What are some scientific explanations as to why pre-hopped extract doesn't produce the best beer possible? Is there that much of a difference between a pre-hopped can hot off the line vs. one at it's expiration date? What are the chemical reactions or staling factors involved (presumed canned and O2 free)? Can these be mitigated when making the kit?
From a creative/flexibility standpoint:
Fact: PHLME has a baked in hop varietal so you can't choose that. I stock something like 60 different hops by the ounce and most of them are suitable for bittering and will give you different flavors. In other words, it's a myth that the bittering hop doesn't impact flavor at all. Yes, you can augment the brew with other hops at different timings but then you've just negated the simplicity of PHLME (which I suspect is the only reason one would buy it).
Fact: The bitterness is already locked in. Once you dilute to wort strength, it has so many IBUs and not plus or minus. Same caveat as above. You COULD jack around with the process to add more bitterness or add plain extract to dilute the hop intensity but same "why" question.
Hypothesis: The quality of hop flavor may be negatively impacted by the water removal process to make the LME. E.g. canned foods taste less fresh than fresh foods.
The other detriment is freshness, but that applies to all LME. If you're not standing in the store looking at the packaging date right on product you're about to walk out with, you have no idea what you're going to get and LME gets rank as it ages. As more people transition to all grain brewing due to the widely available all in one systems, the demand for extract slows and product sits on the shelf longer and longer. In my store maybe 10% of DME goes out destined for a beer while 90% is bought for making yeast starters. I can usually tell when it's for a recipe because it's bought with yeast and hops for example.
The only real reason to use LME is if you can't source DME at all or you don't want to learn all grain brewing (at least not yet). No matter what recipe you want to make, you can use DME and boil hops for any situation that PHLME was going to be used.
I think the best way to really see what quality differences may exist is to just brew a few different methods and taste the beer. If you want a more objective rating of where the beer lands, BJCP competitions are the best we have for that. In my previous post I was careful to suggest picking three beer styles at random because that kind of removes the ability to cherry pick styles that would do best with extracts as we've discussed in the earlier part of the thread.
) is just another ingredient for an experienced brewer to use when making great beer at home?
