It makes tons of holes in the meat to tenderize and let the marinade soak in. I’ve had amazing results by pounding the crap out of meat and marinating in the fridge overnight. I can’t even imagine how delicious it would be if I had this marinater. I might get me one.
There is at least one study showing that marinating chicken is pointless because the marinade doesn’t really penetrate the meat. I don’t know about chicken but my experiments show that vacuum marinating beef really does work. I described it in a previous Woot.
Essentially imagine your beef as a pillow. Like the pillow, there are a lot of air pockets inside the beef. Now imagine putting the pillow in one of those vacuum storage bags you see advertised on TV. When you suck out the air with a vacuum cleaner, the pillow shrinks. Opening up the bag sucks air in, rushing into the pillow as it puffs up again. That’s what’s happening when you vacuum air out of a vessel containing beef. It shrinks as the air is sucked out of its cavities. When you release the vacuum air rushes in, refilling the cavities of the meat. Now imagine that the beef was surrounded by marinade instead of air. Instead of sucking in air, it’ll suck in the marinade. Voila, instant deep marinating.
BTW, I do agree that normal marinating does very little because there is no reason for the marinade to enter the beef. In fact, osmosis would draw water out of the beef rather than draw solutes (i.e. salt and other flavorings) into the beef. That’s why they say to salt burgers after cooking, not before if you want a juicy burger. In other words, simply soaking the beef in marinade merely coats the meat. Most of the flavoring probably drips away with the fat.