Will lose nutrition while stewing soup time long

It is stewed that for a long time, people think " soup time is the longer, the soup is the more nutritious ". Then, does this kind of statement have scientific basis?

To this statement, the nutrition of medical college of Tongji University and health food research institute have carried on experiment research. They have chosen three kinds of more representative stewing dishes, namely the upper part of a leg of pork is stewed, the hen stews, the old duck stews, find through measuring : The protein of the upper part of a leg of pork and content of fat obviously increase after heating an hour, later reduced gradually.

The protein of the grass chicken and content of fat rise gradually after heating 0.5 hours, the protein heats for 1.5 hours, the fat is heated can reach the maximum in 0.75 hours; The content after heating an hour of protein of duck's meat does not change basically, the content of fat rises to supreme value while heating for 45 minutes. These three kinds stew nutrition of soup and has not increased to some extent like what people expected. Especially the hen stews and stews with the old duck, stew soup time is the longer, the lower the content of protein is, so does not need to stew the soup for a long time.

The expert reminds and says , heating for a long time can destroy the vitamin in the stewing type cooked food ; Heat for 1- 1. hours, can get three kinds of more ideal nutrition peak value of stewing the soup , the energy consumption and nutritive value at this moment are relatively good in proportion.