Is anything "necessary"?
Using the BIAB method typically incorporates both a 90 minute mash and a 90 minute boil. There are graphs that show that additional sugars are indeed extracted from the grist during the thirty minutes after 60 has passed. Diminishing returns are to be determined by the brewer: is 70 minutes enough, or do I go for 90? As for a 90 minute vigorous boil (uncovered), DMS (boiling point = 37 ºC) is not an issue and will not be an issue even using Pilsen malts that are the major cause for alarm. A 90 minute vigorous boil distills off a certain amount of water in my equipment set-up. It results in a Specific Gravity (SpG) that is expertly predicted by the BIABacus. If you choose to boil less vigorously and/or for a shorter time in your equipment, you will get a different VFO and Specific Gravity at the end of your boil. Those differences can be dealt with by approaching the equation with different amounts of grist and different dilution(s) or target SpG. In the extreme case, some may not boil at all. If it works for you and your recipes, congratulations.
As for thiobarbituric acid, give me numbers!
Taste threshold? Oxidation of lipids to produce something else and its impact on taste?
Five is a sufficiently close approximation to infinity. -- Robert Firth "One, two, five." -- Monty Python and the Holy Grail
Break out the GC/MS/MS and find other components to fret about. I am not worried. I just want to make beer.
