like being in the arena with breweries. Professional brewers spend a lot of time cleaning and unloading mash tuns - lots of time, and I think 3V home brewers identify with these folks - and that's good. But if a pro-brewer could cut time off his day, which means money in his pocket, wouldn't it be logical to do it?
Just this morning on Facebook, a 3-vessel brewer confidently stated that his 90-minute fly sparge allowed him to taste more beers. Wow - what a long brew day! He heats strike water for 30 minutes, mashes for 60 minutes, sparges for 90 minutes, boils for at least 60 minutes, and depending on his set up - cools for 20 to 40 minutes and then cleans 3 vessels. And unless they use The Brew Bag for coolers - they get to scoop the spent grain out of their mash tun.