I went down a bit of a wormhole watching the posted vid...interesting stuff but looks like a hassle.
Anyway, I arrived at this particular clip where so blokes in the States do a BIAB that looks pretty straight forward and is most likley similar to what most of us do. There was a comment that critiqued the process which I thought was overly technical but also raised some interesting points. I'd been keen to hear what established BIAB people think of the following comments below this clip https://youtu.be/hVYXUbKan_8
(warning: quite a lengthy read):
Really enjoyed the demonstration. A few suggestions.
1. It is better to dough the mash in cold, 55 to 60F. Only, in the home/craft brew and grain distilling world is mash doughed in at a temperature which activates enzymes before mash pH is adjusted. Doughing in with cold water allows the brewer the opportunity to adjust mash pH before enzymes activate. This is very important, when an optimum temperature such as 152F is used, pH for the active enzyme must be optimum, as well. Otherwise enzymes will be negatively impacted. It is not a bad idea to use a pH meter.
2. When mash out is employed along with the single method, a type of starch called complex starch (amylo-pectin) enters into solution. The starch is heat resistant and it does not begin to burst until 169F. Mash out denatures enzymes and the complex starch will not be liquefied by enzymes. The starch ends up in the final product, reducing quality of the beer. Complex starch is partly responsible for body, and since, a temperature was not used which releases the starch, except during the time when enzymes were wiped out, the beer will lack body. The dextrinization rest forms A and B limit dextrin which form body. A dextrinization rest was not used. Limit dextrin is tasteless, non-fermenting sugar and it must not be confused with sweet tasting, non-fermenting sugar.
3. It isn't a good idea to squeeze out the liquid from the bagged mash. Protein mud that that grain bed catches is transferred into the wort and it ends up in the bottle, further reducing quality.
4. It is wise to use a temperature and pH which activates Beta, the rest is called the maltose rest. During the over extended rest at 152F, Beta denatured, rapidly, leaving Alpha to liquefy simple starch, amylose, at a 1-4 link. When the chain is liquefied, two chains form. The chains are called the reducing end and the non-reducing end. Alpha, continues to liquefy the reducing end until there aren't any 1-4 links left and sweet, non-fermentable sugar is left. Alpha cannot liquefy the non-reducing end because it is highly fermenting glucose. Since, Beta denatured, conversion did not take place. Beta converts glucose into maltose and malto-triose, the types of sugar which makes real beer. Enzymes convert starch into nothing. Beta converts one type of sugar into another type of sugar. When the term conversion is used in the brew house it is not attached to the word starch, the term used is mash conversion. Saccharification and conversion are not one and the same.
2. When a single temperature, single rest method is used to produce beer, it must be assumed that the malt is perfect and that the various enzymes within the malt will work harmoniously and in balance at a single temperature. Malt of that nature does not exist on the planet. To produce IPA, several temperatures are needed. To make home made beer only requires malt to be soaked in hot water. The wort produced during the demonstration was sugar imbalanced and glucose laden. It is inherent with beer produced with single method. There is no need to use a second fermentation vessel with home made beer due to high glucose level and sugar imbalanced wort. The other reason for not the need of a second fermentation vessel is due to home made beer not containing maltose and malto-triose. During second fermentation yeast absorbs maltose through the cell walls and converts it into glucose. The glucose is expelled and fermented and gravity decreases. The same thing occurs during the aging cycle with malto-triose and natural carbonation occurs. Real beer does not need to primed or artificially carbonated, home made style beer does.
The wort produced during the vid was unstable and the final product will be loaded with albuminous protein, beta glucan and it will lack body. The beer will deteriorate before adequate aging takes place. Hence, home made beer goes from the boiler to the belly in six weeks. The single method was never used as a method to produce beer. The method is used by the agencies that test malt. The temperatures which are found in every recipe for home made beer are the three temperatures used during testing procedures. Other than home brewers, the grain distilling industry uses the method, but, they aren't producing beer. However, they call the liquid moonshiner's beer. When home brewers produce moonshiner's beer and add hops to it, moonshiner's beer becomes whatever the recipe that the brewer followed, named it.