Kudos to the author for trying this. My approach would be to ignore the junk recipes online and see if there are any patents that describe the process. I'll have a look when I have time.
My guess would be that there's some industrial process that completely separates any yeast from anything else so as to remove any potential hop bitterness. And that there's also likely been some updates to the process over the years. It may have started out as boiling things down in the 1920s, but may have moved on to an enzyme catalyzed process these days?
On the idea of using a stout: you will end up with even more bitterness than the version you made, more than likely. Stouts (especially higher alcohol stouts) tend to be fairly generously hopped compared to a standard light lager, in order to balance the sweetness of the added malt. You just don't taste them as being super hoppy because a) the hops are added early in the boil for bittering and most of the volatile aromas boil off, and b) because, well, they're doing their job of balancing the sweet malts to make the beer not taste sickly sweet.
Author here! Thanks, though the kudos really goes to the friend who followed up on the idea of doing it and asked me to pop round in the afternoon and make some.
Re process, the linked video talks about using a centrifuge to separate the yeast and liquid, and in fact improvised a home-made centrifuge using a washing machine. It’s possible that simply skimming the top of a settled mixture is not nearly as effective and yeast contamination led to some of poor flavor notes.
As for stouts: noted, thanks, looks like I need another approach. The main reason was not just bitterness but colour: to start with a dark liquid to get a black end product. Any thoughts on how both Vegemite and Marmite end up so black?
My guess would be that there's some industrial process that completely separates any yeast from anything else so as to remove any potential hop bitterness. And that there's also likely been some updates to the process over the years. It may have started out as boiling things down in the 1920s, but may have moved on to an enzyme catalyzed process these days?
On the idea of using a stout: you will end up with even more bitterness than the version you made, more than likely. Stouts (especially higher alcohol stouts) tend to be fairly generously hopped compared to a standard light lager, in order to balance the sweetness of the added malt. You just don't taste them as being super hoppy because a) the hops are added early in the boil for bittering and most of the volatile aromas boil off, and b) because, well, they're doing their job of balancing the sweet malts to make the beer not taste sickly sweet.