Originally Posted by BoJack Horseman
And this is while refrigerated?
(generally speaking) all meat is 'aged' before it is sold, but how meat producers go about it and how long it takes varies depending on the type of meat and how much they want to spend doing it.
to "dry age" beef, it will generally be hung as a whole carcass (or a side) and refrigerated in a very specific environment, very low humidity, and a constant temp of between 1-3 degrees in a well ventilated area and has to be monitored to ensure it doesn't spoil.
this can be anything up to 30 days, but will need a minimum of 11 days and usually 20-25 days is the optimum length of time for a good bit of meat as the chances of the meat spoiling increases with each day it is hung.
a couple of different things happen during this time. the water in the meat starts to evaporate, which on it's own will concentrate the flavours and will (as a side effect) shrink the meat, and make it more tasty than if you'd just eaten it on day one.
also, and in just these perfect conditions the normal chemical processes in the meat that happen when the cow is still alive can continue, so the cells still absorb oxygen from the blood, which produces lactic acid which (as it's not being used for anything else since the cow is dead) in turn breaks down the cell walls and connective tissues of the meat, making it much more tender and flavourful as well as changing the colour from light red to a much darker colour.
the downsides to dry aging beef is that it shrinks quite a lot (up to 15%), so you lose volume), and some of the outside may need to be cut away depending on how long it was aged for and how successful the process was.
obviously, as this is a slow process, the meat has to be stored in a specific environment and monitored constantly, so it's not cheap.
by comparison, wet aging takes only 4-10 days, so it's a lot cheaper and only needs basic refrigeration which can be done in transit to wherever the meat is being sold. the short version is that it gets shrink wrapped and hermetically sealed in plastic right after it's slaughtered.
it is "wet aged" as (due to being sealed in) none of the moisture escapes, so that 10-15% loss in volume you get with dry aging meat doesn't happen, plus the enzyme breakdown still has enough time to happen (just about) so by the time it gets to your plate, it will have an *acceptable* flavour compared to non-dry aged meat.
you can pretty much guarantee that unless your meat is labelled as dry aged, it will have been wet aged. anyone who loves a good steak will generally go for a dry aged cut if possible.