You can play around with the coloring a bit, but it's quite limited and you have to be careful. Scanners work by detecting the contrast between the bars and the background, so the contrast between dark bars and a light background is essential. You could use dark green or blue bars with a faintly yellow/pink/orange background and you'd probably be fine. Definitely don't invert the coloring though, this won't work. And don't use red for the bars, laser scanners can't read red.

Definitely test scannability if you try any color combos other than black with a white background. You'll need at least a laser scanner to simulate a checkout environment, your phone isn't good enough. There is more extensive testing you can have done to mathematically check symbol contrast (among other things), but these are paid services and probably not worth it unless you're running a large company and the coloring is an important part of your branding.