Beef will get harder as it cooks because beef protein is very high, protein coagulates when it gets hot, and the longer the heating time, the more thoroughly the protein coagulates, and the harder it gets.

Also in the process of cooking, as the temperature rises, beef meat muscle fibers will begin to shrink, extrusion of water, about 60 ~ 65 degrees will be a large loss of water; if you continue to cook, the last will be more and more dry, become hard and firm, that is, we said the meat is very old. But sometimes some beef stews that are cooked over a long period of time can be quite tender.

This is because of connective tissue, another component of meat. Connective tissue is made up mainly of collagen, and if you cook it slowly over medium-low heat for a period of time, the collagen melts into gelatin, which adheres to the muscle fibers, making the meat quite juicy, and thickening the stew, giving it a tender, melt-in-your-mouth texture.

Beef food value

1, beef is rich in carnosine: beef in the carnosine content is higher than any other food, it is particularly effective in muscle growth, enhance strength. In the first few seconds of training, creatine is the source of muscle fuel, effectively replenishing adenosine triphosphate, so that training can last longer.

2, beef contains vitamin B6: the greater the protein requirement, the more vitamin B6 is added to the diet. Beef contains enough vitamin B6, can help you enhance immunity, promote protein metabolism and synthesis, thus helping the body to recover after intense training.

3. Beef contains carnitine: While chicken and fish are low in carnitine and sarcosine, beef is high. Carnitine is mainly used to support fat metabolism, producing branched-chain amino acids, an amino acid that plays an important role in muscle growth for bodybuilders.

Reference for the above: Baidu Encyclopedia-Beef