This video on a homemade grout cleaning solution is a quick tutorial on how to make whats called an oxygen bleach. It's actually the same components you find in Oxi Clean and similar oxygen bleaches. Baking soda and hydrogen peroxide are the components used to make the DIY oxygen bleach for grout cleaning. It is safer then normal liquid bleach because there is less chance for toxic off gassing of chlorine gases. If you've ever mixed bleach and ammonia you get chloramine vapors which are a respiratory irritant. So don't mix them together.
I've used oxygen bleaches to clean hard surfaces in my own home and they are a good way to take care of a some stubborn stains. Some things to note about cleaning your grout with a oxygen bleach. They take a lot longer to work then liquid chlorine bleach and they kill mold, but can kill mildew.
Although I do like this grout cleaning solution I would not trust it to kill mold and other bacteria in my home.