GotGarlic
Chef Extraordinaire
This is not true at all, as anyone who has worked with fresh tomatoes can clearly see. I've made raw crushed tomatoes countless times and they are the same color coming out of the blender as they were going in. Cooking can change the color as caramelization of the sugars in tomatoes darkens them. Cooking also increases the amount of lycopene, which is the chemical that creates red and orange pigments in tomatoes and other fruits.Leaving in the seeds or not has no bearing on the color but the particle size of the tomato in your created sauce does.
Where in the world did you get this idea? The seeds are neutral and removing the skins does not make an appreciable difference in the acidity of tomatoes; in fact, the USDA and the National Center for Home Food Preservation recommend acidifying home-canned tomatoes whether they contain seeds and skins or not.Using skinless and seedless tomatoes to make a sauce will greatly sweeten the sauce and make it richer while leaving in the seeds and skin will increase the acids in your sauce.
Maybe this hasn't reached your area of the country yet, but heirloom tomatoes with all kinds of colors, including yellow, green, purple and pink, have become more and more popular over the past 20 years. I can buy them at Kroger nowTomatoes are extremely versatile. We use color to let people know it contains tomatoes. One reason why golden tomatoes have issues selling. (Not that they don't sell at all) Golden Tomatoes usually have a better balance between sugars and acids than red ones...but the red still outsells the golden.