"Is the effect of freezing meat so large that it can be detected by blind testing?"
Yes, in the case of pemmican made from previously frozen beef, it's very obvious. The basic flavor notes don't change much but they become more intense. Both in the protein and the fat, the flavor will become stronger. The texture (mouth feel) also changes - night and day. I think both of these effects are mainly due to the difference in texture.
Pemmican is made of dried meat powder mixed with melted, rendered fat, 50/50 by weight, then allowed to solidify. That's the ancient formula given by Viljhalmur Steffansson, the Arctic explorer who wrote the book on pemmican.
Pemmican made from never frozen, dried and powdered meat has a sandy texture - small grains. Because the muscle cells are not damaged by freezing, they are too strong for the blender blades to shatter them completely. Below a certain size, the meat particles lack the inertia to react against the spinning blades by breaking, and just bounce off. With a 50/50 mix of meat and fat, the pemmican can be formed into stiff cakes. The fat melts in the mouth, leaving a sandy textured mass of fat covered meat particles. The flavor of the meat is overshadowed by the fat.
My pemmican made from previously frozen then dried and powdered meat is much different. The blender blades shatter the meat particles into a fine fluffy powder that looks a little bit like loose fiberglass insulation or chopped up cotton candy. If I mix this 50/50 by weight with fat, it is much too dry. This powder has much greater surface area and because the cell walls are all broken, much more capacity for absorption. Soaks up a lot more fat, so if the pemmican is made with 50/50 protein/fat by weight, it comes out dry, but the beef flavor is more intense due to the greater ratio of surface area to mass of each meat particle.
If I want to avoid a loose texture, I have to add more fat than 50/50, more like 40/60 meat/fat or 45/65. That gives me enough liquid to form the pemmican into blocks that hold together. Because the fibers still have a much greater ratio of surface area to mass, more of their surface is exposed to the taste buds, so the flavor of the meat is more intense, and because the fat amount is greater in any mouthful, there is more of a fat flavor.