There is a wide difference between exterior and interior cuts of meat with respect to tenderness induced by cooking. When beef flank is cooked by boiling for two hours, the toughness of the fibers greatly increases during the first half hour of the cooking period, and then diminishes so that at the end of the cooking period the meat is found to be in about the same condition with respect to toughness or tenderness of the fibers as at the beginning. On the other hand, in case of the tenderloin, there is a decrease in toughness of the fibers throughout the cooking period which is particularly marked in the first few minutes of cooking, and at the end of the cooking period the meat fibers are only half as tough as before cooking. CHAPTER XII GENERAL PRINCIPLES OF COOKING Texture and Flavor of Meat--General Methods of Cooking Meat--Economies in Use of Meat. A good idea of the changes which take place while meat is being cooked can be obtained by examining a piece of flesh which has been "cooked to pieces," as the saying goes. In this the muscular fibers may be seen completely separated one from another, showing that the connective tissue has been destroyed. It is also evident that the fibers themselves are of different texture from those in the raw meat. In preparing meat for the table it is usual to stop short of the point of disintegration, but while the long process of cooking is going on the connective tissue is gradually softening and the fibers are gradually changing in texture. The former is the thing to be especially desired, but the latter is not. For this reason it is necessary to keep the temperature below the boiling point and as low as is consistent with thorough cooking, for cooks seem agreed, as the result of experience shows, that slow gentle cooking results in better texture than is the case when meat is boiled rapidly. This is the philosophy that lies back of the simmering process.