Why does meat get tougher after cooking, but tender after cooking for a very long time (or under pressure)?

Question

Why does meat get tougher after cooking, but tender after cooking for a very long time (or under pressure)?

In: Biology

Answer 1

**Toughness:** Proteins are made up of folded amino acids. When heated, their bonds break apart and they assume a new shape. This is why an egg white goes from clear to white when heated.

**Tenderness:** Heating up the connective tissue inside the muscle causes it to liquify which is what tenderness is. If you heat for a long time at lower heat, you do a lot melting and preserve moisture. Pressure cooking adds more energy while also keeping moisture inside.