About 10 years ago, I had Saltillo tile (also known as clay tile or Mexican tile) installed on my front patio. So far it's held up well and still looks nice, however there are some fruit stains from tangerine trees that occasionally fall down and grease stains from the BBQ. What is a good product to remove these stains?

The tile was sealed upon application. Does it need to be sealed again and if so, what's a good sealant?