Let's talk about the traditional sweet and sour sauce sweet and sour tenderloin, which is available in all major cuisines. Let me start with the sweet and sour tenderloin of Shandong cuisine and Sichuan cuisine. Only vinegar, sugar and salt are added to the traditional sweet and sour juice. Needless to say, the purpose of adding salt to sweet and sour juice is to highlight the sweet and sour flavor. There is an old saying in cooking: "If you want to add salt, add salt". Salt is the basic taste of all flavors, and its addition can set off other flavors. Traditional practice of Jinan Luokou vinegar used in sweet and sour pork tenderloin of Shandong cuisine. This vinegar is made of sweet potato and sorghum as the main raw materials. It has a fragrant smell and a soft sour taste. In addition to sweet and sour tenderloin, the famous sweet and sour carp also uses this vinegar to prepare sweet and sour juice. Baoning vinegar, the only medicinal vinegar among the four famous vinegars, is used in the sweet and sour tenderloin of Sichuan cuisine. It is made of rice and corn husk as raw materials, with Chinese herbal medicines such as Amomum villosum and Eucommia ulmoides, and refined with spring water. The sour taste is soft and the aroma is rich, and then blended with soy sauce, sugar and yellow wine in a certain proportion, and the finished product is dark yellow and reddish in color. What about tomato juice? In fact, tomato juice is an innovation made by teachers of various departments in the early years with reference to western food seasonings. To be exact, it belongs to foreign products, and the method is similar to sweet and sour juice. However, it is necessary to heat the tomato sauce (or chopped fresh tomatoes) in advance, add minced garlic and stir-fry, stir-fry the tomato sauce or chopped fresh tomatoes evenly, add sugar, vinegar and salt to dilute with water, and finally thicken. Now you can see many works of tomato juice in some innovative dishes, such as: tomato sauce tenderloin, shrimp in tomato sauce, fish fillets in tomato sauce, squirrel fish in tomato sauce and so on. So do you want tomato sauce or orange juice for the sweet and sour pork tenderloin now? Nowadays, the seasonings have changed a lot and are also rich. The traditional mode of production should be adjusted accordingly. Many times, sweet and sour juice and tomato juice are different. But in my opinion, the biggest function of using tomato sauce or orange juice in sweet and sour juice is to color. Judging from the chef's cooking habits and guests' preferences, tomato sauce or orange juice can be used on the basis of sweet and sour. The sweet and sour sauce fried with tomato sauce is bright red and has a strong tomato flavor. The sweet and sour juice made of orange juice is golden in color, which is particularly beautiful. There are also many friends who add tomato sauce and some orange juice when mixing sweet and sour juice. This is because the color of tomato sauce is too red. If the fried tenderloin is too heavy, the tenderloin made with this sweet and sour juice is too dark and has no appetite. Adding orange juice can dilute the color of tomato sauce and make the finished product more golden red. Adding tomato sauce and orange juice to sweet and sour juice can not only improve the color of dishes, but also increase the overall compound aroma. But it should be noted here that don't add too much ketchup to the sweet and sour juice, otherwise it will affect the original flavor of the sweet and sour juice.