Grinding and Handling Burger Meat

The key consideration when turning a cow into a hamburger is that all of those muscle proteins are designed to stick to something--generally each other to create a working muscle.  When a muscle is turned into ground meat, a lot of protein bonds are severed, and those proteins will readily bond in new and interesting ways.

The finer the grind, the more new surface area is created, and the more protein bonds are mechanically broken.  In the case of a coarse grind, there simply is less surface area for those proteins to physically get together.

Also, handling is a consideration. The more the ground meat is manipulated, the more opportunities the proteins have to stick together, because they are simply being introduced to more proteins with the ability to bond. This is a lot like kneading dough. The longer you knead the dough, the chewier it gets, because the flour is full of a protein call Gluten, and that protein forms strands as it bumps into other Gluten molecules.  Lots of molecules in a strand equals chewy bread. This is why biscuits are not chewy--one does not knead biscuit dough.

The pressure with which the burger patty is really part of the above consideration. Stronger pressure means more proteins get smashed together to form new bonds.

The time that the ground beef sits before it is cooked and served factors in.  The shorter the time, the fewer bonds that will form.

The temperature at which all of this grinding and handling also matters. Higher temperatures cause chemical reactions to occur more quickly.  Cooler temperatures have the opposite effect. For an optimal burger patty, that beef should be kept as cold as possible without freezing it. Freezing causes the beef to dry out, because ice crystal piece cell and organelle membranes.

So, if you want a tender burger....grind the beef cold, coarse, and just before you form it into a loose patty.  Then cook it immediately.

If you want a rubbery burger...grind the beef when it is warm. Grind it finely, pack it into a dense patty, and let it sit for a day or two in the refrigerator before cooking.

Here's a link to burger recipe that pretty much nails the techniques to avoid a rubbery burger.  Jump