I press 'I' for inserting a keyframe, but couldn't find 'color keyframe' in menu. There are only 'loc','scale','rot' If I change object's color in a certain frame, then the color of object is changed too over all frames. Then how can I change color in amimation?
I did something like what Mr. Ramos did, (though I'm not as good as him). However, I thought that perhaps seeing what this creates in the Graph Editor would help you.
In the Shader Editor you can create some keyframes on a Mix Shader. Plug 2 colors into the sockets of a Mix Shader. at frame 1 put the Mix Shader factor at 0, put your mouse cursor over it and press i to create your first keyframe, the value becomes green, it means it has saved the value, it will also create a yellow dot in the Dopesheet. Then at frame 20 put the Mix Shader factor at 1, put your mouse cursor over it and press i. Now if you play the animation the color will gradually change from color 1 to color 2. If you want the color to change suddenly, at frame 19 just create a keyframe on the Mix Shader with the factor at 0, so frame 19 to frame 20 the factor will jump from 0 to 1.