When cooking, the taste change of meat is a wonderful process, which will probably go through five stages: raw meat, raw meat, old firewood, soft rotten meat and old firewood.

"Discontinuity" means that in the initial stage of meat heating, the skin will mature rapidly, and the protein on the surface will shrink, locking the water quality and fat inside. The meat tastes tender at this time.

Like the boiled sliced meat and crispy meat that we often eat, the taste of meat is basically in this state.

Continue to heat, protein will continue to shrink. At this time, a lot of water in the meat itself will flow out, and other water in the pot has not completely penetrated into the meat. If you eat it now, you will find that the meat is very old and firewood, and you can't bite it at all.

Continue to heat, protein will continue to shrink, and the water and fat of the meat itself will continue to flow out in large quantities, but at this time, other water in the pot will also start to permeate, and the connection between fibers will start to be less firm, and the taste will start to become soft and rotten, and it will enter the stage of "the more stewed, the more brittle and rotten".

Continue to heat, protein will continue to shrink, the water and fat of the meat itself will be lost, and the water infiltration will begin to give full play to its power, making the connection between the fibers of the meat weaker and weaker, and the whole pork will begin to fibrosis.

If you eat it again at this time, you will find that it is not only tasteless, but also old, stuffed and difficult to swallow, which is why the subject thinks that "repeated heating will make wood old."